naphthoquinones and 1-4-naphthoquinone

1,4-naphthoquinones are the most widespread naphthoquinone compounds. Recently, many 1,4-naphthoquinone glycosides with different structural features have been obtained from both nature and synthesis, which has led to an increasing variety of naphthoquinone glycosides. In this paper, the structure variety and biological activity in recent 20 years are reviewed, and classified them according to the source and structure characteristics. Meanwhile the synthetic methods of O-, S-, C- and N-naphthoquinone glycosides and their structure activity relationships are also described. It was referred that the presence of polar groups of C2 and C5 and non-polar groups attached to C3 on the naphthoquinone ring are beneficial for their biological activities. It will provide more comprehensive literature resources for the future research of 1, 4-naphthoquinone glycosides and lay a theoretical foundation.

Topics: Glycosides; Naphthoquinones; Structure-Activity Relationship

Over the past decade, a number of new 1,4-naphthoquinones have been isolated from natural sources and new 1,4-naphthoquinones with diverse structural features have been synthesized. Cardioprotective, anti-ischemic, hepatoprotective, neuroprotective and some other new properties were found for these compounds; their role in protecting against neurodegenerative diseases has been established. Their anti-inflammatory, antimicrobial and antitumor activities have been studied in more detail; new, previously unknown intracellular molecular targets and mechanisms of action have been discovered. Some compounds of this class are already being used as a medicinal drugs and some substances can be used as biochemical tools and probes for non-invasive detection of pathological areas in cells and tissues in myocardial infarction and neurodegenerative diseases using modern molecular imaging techniques.

Topics: Anti-Infective Agents; Anti-Inflammatory Agents; Bacteria; Cytokines; Humans; Leukocytes, Mononuclear; Naphthoquinones; Oxidative Stress; Protective Agents; Trypanosoma

1,4-Naphthoquinone (1,4-NQ; CAS RN 130-15-4), a derivative of naphthalene, is a commonly used pre-cursor in industrial processes. Since the early 1980's 1,4-NQ has been tested in a number of genotoxicity assays, both in vitro and in vivo. There is strong evidence that 1,4-NQ does not induce gene mutations in bacteria or mammalian cells in vitro with predominantly negative Ames tests and negative Hprt and tk mutation studies. However, there is clear evidence of a clastogenic response in vitro from positive micronucleus, sister chromatid exchange and chromosome aberration assays. 1,4-NQ-treated mice and hamsters were, however, negative for micronucleus or chromosomal aberration induction in GLP-compliant studies with clear evidence of target tissue exposure, suggesting an in vitro only effect. Evidence indicates that the mechanism of in vitro clastogenicity is predominantly via ROS generation, and since in vitro mammalian cell tests systems have poor anti-oxidant defence mechanisms, they are particularly sensitive to oxidative DNA damage. On the other hand, healthy mammalian tissues have more efficient anti-oxidant defence mechanisms, and therefore it is not surprising that 1,4-NQ is not genotoxic in vivo.

Topics: Animals; Chromosome Aberrations; DNA Damage; Humans; Mutagens; Naphthoquinones

Naphthoquinones may cause oxidative stress in exposed cells and, therefore, affect redox signaling. Here, contributions of redox cycling and alkylating properties of quinones (both natural and synthetic, such as plumbagin, juglone, lawsone, menadione, methoxy-naphthoquinones, and others) to cellular and inter-cellular signaling processes are discussed: (i) naphthoquinone-induced Nrf2-dependent modulation of gene expression and its potentially beneficial outcome; (ii) the modulation of receptor tyrosine kinases, such as the epidermal growth factor receptor by naphthoquinones, resulting in altered gap junctional intercellular communication. Generation of reactive oxygen species and modulation of redox signaling are properties of naphthoquinones that render them interesting leads for the development of novel compounds of potential use in various therapeutic settings.

Topics: Alkylating Agents; Animals; Cell Communication; Humans; Naphthoquinones; Oxidation-Reduction; Oxidative Stress; Protein Processing, Post-Translational; Receptor Protein-Tyrosine Kinases; Signal Transduction

Targeting the redox metabolism of Plasmodium falciparum to create a fatal overload of oxidative stress is a route to explore the discovery of new antimalarial drugs. There are three main possibilities to target the redox metabolism of P. falciparum at the erythrocytic stage: selective targeting and inhibition of a redox P. falciparum protein or enzyme; oxidant drugs targeting essential parasite components and heme by-products; and redox cycler drugs targeting the parasitized red blood cell. Oxidants and redox cycler agents, with or without specific targets, may disrupt the fragile parasitized erythrocyte redox-dependent architecture given that: redox equilibrium plays a vital role at the erythrocytic stage; P. falciparum possesses major NADPH-dependent redox systems, such as glutathione and thioredoxin ones; and the protein-NADPH-dependent phosphorylation-dephosphorylation process is involved in building new permeation pathways and channels for the nutrient-waste import-export traffic of the parasite.

Topics: Antimalarials; Erythrocytes; Humans; Naphthoquinones; Oxidative Stress; Oxidoreductases; Plasmodium falciparum; Protozoan Proteins

The homodimeric flavoenzyme glutathione reductase catalyzes NADPH-dependent glutathione disulfide reduction. This reaction is important for keeping the redox homeostasis in human cells and in the human pathogen Plasmodium falciparum. Different types of NADPH-dependent disulfide reductase inhibitors were designed in various chemical series to evaluate the impact of each inhibition mode on the propagation of the parasites. Against malaria parasites in cultures the most potent and specific effects were observed for redox-active agents acting as subversive substrates for both glutathione reductases of the Plasmodium-infected red blood cells. In their oxidized form, these redox-active compounds are reduced by NADPH-dependent flavoenzyme-catalyzed reactions in the cytosol of infected erythrocytes. In their reduced forms, these compounds can reduce molecular oxygen to reactive oxygen species, or reduce oxidants like methemoglobin, the major nutrient of the parasite, to indigestible hemoglobin. Furthermore, studies on a fluorinated suicide-substrate of the human glutathione reductase indicate that the glutathione reductase-catalyzed bioactivation of 3-benzylnaphthoquinones to the corresponding reduced 3-benzoyl metabolites is essential for the observed antimalarial activity. In conclusion, the antimalarial lead naphthoquinones are suggested to perturb the major redox equilibria of the targeted cells. These effects result in developmental arrest of the parasite and contribute to the removal of the parasitized erythrocytes by macrophages.

Topics: Antimalarials; Catalysis; Drug Design; Glutathione Reductase; Humans; Malaria, Falciparum; Molecular Structure; NADP; Naphthoquinones; Oxidation-Reduction; Plasmodium falciparum

Vitamin Ks (VKs) are fat-soluble quinone compounds known to have various bioactivities. This review describes the inflammatory effects of VKs and their related quinone derivatives based on DNA polymerase (pol) inhibition. VK3, but not VK1 or VK2 (=MK-4), inhibited the activity of human pol γ, which is the DNA replicative pol in mitochondria. Of the intermediate compounds between VK2 and VK3 (namely MK-3, MK-2 and MK-1), MK-2 was the strongest inhibitor of mammalian pols α, κ and λ, which belong to the B-, Y- and X-families of pols, respectively. Among the VK3 based quinone derivatives, such as 1,4-naphthoquinone (NQ), 2-dimethyl-1,4-naphthoquinone (1,2-dimethyl-NQ), 1,4-benzoquinone (BQ), 9,10-anthraquinone (AQ) and 5,12-naphthacenequinone (NCQ), NQ was the strongest inhibitor of mammalian pols α and λ, in particular, DNA repair-related pol λ. Among the all compounds tested, NQ displayed the strongest suppression of tumor necrosis factor (TNF)-α production induced by lipopolysaccharide (LPS) in a cell culture system using RAW264.7 mouse macrophages. NQ also suppressed the expression of pol λ protein in these cells, after LPS-treated RAW264.7 cells were stimulated to induce pol λ expression. In an in vivo mouse model of LPS-evoked acute inflammation, intraperitoneal injection of NQ into mice suppressed TNF-α production in peritoneal macrophages and serum. In an in vivo colitis mouse model induced using dextran sulfate sodium (DSS), NQ markedly suppressed DSS-evoked colitis. The promising anti-inflammatory candidates based on the inhibition of DNA repair-related pols, such as pol λ, by VKs quinone derivatives, such as NQ, are discussed.

Topics: Animals; DNA Polymerase beta; DNA Polymerase gamma; DNA Polymerase I; DNA Repair; DNA-Directed DNA Polymerase; Humans; Inflammation; Mice; Mitochondria; Naphthoquinones; Nucleic Acid Synthesis Inhibitors; Tumor Necrosis Factor-alpha; Vitamin K

The genus Diospyros is one of the most important sources of bioactive compounds, exclusively 1,4-naphthoquinones. The following information is an attempt to cover the developments in the biology and phytochemistry of 1,4-naphthoquinones isolated from this genus, as well as the studies done and the suggested mechanisms regarding their activities. During the past 60 years, many of these agents have been isolated from Diospyros L. Twelve considerable bioactive structures are reported in this review. The basic 1,4-naphthoquinone skeletons, on which a large number of studies have been done, are plumbagin and diospyrin. Today, the potential for development of leads from 1,4-naphthoquinones obtained from Diospyros L. is growing dramatically, mainly in the area of anticancer and antibacterial investigations. The data prepared and described here are intended to be served as a reference tool to the natural products and chemistry specialists in order to expand the rational drug design.

Topics: Anti-Bacterial Agents; Antineoplastic Agents, Phytogenic; Diospyros; Naphthoquinones

Quinone moieties are present in many drugs such as anthracyclines, daunorubicin, doxorubicin, mitomycin, mitoxantrones and saintopin, which are used clinically in the therapy of solid cancers. The cytotoxic effects of these quinones are mainly due to the following two factors: (i) inhibition of DNA topoisomerase-II and, (ii) formation of semiquinone radical that can transfer an electron to oxygen to produce super oxide, which is catalyzed by flavoenzymes such as NADPH-cytochrome-P-450 reductase. Both semiquinone and super oxide of quinones can generate the hydroxyl radical, which is the cause of DNA strand breaks. 1,4-naphthoquinone contains two quinone groups that have the ability to accept one or two electrons to form the corresponding radical anion or di-anion species. It is probably dependent on the quinone redox cycling that yields "reactive oxygen species" (ROS) as well as arylation reactions, which is common to quinones for biological relevance. In the present review, an attempt has been made to collect the cytotoxicity data on different series of 1,4-naphthoquinones against four different cancer cell lines that are L1210, A549, SNU-1, and K562, which were acquired by using identical method, and has been discussed in terms of QSAR (quantitative structure-activity relationships) to understand the chemical-biological interactions. QSAR results have shown that the cytotoxic activities of 1,4-naphthoquinones depend largely on their hydrophobicity.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Doxorubicin; Humans; Hydrophobic and Hydrophilic Interactions; K562 Cells; Leukemia L1210; Mitoxantrone; Naphthoquinones; Quantitative Structure-Activity Relationship

Black carbon (BC) is an important component of atmospheric PM 2.5 and the second largest contributor to global warming. 1,4-naphthoquinone-coated BC (1,4 NQ-BC) is a secondary particle with great research value, so we chose 1,4 NQ-BC as the research object. In our study, mitochondria and lysosomes were selected as targets to confirm whether they were impaired by 1,4 NQ-BC, label free proteomics technology, fluorescent probes, qRT-PCR and western blots were used to investigate the mechanism of 1,4 NQ-BC toxicity. We found 494 differentially expressed proteins (DEPs) in mitochondria and 86 DEPs in lysosomes using a proteomics analysis of THP1 cells after 1,4 NQ-BC exposure for 24 h. Through proteomics analysis and related experiments, we found that 1,4 NQ-BC can damage THP-1-M cells by obstructing autophagy, increasing lysosomal membrane permeability, disturbing the balance of ROS, and reducing the mitochondrial membrane potential. It is worth noting that 1,4 NQ-BC prevented the removal of FTL by inhibiting autophagy, and increased IL-33 level by POR/FTL/IL-33 axis. We first applied proteomics to study the damage mechanism of 1,4 NQ-BC on THP1 cells. Our research will enrich knowledge of the mechanism by which 1,4 NQ-BC damages human macrophages and identify important therapeutic targets and adverse outcome pathways for 1,4 NQ-BC-induced damage.

Topics: Apoferritins; Autophagy; Humans; Interleukin-33; Lysosomes; Macrophages; Naphthoquinones; Soot; Up-Regulation

P2X7 receptors (P2X7Rs) are ligand-gated ion channels that play a significant role in inflammation and are considered a potential therapeutic target for some inflammatory diseases. We have previously shown that a number of synthetic 1,4-naphthoquinones are capable of blocking P2X7Rs in neuronal and macrophage cells. In the present investigation, we have demonstrated the ability of the tetracyclic quinone-thioglucoside conjugate

Topics: Adenosine Triphosphate; Anti-Inflammatory Agents; Humans; Inflammation; Macrophages; Naphthoquinones; Receptors, Purinergic P2X7; Thioglucosides

1,4-naphthoquinone and its derivatives have attracted widespread attention due to their multiple biological activities, such as induction of cancer cell apoptosis; however, most of these compounds have high cytotoxicity. In this study, in order to reduce their toxicity and increase their potential anti-tumor effects, we synthesized a novel 1,4-naphthoquinone derivative named 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone (NTDMNQ), and investigated its apoptotic effects and underlying mechanism. Our results showed that NTDMNQ inhibited the viability of HepG2, Hep3B, and Huh7 human hepatocellular carcinoma (HCC) cells. It also increased the accumulation of cells in the G0/G1 phase of the cell cycle by increasing the expression levels of p-p53, p21 and p27, while decreasing the levels of Cyclin D1, Cyclin E, Cyclin-dependent kinase 2 (CDK2), CDK4, and CDK6. Inhibition of reactive oxygen species (ROS) by the ROS scavenger N-acetyl-L-cysteine (NAC) decreased apoptosis in NTDMNQ-treated cells. Western blot analysis showed that NTDMNQ increased the phosphorylation of p38 and c-Jun N-terminal kinase (JNK), and decreased the phosphorylation of extracellular signal-regulated kinase (ERK), AKT, and signal transducer and activator of transcription-3 (STAT3); these effects were blocked by NAC. Both the JNK inhibitor (SP600125) and p38 inhibitor (SB203580) reversed the phosphorylation of STAT3, and the ERK inhibitor (FR180204) and AKT inhibitor (LY294002) reduced the expression of STAT3. Taken together, these findings suggest that NTDMNQ induces apoptosis via ROS-mediated MAPK, AKT and STAT3 signaling pathways in HepG2 cells, and may be a potent anticancer agent.

Topics: Apoptosis; Carcinoma, Hepatocellular; Hep G2 Cells; Humans; Liver Neoplasms; Naphthalenes; Naphthoquinones; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor

The studies on nitronaphthoquinone derivatives are rare in the literature, and the nitro group associated with the aromatic ring in the quinone system is known to increase the biological activity of naphthoquinone due to its electron-withdrawing properties. In the course of quinone derivatives, the new N(H)-substituted-5-nitro-1,4-naphthoquinones (NQ) as regioisomers were synthesized by reactions of 2,3-dichloro-5-nitro-1,4-naphthoquinone with some heterocyclic ring substituted nucleophiles such as anilines, piperazines, or morpholines, according to a Michael 1,4-addition mechanism. Five NQ regioisomer couples having different functional group (2-chloro-isomers 3, 5, 7, 9 and 13; 3-chloro-isomers 2, 4, 6, 8 and 12) are reported here. All new synthesized compounds were characterized by spectroscopic methods and two-dimensional NMR techniques 1H-1H correlated spectroscopy (COSY).The synthesized NQ regioisomers were evaluated for catalase enzyme inhibitory activities and antioxidant efficiency. The synthesized regioisomers were screened for their antioxidant capacity using the cupric-reducing antioxidant capacity (CUPRAC) method. 2-Chloro-3-((2,4-dimethoxyphenyl)amino)-5-nitronaphthalene-1,4-dione (5) showed the highest antioxidant capacity with a 1.80±0.06 CUPRAC-trolox equivalent antioxidant capacity (TEAC) coefficient. Compound 5 also showed strongest catalase enzyme inhibitory activity. The antioxidant capacity results of all 2-chloro regioisomers are higher than the 3-chloro regioisomers. Likewise, also catalase enzyme inhibitory activities results were determined in the same way, except for one regioisomer pair. The catalase was effectively inhibited by the newly synthesized compounds, with % inhibition values in the range of 0.71-0.86%. Some of these NQ compounds also showed remarkable antioxidant capacities.

Topics: Antioxidants; Catalase; Naphthoquinones

As air pollution has been paid more attention to by public in recent years, effects and mechanism in particulate matter-triggered health problems become a focus of research. Lysosomes and mitochondria play an important role in regulation of inflammation. Interleukin-33 (IL-33) has been proved to promote inflammation in our previous studies. In this research, macrophage cell line RAW264.7 was used to explore the potential mechanism of upregulation of IL-33 induced by 1,4-naphthoquinone black carbon (1,4-NQ-BC), and to explore changes of lysosomes and mitochondria during the process.. 50 μg/mL 1,4-NQ-BC exposure for 24 h dramatically increased expression of IL-33 in RAW264.7 cells. Lysosomal membrane permeability was damaged by 1,4-NQ-BC treatment, and higher mitochondrial membrane potential and ROS level were induced by 1,4-NQ-BC. The results of proteomics suggested that expression of ferritin light chain was increased after cells were challenged with 1,4-NQ-BC, and it was verified by Western blot. Meanwhile, expressions of p62 and LC3B-II were increased by 50 μg/mL 1,4-NQ-BC in RAW264.7 cells. Ultimately, expression of IL-33 could return to same level as control in cells treated with 50 μg/mL 1,4-NQ-BC and 50 μM deferoxamine combined.. 1,4-NQ-BC induces IL-33 upregulation in RAW264.7 cells, and it is responsible for higher lysosomal membrane permeability and ROS level, lower mitochondrial membrane potential, and inhibition of autophagy. Ferritin light chain possibly plays an important role in the upregulation of IL-33 evoked by 1,4-NQ-BC.

Topics: Animals; Apoferritins; Carbon; Humans; Inflammation; Interleukin-33; Mice; Naphthoquinones; RAW 264.7 Cells; Reactive Oxygen Species; Soot; Up-Regulation

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; DNA Damage; Drug Resistance, Neoplasm; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid; Leukocytes, Mononuclear; Naphthoquinones; Up-Regulation

Non-covalent interactions between aromatic molecules and water are fundamental in many chemical and biological processes, and their accurate description is essential to understand molecular relative configurations. Here we present the rotational spectroscopy study of the water complexes of the polycyclic aromatic hydrocarbon 1,4-naphthoquinone (1,4-NQ). In 1,4-NQ-(H

Topics: Hydrogen Bonding; Molecular Conformation; Naphthoquinones; Water

Targeted screening using the MTT cell viability test with a mini-library of natural and synthetic 1,4-naphthoquinones and their derivatives was performed in order to increase the survival of Neuro-2a neuroblastoma cells in in vitro paraquat and 6-hydroxydopamine models of Parkinson's disease. As a result, 10 compounds were selected that could protect neuronal cells from the cytotoxic effects of both paraquat and 6-hydroxydopamine. The five most active compounds at low concentrations were found to significantly protect the activity of nonspecific esterase from the inhibitory effects of neurotoxins, defend cell biomembranes from lytic destruction in the presence of paraquat and 6-hydroxydopamine, and normalize the cell cycle. The protective effects of these compounds are associated with the suppression of oxidative stress, decreased expression of reactive oxygen species and nitric oxide formation in cells and normalization of mitochondrial function, and restoration of the mitochondrial membrane potential altered by neurotoxins. It was suggested that the neuroprotective activity of the studied 1,4-NQs is attributable to their pronounced antioxidant and free radical scavenging activity and their ability to reduce the amount of reactive oxygen species formed by paraquat and 6-hydroxydopamine action on neuronal cells. The significant correlation between the neuroprotective properties of 1,4-naphthoquinones and Quantitative Structure-Activity Relationship descriptors describing the physicochemical properties of these compounds means that the hydrophobicity, polarity, charge, and shape of the molecules can be of decisive importance in determining the biological activity of studied substances.

Topics: Animals; Biphenyl Compounds; Cell Cycle; Cell Line; Cell Survival; Free Radical Scavengers; Membrane Potential, Mitochondrial; Mice; Models, Biological; Naphthoquinones; Neuroprotection; Neuroprotective Agents; Neurotoxins; Nitric Oxide; Oxidopamine; Paraquat; Picrates; Quantitative Structure-Activity Relationship; Reactive Oxygen Species; Reproducibility of Results

Topics: Anti-Bacterial Agents; beta-Lactams; Drug Resistance, Multiple, Bacterial; Drug Synergism; Humans; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Naphthoquinones; Staphylococcal Infections

Staphylococcus aureus, a Gram-positive opportunistic microorganism, promotes pathogenicity in the human host through biofilm formation. Microorganisms associated with biofilm often exhibit drug-resistance property that poses a major threat to public healthcare. Thus, the exploration of new therapeutic approaches is the need of the hour to manage biofilm-borne infections. In the present study, efforts are put together to test the antimicrobial as well as antibiofilm activity of 1,4-naphthoquinone against Staphylococcus aureus. The result showed that the minimum bactericidal concentration (MBC) of this compound was found to be 100 µg/mL against Staphylococcus aureus. In this regard, an array of experiments (crystal violet, biofilm protein measurement, and microscopic analysis) related to biofilm assay were conducted with the sub-MBC concentrations (1/20 and 1/10 MBC) of 1,4-naphthoquinone. All the results of biofilm assay demonstrated that these tested concentrations (1/20 and 1/10 MBC) of the compound (1,4-naphthoquinone) showed a significant reduction in biofilm development by Staphylococcus aureus. Moreover, the tested concentrations (1/20 and 1/10 MBC) of the compound (1,4-naphthoquinone) were able to reduce the microbial motility of Staphylococcus aureus that might affect the development of biofilm. Further studies revealed that the treatment of 1,4-naphthoquinone to the organism was found to increase the cellular accumulation of reactive oxygen species (ROS) that resulted in the inhibition of biofilm formation by Staphylococcus aureus. Hence, it can be concluded that 1,4-naphthoquinone might be considered as a promising compound towards biofilm inhibition caused by Staphylococcus aureus.

Topics: Anti-Bacterial Agents; Biofilms; Humans; Microbial Sensitivity Tests; Naphthoquinones; Reactive Oxygen Species; Staphylococcal Infections; Staphylococcus aureus

A series of 1,4-naphthoquinone derivatives of lawsone (1), 6-hydroxy-1,4-naphthoquinone (2), and juglone (3) were synthesized by alkylation, acylation, and sulfonylation reactions. The yields of lawsone derivatives 1a-1k (type A), 6-hydroxy-1,4-naphthoquinone derivatives 2a-2j (type B), and juglone derivatives 3a-3h (type C) were 52-99%, 53-96%, and 28-95%, respectively. All compounds were tested in vitro for the cytotoxicity against human oral epidermoid carcinoma (KB) and cervix epithelioid carcinoma (HeLa) cells and their structure-activity relationship was studied. Compound 3c was found to be most potent in KB cell line (IC

Topics: Antineoplastic Agents; Cell Proliferation; DNA Topoisomerases, Type I; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; HeLa Cells; Humans; KB Cells; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Structure-Activity Relationship; Topoisomerase I Inhibitors

Staphylococcus aureus causes several nosocomial and community-acquired infections in human host involving biofilm. Thus, strategies need to be explored to curb biofilm threats by either inhibiting the formation of biofilm or disintegrating the pre-existing biofilm. Towards this direction, we had already revealed the biofilm inhibiting properties of 1,4-naphthoquinone against S. aureus. In this study, we have investigated whether this compound can act on pre-existing biofilm. Hence, biofilm of S. aureus was developed first and challenged further with 1,4-naphthoquinone. Experiments such as crystal violet assay, fluorescence microscopy, and estimation of total biofilm protein were performed to confirm the biofilm disintegration properties of 1,4-naphthoquinone. The disintegration of pre-existing biofilm could be attributed to the generation of reactive oxygen species (ROS). To investigate further, we observed that extracellular DNA (eDNA) was found to play an important role in holding the biofilm network as DNaseI treatment could cause an efficient disintegration of the same. To examine the effect of ROS on the eDNA, we exposed pre-existing biofilm to either 1,4-naphthoquinone or a combination of both 1,4-naphthoquinone and ascorbic acid for different length of time. Post-incubation, ROS generation and the amount of eDNA associated with the biofilm were determined wherein an inversely proportional relationship was observed between them. The result indicated that with the increase of ROS generation, the amount of eDNA associated with biofilm got decreased substantially. Thus, the results indicated that the generation of ROS could degrade the eDNA thereby compromising the integrity of biofilm which lead to the disintegration of pre-existing biofilm.

Topics: Biofilms; Humans; Naphthoquinones; Reactive Oxygen Species; Staphylococcal Infections; Staphylococcus aureus

A hallmark of cancer cells is their ability to reprogram nutrient metabolism. Thus, disruption to this phenotype is a potential avenue for anti-cancer therapy. Herein we used a phenotypic chemical library screening approach to identify molecules that disrupted nutrient metabolism (by increasing cellular oxygen consumption rate) and were toxic to cancer cells. From this screen we discovered a 1,4-Naphthoquinone (referred to as BH10) that is toxic to a broad range of cancer cell types. BH10 has improved cancer-selective toxicity compared to doxorubicin, 17-AAG, vitamin K3, and other known anti-cancer quinones. BH10 increases glucose oxidation via both mitochondrial and pentose phosphate pathways, decreases glycolysis, lowers GSH:GSSG and NAPDH/NAPD

Topics: Benzoquinones; Cell Line, Tumor; Cell Survival; Doxorubicin; Glycolysis; Humans; Lactams, Macrocyclic; Mitochondria; Naphthoquinones; Oxidative Stress; Oxygen Consumption; Phenotype; Small Molecule Libraries; Vitamin K 3

This study investigated the bioactivities of polyhydroxyl-1,4-naphthoquinone (PHNQ) extracts from Evechinus chloroticus shell waste. PHNQs were extracted from E. chloroticus shells and spines using different solvents and the crude extracts were fractionated by HPLC. The antioxidant activity of the PHNQ extracts were evaluated by the DPPH, ABTS, ORAC and FRAP assays. Ethyl acetate was the best extraction solvent and spine extracts showed better antioxidant activity than shell extracts (p < 0.05). The HPLC fraction containing spinochrome E showed the highest antioxidant activity (p < 0.05). The Minimum Inhibitory Concentration of the PHNQ crude extracts and the HPLC fractions ranged from 250 to 2500 µg/mL depending on the PHNQ extract and microbial species tested. Treatment by PHNQ extracts resulted in alteration of the morphology of the microbial cell wall as observed by transmission electron microscopy. PHNQ extracts also exhibited anti-inflammatory activity in rats (ED

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents; Antioxidants; Male; Microbial Sensitivity Tests; Naphthoquinones; Rats; Rats, Sprague-Dawley; Sea Urchins

An increase in the production of reactive oxygen species (ROS) in mitochondria due to targeted delivery of redox active compounds may be useful in studies of modulation of cell functions by mitochondrial ROS. Recently, the mitochondria-targeted derivative of menadione (MitoK

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Humans; Hydrogen Peroxide; Mitochondria; Naphthoquinones; Oxidative Phosphorylation; Oxygen; Phosphorus Compounds; Reactive Oxygen Species

The phenomenon of high sugar consumption by tumor cells is known as Warburg effect. It results from a high glycolysis rate, used by tumors as preferred metabolic pathway even in aerobic conditions. Targeting the Warburg effect to specifically deliver sugar conjugated cytotoxic compounds into tumor cells is a promising approach to create new selective drugs. We designed, synthesized, and analyzed a library of novel 6-S-(1,4-naphthoquinone-2-yl)-d-glucose chimera molecules (SABs)-novel sugar conjugates of 1,4-naphthoquinone analogs of the sea urchin pigments spinochromes, which have previously shown anticancer properties. A sulfur linker (thioether bond) was used to prevent potential hydrolysis by human glycoside-unspecific enzymes. The synthesized compounds exhibited a Warburg effect mediated selectivity to human prostate cancer cells (including highly drug-resistant cell lines). Mitochondria were identified as a primary cellular target of SABs. The mechanism of action included mitochondria membrane permeabilization, followed by ROS upregulation and release of cytotoxic mitochondrial proteins (AIF and cytochrome C) to the cytoplasm, which led to the consequent caspase-9 and -3 activation, PARP cleavage, and apoptosis-like cell death. These results enable us to further clinically develop these compounds for effective Warburg effect targeting.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Drug Screening Assays, Antitumor; Glucose; Humans; Male; Membrane Potential, Mitochondrial; Mitochondrial Membranes; Naphthoquinones; Pigments, Biological; Prostatic Neoplasms; Sea Urchins; Warburg Effect, Oncologic

1,2-naphthoquinone (1,2-NQ) and 1,4-naphthoquinone (1,4-NQ) are clinically promising biologically active chemicals that have been shown to stimulate the aryl hydrocarbon receptor (AhR) signaling pathway, but whether they are direct or indirect ligands or activate the AhR in a ligand-independent manner is unknown. Given the structural diversity of AhR ligands, multiple mechanisms of AhR activation of gene expression, and species differences in AhR ligand binding and response, we examined the ability of 1,2-NQ and 1,4-NQ to bind to and activate the mouse and human AhRs using a series of in vitro AhR-specific bioassays and in silico modeling techniques. Both NQs induced AhR-dependent gene expression in mouse and human hepatoma cells, but were more potent and efficacious in human cells. 1,2-NQ and 1,4-NQ stimulated AhR transformation and DNA binding in vitro and was inhibited by AhR antagonists. Ligand binding analysis confirmed the ability of 1,2-NQ and 1,4-NQ to competitively bind to the AhR ligand binding cavity and the molecular determinants for interactions were predicted by molecular modeling methods. NQs were shown to bind distinctly differently from that of 2,3,7,8-tetrachlorodibenzo-

Topics: Animals; Aryl Hydrocarbon Receptor Nuclear Translocator; Basic Helix-Loop-Helix Transcription Factors; Binding Sites; Binding, Competitive; Cell Line; Chlorocebus aethiops; COS Cells; Cytochrome P-450 CYP1A1; DNA; Gene Expression Regulation; Humans; Mice; Models, Molecular; Molecular Docking Simulation; Mutation; Naphthoquinones; Polychlorinated Dibenzodioxins; Receptors, Aryl Hydrocarbon; Species Specificity

Topics: Antineoplastic Agents; cdc25 Phosphatases; Cell Line, Tumor; Cell Survival; Enzyme Inhibitors; Humans; MAP Kinase Kinase 7; Models, Molecular; Molecular Docking Simulation; Naphthoquinones

Although ascomycetes occupy a vaster niche in soil than the well-studied basidiomycetes, they have received limited attention in studies related to bioremediation. In this study, the degradation of carbaryl by Xylaria sp. was studied in different culture conditions and its possible metabolic pathway was elucidated. In liquid culture, 99% of the added carbaryl was eliminated when cytochrome P450 (CYP450) was active, which was similar to the degradation rate of Pleurotus ostreatus, a fungus with strong bioremediation ability. Mn

Topics: Benzoic Acid; Biodegradation, Environmental; Carbaryl; Cytochrome P-450 Enzyme System; Laccase; Manganese; Metabolic Networks and Pathways; Naphthols; Naphthoquinones; Pleurotus; Soil Microbiology; Xylariales

Extracellular adenosine 5'-triphosphate (ATP) triggers the P2X7 receptor (P2X7R) ionic channel to stimulate the release of the interleukin-IL-1β cytokine into macrophages. The current study explored the reaction of six structurally diverse triazole derivatives on P2X7-mediated dye uptake into murine peritoneal macrophages. P2X7R activity determined by ATP-evoked fluorescent dye uptake. Triazole derivatives toxicity measured using dextran rhodamine exclusion based colorimetric assay. A740004 and BBG, both P2X7R antagonist, inhibited ATP-induced dye uptake. In contrast, the derivatives 5a, 5b, 5e, and 5f did not diminish P2X7R activity in concentrations until 100 µM. 5c and 5d analogs caused a potent inhibitory activity on P2X7-induced dye uptake. Dextran Rhodamine exclusion measurements after 24 h of continuous treatment with triazole derivatives indicated a moderated toxicity for all molecules. In conclusion, this study showed that a series of new hybrid 1,2,3-triazolic naphthoquinones reduces P2X7R-induced dye uptake into murine macrophages. In silico analysis indicates a good pharmacokinetic profile and molecular docking results of these analogs indicate the potential to bind into an allosteric site located into the P2X7R pore and juxtaposed with the ATP binding pocket. In this manner, the compounds 5c and 5d may be used as a scaffold for new P2X7R inhibitors with reduced toxicity, and good anti-inflammatory activity.

Topics: Allosteric Site; Animals; Binding Sites; Caco-2 Cells; Cell Line; Coloring Agents; Humans; Macrophages; Mice; Microsomes, Liver; Molecular Docking Simulation; Naphthoquinones; Permeability; Protein Structure, Tertiary; Purinergic P2X Receptor Antagonists; Receptors, Purinergic P2X7; Triazoles

Derivatives of 1,4‑naphthoquinone have excellent anti‑cancer effects, but their use has been greatly limited due to their serious side effects. To develop compounds with decreased side effects and improved anti‑cancer activity, two novel types of 1,4‑naphthoquinone derivatives, 2,3‑dihydro‑2,3‑epoxy‑2‑propylsulfonyl‑5,8‑dimethoxy‑1,4‑naphthoquinone (EPDMNQ) and 2,3‑dihydro‑2,3‑epoxy‑2‑nonylsulfonyl‑5,8‑dimethoxy‑1,4‑naphthoquinone (ENDMNQ) were synthesized and their anti‑tumor activities were investigated. The effects of EPDMNQ and ENDMNQ on cell viability, apoptosis and accumulation of reactive oxygen species (ROS) in liver cancer cells were determined by MTT cell viability assay and flow cytometry. The expression levels of mitochondrial, mitogen activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling pathway‑associated proteins in Hep3B liver cancer cells were analyzed by western blot analysis. The results demonstrated that EPDMNQ and ENDMNQ inhibited the proliferation of liver cancer Hep3B, HepG2, and Huh7 cell lines but not that of normal liver L‑02, normal lung IMR‑90 and stomach GES‑1 cell lines. The number of apoptotic cells and ROS levels were significantly increased following treatment with EPDMNQ and ENDMNQ, and these effects were blocked by the ROS inhibitor N‑acetyl‑L‑cysteine (NAC) in Hep3B cells. EPDMNQ and ENDMNQ induced apoptosis by upregulating the protein expression of p38 MAPK and c‑Jun N‑terminal kinase and downregulating extracellular signal‑regulated kinase and STAT3; these effects were inhibited by NAC. The results of the present study demonstrated that EPDMNQ and ENDMNQ induced apoptosis through ROS‑modulated MAPK and STAT3 signaling pathways in Hep3B cells. Therefore, these novel 1,4‑naphthoquinone derivatives may be useful as anticancer agents for the treatment of liver cancer.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; MAP Kinase Signaling System; Mitochondria; Naphthoquinones; p38 Mitogen-Activated Protein Kinases; Reactive Oxygen Species; STAT3 Transcription Factor

1,4-Naphthoquinones are exceptional building blocks in organic synthesis and have been used to synthesize several well-known pharmaceutically active agents. Herein we report the synthesis, structural characterization, and biological evaluation of new phenylaminosulfanyl-1,4-naphthoquinone derivatives. We evaluated the cytotoxic activity of the synthesized compounds against three human cancer cell lines: A549, HeLa, and MCF-7. Most of the synthesized compounds displayed potent cytotoxic activity. Specifically, compounds 5 e [3,5-dichloro-N-(4-((4-((1,4-dioxo-3-(phenylthio)-1,4-dihydronaphthalen-2-yl)amino)phenyl)sulfonyl)phenyl)benzamide], 5 f [N-(4-((4-((1,4-dioxo-3-(phenylthio)-1,4-dihydronaphthalen-2-yl)amino)phenyl)sulfonyl)phenyl)-3,5-dinitrobenzamide], and 5 p [N-(4-((4-((1,4-dioxo-3-(phenylthio)-1,4-dihydronaphthalen-2-yl)amino)phenyl)sulfonyl)phenyl)thiophene-2-carboxamide] showed remarkable cytotoxic activity. The synthesized compounds showed low toxicity in normal human kidney HEK293 cells. The cytotoxic mechanism of compounds 5 e, 5 f, and 5 p was explored in MCF-7 cells. The results confirmed that these three compounds induce apoptosis and arrest the cell cycle at the G

Topics: Antineoplastic Agents; Apoptosis; Caspase 3; Caspase 7; Cell Cycle; Cell Line; Cell Survival; Drug Screening Assays, Antitumor; Gene Expression Regulation; Humans; Molecular Structure; Naphthoquinones; Structure-Activity Relationship

Hit, Lead & Candidate Discovery Antiangiogenesis therapy is a promising way for treatment of solid cancers, and many angiogenesis inhibitors that target vascular endothelial growth factor (VEGF) or its receptors have been developed. We explored novel antiangiogenic compounds other than anti-VEGF drugs by screening our synthetic compound library and found that 6-thiophen-3-yl-2-methoxy-1,4-naphthoquinone (6-TMNQ) had potential as a novel angiogenesis inhibitor. This paper describes the effects of 6-TMNQ on angiogenesis and tumor growth in vitro and in vivo. 6-TMNQ inhibited serum-, VEGF-, and basic fibroblast growth factor (bFGF)-stimulated proliferation of endothelial cells in a concentration-dependent manner, but had no effect on the proliferation of fibroblasts. VEGF-induced activation of VEGF receptor-2 in endothelial cells was not affected by the compound. 6-TMNQ markedly abrogated both migration and tube formation of endothelial cells. Orally administered 6-TMNQ inhibited angiogenesis in response to VEGF or bFGF in mice in a dose-dependent manner. Furthermore, when tumor-bearing mice were treated with 6-TMNQ, increase in tumor size was significantly prevented due to inhibition of angiogenesis in the tumor tissues. These results demonstrate that 6-TMNQ is an orally available compound that selectively inhibits endothelial cell proliferation and migration, and abrogates angiogenesis, resulting in the prevention of tumor growth. The mechanism of 6-TMNQ action is different from that of conventional anti-VEGF drugs.

Topics: Administration, Oral; Animals; Antineoplastic Agents; Cell Line; Cell Movement; Cell Proliferation; Cell Survival; Endothelial Cells; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Naphthoquinones; Neoplasms; Neovascularization, Pathologic; Vascular Endothelial Growth Factor Receptor-2

Multi-drug resistance (MDR) to anticancer drugs is the primary impediment to successful treatment of cancer. Hunting for new compounds with potent anti-MDR activity is an effectual approach to conquer cancer drug resistance. In this work, 33 new sulfur-containing 1,4-naphthoquinone oxime derivatives were prepared and investigated for their cytotoxicity against a panel of tumor cell lines and fibroblast normal cell line. Cell-based assay showed that most of target compounds displayed more potent cytotoxic potency than positive controls. Meanwhile, all of compounds were non-toxic to normal cells. More importantly, the cytotoxic activity of these oxime derivatives toward drug-resistant cancer cell lines was found to be much stronger than that toward drug-susceptible cell lines (anti-drug resistance coefficient (ADRC) > 1). Of these, compound 12 m was identified as the most effective molecule with IC50 values in the range of 0.29 ± 0.01 to 1.33 ± 0.05 μM toward MDR sublines. Further mechanism studies demonstrated that 12 m could inhibit colony formation, cause G1 phase arrest and promote cell apoptosis mediated by augmenting Bax/Bcl-2 ratio of Bel7402/5-FU cells. Our findings provide promising start points for development of sulfur-containing 1,4-naphthoquinone oxime derivatives as potential anti-MDR agents.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Naphthoquinones; Oximes; Structure-Activity Relationship; Sulfur

The natural compound 1,4-naphthoquinone has potent anti-tumor activity. However, the clinical application of 1,4-naphthoquinone and its derivatives has been limited by their side effects. In this study, we attempted to reduce the toxicity of 1,4-naphthoquinone by synthesizing two derivatives: 2,3-dihydro-2,3-epoxy-2-propylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (EPDMNQ) and 2,3-dihydro-2,3-epoxy-2-nonylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (ENDMNQ). Then we evaluated the cytotoxicity and molecular mechanisms of these compounds in lung cancer cells. EPDMNQ and ENDMNQ significantly inhibited the viabilities of three lung cancer cell lines and induced A549 cell cycle arrest at the G1 phase. In addition, they induced the apoptosis of A549 lung cancer cells by increasing the phosphorylation of p38 and c-Jun N-terminal kinase (p-JNK), and decreasing the phosphorylation of extracellular signal-related kinase (p-ERK), protein kinase B (Akt), and signal transducer and activator of transcription 3 (STAT3). Furthermore, they increased reactive oxygen species (ROS) levels in A549 cells; however, pretreatment with the ROS inhibitor N-acetyl-l-cysteine significantly inhibited EPDMNQ- and ENDMNQ-mediated apoptosis and reversed apoptotic proteins expression. In conclusion, EPDMNQ and ENDMNQ induced G1 phase cell cycle arrest and apoptosis in A549 cells via the ROS-mediated activation of mitogen activated protein kinase (MAPK), Akt and STAT3 signaling pathways.

Topics: Acetylcysteine; Apoptosis; Cell Line, Tumor; Drug Design; G1 Phase Cell Cycle Checkpoints; Humans; Lung Neoplasms; Mitogen-Activated Protein Kinases; Naphthoquinones; Phosphorylation; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor

Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (

Topics: Cotyledon; Indoleacetic Acids; Naphthoquinones; Oxidative Stress; Plant Growth Regulators; Zea mays

Recent clinical approvals of brain imaging radiotracers targeting amyloid-β provided clinicians the tools to detect and confirm Alzheimer's disease pathology without autopsy or biopsy. While current imaging agents are effective in postsymptomatic Alzheimer's patients, there is much room for improvement in earlier diagnosis, hence prompting a need for new and improved amyloid imaging agents. Here we synthesized 41 novel 1,4-naphthoquinone derivatives and initially discovered 14 antiamyloidogenic compounds via in vitro amyloid-β aggregation assay; however, qualitative analyses of these compounds produced conflicting results and required further investigation. Follow-up docking and biophysical studies revealed that four of these compounds penetrate the blood-brain barrier, directly bind to amyloid-β aggregates, and enhance fluorescence properties upon interaction. These compounds specifically stain both diffuse and dense-core amyloid-β plaques in brain sections of APP/PS1 double transgenic Alzheimer's mouse models. Our findings suggest 1,4-naphthoquinones as a new scaffold for amyloid-β imaging agents for early stage Alzheimer's.

Topics: Amyloid beta-Protein Precursor; Animals; Brain; Fluorescent Dyes; Mice; Mice, Transgenic; Naphthoquinones; Plaque, Amyloid; Presenilin-1

The 1,4-naphthoquinones and their derivatives have garnered great interest due to their antitumor pharmacological properties in various cancers; however, their clinical application is limited by side effects. In this study, to reduce side effects and improve therapeutic efficacy, a novel 1,4-naphthoquinone derivative-2-(4-methoxyphenylthio)-5,8-dimethoxy-1,4-naphthoquinone (MPTDMNQ) was synthesized. We investigated the effects and underlying mechanisms of MPTDMNQ on cell viability, apoptosis, and reactive oxygen species (ROS) generation in human gastric cancer cells. Our results showed that MPTDMNQ decreased cell viability in nine human gastric cancer cell lines. MPTDMNQ significantly induced apoptosis accompanied by the accumulation of ROS in GC cells. However, pre-treatment with the ROS scavenger N-acetyl-L-cysteine (NAC) attenuated the MPTDMNQ-induced apoptosis. Moreover, MPTDMNQ decreased the phosphorylation levels of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3); and increased the phosphorylation levels of c-Jun N-terminal kinase (JNK) and p38 kinase. However, phosphorylation was inhibited by NAC and a mitogen-activated protein kinase (MAPK) inhibitor. These findings showed that MPTDMNQ induced AGS cell apoptosis via ROS-mediated MAPK and STAT3 signaling pathways. Thus, MPTDMNQ may be a promising candidate for treating gastric cancer.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Humans; Mitogen-Activated Protein Kinases; Naphthoquinones; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor; Stomach Neoplasms

A series of novel, substituted 2-chloro-3-[(thiazol-2-yl)amino]-1,4-naphthoquinones have been prepared and shown to exhibit promising concentration-dependent activity against human SH-SY5Y cells, Plasmodium falciparum, Mycobacterium tuberculosis and P. aeruginosa. Substituent effects on observed bioactivity have been explored; the para-fluorophenyl derivative 3d exhibited activity across the range of the bioassays employed, indicating the potential of the 2-chloro-3-[(4-arylthiazol-2-yl)amino]-1,4-naphthoquinone scaffold in the development of novel, broad spectrum therapeutics.

Topics: Humans; Molecular Structure; Naphthoquinones; Structure-Activity Relationship

Transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) plays a key role in detoxification of electrophiles via formation of glutathione (GSH) adducts and subsequent excretion into extracellular spaces. We found that reactive sulfur species (RSS), such as cysteine persulfides produced by cystathionine [Formula: see text] (CSE), capture environmental electrophiles through formation of sulfur adducts. However, contributions of Nrf2 and CSE to the blockage of environmental electrophile-mediated toxicity remain to be evaluated.. The aim of this study was to clarify roles that CSE and Nrf2 play in the protection against various environmental electrophiles. We also wished to clarify the molecular basis of the developmental window of toxicity through investigating expression levels of Nrf2, RSS-producing enzymes, and sulfur nucleophiles during developmental stages of mice.. Wild-type (WT), CSE knockout (KO), Nrf2 KO, Nrf2/CSE double KO (DKO) mice, and their primary hepatocytes were analyzed in this study. Cadmium (Cd), methylmercury (MeHg), 1,4-naphthoquinone, crotonaldehyde, and acrylamide were used. We conducted Western blotting, real-time polymerase chain reaction (PCR), 3-(4,5-dimethylthiazol-2-yl)-2,5-triphenyl tetrazolium bromide (MTT) assays, liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis, alanine transaminase (ALT) activity, histopathological analysis, and rotarod test.. Primary hepatocytes from DKO mice were significantly more sensitive to the environmental electrophiles than each single KO counterpart. Both Nrf2 and CSE single KO mice were highly susceptible to Cd and MeHg, and such sensitivity was further exacerbated in the DKO mice. Lower-level expressions of CSE and sulfur nucleophiles than those in adult mice were observed in a window of developmental stage.. Our mouse model provided new insights into the response to environmental electrophiles; while Nrf2 is recognized as a key transcription factor for detoxification of environmental electrophiles, CSE is crucial factor to repress their toxicity in a parallel mode. In addition, the sensitivity of fetuses to MeHg appears to be, at least in part, associated with the restricted production of RSS due to low-level expression of CSE. https://doi.org/10.1289/EHP4949.

Topics: Acrylamide; Aldehydes; Animals; Cadmium; Cystathionine gamma-Lyase; Female; Gene Expression Regulation, Enzymologic; Hepatocytes; Male; Methylmercury Compounds; Mice; Mice, Knockout; Naphthoquinones; NF-E2-Related Factor 2; Sulfides

1,4-naphthoquinones, especially juglone, are known for their anticancer activity. However, plumbagin, lawsone, and menadione have been less investigated for these properties. Therefore, we aimed to determine the effects of plumbagin, lawsone, and menadione on C6 glioblastoma cell viability, ROS production, and mitochondrial function.. Cell viability was assessed spectrophotometrically using metabolic activity method, and by fluorescent Hoechst/propidium iodide nuclear staining. ROS generation was measured fluorometrically using DCFH-DA. Oxygen uptake rates were recorded by the high-resolution respirometer Oxygraph-2k.. Plumbagin and menadione displayed highly cytotoxic activity on C6 cells (IC. Plumbagin and menadione exhibit strong prooxidant, mitochondrial oxidative phosphorylation uncoupling and cytotoxic activity. In contrast, lawsone demonstrates a moderate effect on C6 cell viability and mitochondrial functions, and possesses strong antioxidant properties.

Topics: Animals; Antineoplastic Agents; Antioxidants; Apoptosis; Cell Line, Tumor; Cell Survival; Glioblastoma; Mitochondria; Naphthoquinones; Oxidants; Oxidation-Reduction; Oxidative Stress; Phosphorylation; Phytotherapy; Plant Extracts; Rats; Reactive Oxygen Species; Uncoupling Agents; Vitamin K 3

AKT, also known as protein kinase B (PKB), is an established therapeutic target in cancer and its inhibitors are increasingly designed. The anti-cancer potential of a compound class naphthoquinones has been constantly realized. The current work aimed to explore AKT1 inhibitors from 1,4-naphthoquionone derivatives.. A library of 1,4-naphthoquionone derivatives was formed using similarity search and visual analysis. The library was used for virtual screening using molecular docking. For the screened compounds, the detailed binding pose analysis, binding energy and dissociation constant calculations were performed.. The top 10 screened compounds were proposed as potential AKT1 inhibitors with anti-cancer activity. The compounds were checked for any reported activity, and our 2nd rank compound was reported to have anti-cancer activity.. Our study proposes 10 compounds as potential AKT1 inhibitors and anticancer agents and also provides insights into their binding. This study also proposes AKT1 as a potential target of the reported anticancer compound, CID: 341807.

Topics: Antineoplastic Agents; Cell Line, Tumor; Humans; Naphthoquinones; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction

1,4‑Naphthoquinone derivatives have superior anticancer effects, but their use has been severely limited in clinical practice due to adverse side effects. To reduce the side effects and extend the anticancer effects of 1,4‑naphthoquinone derivatives, 2‑(butane‑1‑sulfinyl)‑1,4‑naphthoquinone (BQ) and 2‑(octane‑1‑sulfinyl)‑1,4‑naphthoquinone (OQ) were synthesized, and their anticancer activities were investigated. The anti‑proliferation effects, determined by MTT assays, showed that BQ and OQ significantly inhibited the viability of gastric cancer cells and had no significant cytotoxic effect on normal cell lines. The apoptotic effect was determined by flow cytometry, and the results showed that BQ and OQ induced cell apoptosis by regulating the mitochondrial pathway and cell cycle arrest at the G2/M phase via inhibition of the Akt signaling pathway in AGS cells. Furthermore, BQ and OQ significantly increased the levels of reactive oxygen species (ROS) and this effect was blocked by the ROS scavenger NAC in AGS cells. BQ and OQ induced apoptosis by upregulating the protein expression of p38 and JNK and downregulating the levels of ERK and STAT3. Furthermore, expression levels of these proteins were also blocked after NAC treatment. These results demonstrated that BQ and OQ induced apoptosis and cell cycle arrest at the G2/M phase in AGS cells by stimulating ROS generation, which caused subsequent activation of MAPK, Akt and STAT3 signaling pathways. Thus, BQ and OQ may serve as potential therapeutic agents for the treatment of human gastric cancer.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Humans; MAP Kinase Signaling System; Naphthoquinones; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor; Stomach Neoplasms

P2X7 receptor (P2X7R) is an ATP-gated ion-channel with potential therapeutic applications. In this study, we prepared and searched a series of 1,4-naphthoquinones derivatives to evaluate their antagonistic effect on both human and murine P2X7 receptors. We explored the structure-activity relationship and binding mode of the most active compounds using a molecular modeling approach. Biological analysis of this series (eight analogues and two compounds) revealed significant in vitro inhibition against both human and murine P2X7R. Further characterization revealed that AN-03 and AN-04 had greater potency than BBG and A740003 in inhibiting dye uptake, IL-1β release, and carrageenan-induced paw edema in vivo. Moreover, we used electrophysiology and molecular docking analysis for characterizing AN-03 and AN-04 action mechanism. These results suggest 1,4-napthoquinones, mainly AN-04, as potential leads to design new P2X7R blockers and anti-inflammatory drugs.

Topics: Animals; Drug Design; HEK293 Cells; Humans; Mice; Molecular Docking Simulation; Naphthoquinones; Protein Conformation; Purinergic P2X Receptor Antagonists; Receptors, Purinergic P2X7; Structure-Activity Relationship

Leishmaniasis has become a significant public health issue in several countries in the world. New products have been identified to treat against the disease; however, toxicity and/or high cost is a limitation. The present work evaluated the antileishmanial activity of a new naphthoquinone derivate, Flau-A [2-(2,3,4-tri-O-acetyl-6-deoxy-β-L-galactopyranosyloxy)-1,4-naphthoquinone], against promastigote and amastigote-like stages of Leishmania amazonensis and L. infantum. In addition, the cytotoxicity in murine macrophages and human red cells was also investigated. The mechanism of action of Flau-A was assessed in L. amazonensis as well as its efficacy in treating infected macrophages and inhibiting infection of pretreated parasites. Results showed that Flau-A was effective against promastigotes and amastigote-like forms of both parasite species, as well as showed low toxicity in mammalian cells. Results also highlighted the morphological and biochemical alterations induced by Flau-A in L. amazonensis, including loss of mitochondrial membrane potential, as well as increased reactive oxygen species production, cell shrinkage, and alteration of the plasma membrane integrity. The present study demonstrates for the first time the antileishmanial activity of Flau-A against two Leishmania species and suggests that the mitochondria of the parasites may be the main target organelle. Data shown here encourages the use of this molecule in new studies concerning treatment against Leishmania infection in mammalian hosts.

Topics: Animals; Antiprotozoal Agents; Erythrocytes; Female; Humans; Leishmania infantum; Leishmania mexicana; Macrophages; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Mitochondria; Naphthoquinones

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; K562 Cells; Molecular Structure; Naphthoquinones; Reactive Oxygen Species; Structure-Activity Relationship

1,4-Naphthoquinone and its derivatives have shown some efficacy as therapeutic compounds for cancer and inflammation, though their clinical application is limited by their side-effects. To reduce the toxicity of these compounds and optimize their effects, we synthesized two 1,4-naphthoquinone derivatives-2-butylsulfinyl- 1,4-naphthoquinone (BSNQ) and 2-octylsulfinyl-1,4-naphthoquinone (OSNQ)-and investigated their effects and underlying mechanisms in hepatocellular carcinoma cells. BSNQ and OSNQ decreased cell viability and significantly induced apoptosis, accompanied by the accumulation of reactive oxygen species (ROS). However, pretreatment with N-acetyl-l-cysteine, a specific ROS scavenger, blocked apoptosis. Western blot results indicated that BSNQ and OSNQ up-regulated the phosphorylation of p38 and JNK, and down-regulated the phosphorylation of ERK, Akt and STAT3, and that these effects were blocked by N-acetyl-l-cysteine. Furthermore, BSNQ and OSNQ suppressed tumor growth and modulated MAPK and STAT3 signaling in mouse xenografts without detectable effects on body weight or hematological parameters. These results indicate that BSNQ and OSNQ induce apoptosis in human hepatoma Hep3B cells via ROS-mediated p38/MAPK, Akt and STAT3 signaling pathways, suggesting that these 1,4-naphthoquinone derivatives may provide promising new anticancer agents to treat HCC.

Topics: Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Humans; Liver Neoplasms; MAP Kinase Signaling System; Naphthoquinones; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; STAT3 Transcription Factor

Chemotherapy and targeted therapies have made important strides in cancer treatment yet they often fail and new therapies are still needed. Here, we employed a phenotypic screen to identify and analyze the mechanism of action of novel small molecules that interfere with critical pathways involved in tumor cell growth, using chemoresistant A375 melanoma cells as a model.. Cell culture studies were performed in ATCC-recommended media. Compounds, and compound libraries were obtained from Boston University or purchased commercially. Effects on A375 cell viability, proliferation and morphology were determined by Celigo Image Cytometer and viability staining. Anticancer activity of the lead compound was tested in a xenograft nude mouse model. Signaling and cell death pathways were analyzed by SDS-PAGE and immunoblotting, and/or fluorescence microscopy.. After evaluating 4477 compounds, one hit compound CB533 was identified that caused significant reduction of A375 cell growth. CB533 is an unexplored 1,4-naphthoquinone (NQ) derivative which unlike 1,4-NQ, induced rapid cell death without generating reactive oxygen species (ROS). Structure-activity relationship analysis showed that a pyrrolidine in the 1,4-NQ nucleus in lead compound Pyr-1 yielded optimal activity. CB533 and Pyr-1 had growth-suppressing effects on a large variety of chemotherapy-resistant cancer cell lines in the nano to picomolar range. Pyr-1 also significantly reduced growth of MDA-MB-231 breast cancer cells in nude mice. Pyr-1 rapidly induced activation of major stress pathways and autophagy, which was efficiently blocked by ERK, and somewhat by PI3K inhibitors.. CB533 and lead Pyr-1 represent novel broad-spectrum, anticancer compounds that are up to 1000-fold more potent than plumbagin, a natural 1,4-NQ with known anticancer activity. Since the growth suppression activities of CB533 and Pyr-1 are unaffected by the chemotherapy resistance of cancer cells, these compounds have promising therapeutic potential. The pyrrolidine in the 3 position of the 1,4-NQ nucleus of Pyr-1 is a critical component of the pharmacophore. Pyr-1-induced cellular stress was mediated by an ERK, and to a lesser extent by an AKT-dependent pathway without involving apoptosis. Our data suggest that Pyr-1 derives its greatly enhanced antitumor activity via mimicking ROS-induced stress signaling without generating ROS, and likely committing cells to autophagy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Female; Humans; Mice; Mice, Nude; Naphthoquinones; Signal Transduction; Structure-Activity Relationship

In this study, we applied various assays to find new activities of 1,4-naphthoquinone derivatives for potential anti-Candida albicans applications.. These assays determined (a) the antimicrobial effect on growth/cell multiplication in fungal cultures, (b) the effect on formation of hyphae and biofilm, (c) the influence on cell membrane integrity, (d) the effect on cell morphology using atomic force microscopy, and (e) toxicity against zebrafish embryos. We have demonstrated the activity of these compounds against different Candida species and clinical isolates of C. albicans.. 1,4-Naphthoquinones significantly affected fungal strains at 8-250 mg l. Our research has evidenced the effectiveness of 1,4-naphthoquinones as potential anti-Candida agents.

Topics: Animals; Antifungal Agents; Candida albicans; Candidiasis; Drug Evaluation, Preclinical; Humans; Hyphae; Microbial Sensitivity Tests; Naphthoquinones; Zebrafish

Naphthoquinone amino derivatives exhibit interesting physicochemical properties and a wide range of biological activities with potential medicinal applications. A clean, fast and simple method for the preparation of phenylamino-1,4-naphthoquinones is presented by the reaction of naphthoquinone (NQ) and anilines under ultrasound irradiation (US). Anilino derivatives were synthesized in good yields and shorter reaction times in comparison with the conventional method. This ultrasound procedure can be applied to the preparation of naphthoquinone derivatives with anilines containing electron-donor substituents (2-OMe, 4-OMe, 4-Me and 4-OEt) or halogen or electron-withdrawing substituents (4-F, 4-Cl, 4-Br, 3-F, 3-Cl, 3-Br, 4-Ac). This procedure was also applied to the reaction of anilines with 2,3-dichloro-1,4-naphthoquinone (DCNQ). A reaction mechanism involving an EDA complex is proposed based on NMR experiments and previous studies about solid/solid reactions.

Topics: Aniline Compounds; Naphthoquinones; Ultrasonic Waves

Glioblastoma multiform (GBM) is the most common and devastating type of primary brain tumor, being considered the deadliest of human cancers. In this context, extensive efforts have been undertaken to develop new drugs that exhibit both antiproliferation and antimetastasis effects on GBM. 1,4-Naphthoquinone (1,4-NQ) scaffold has been found in compounds able to inhibit important biological targets associated with cancer, which includes DNA topoisomerase, Hsp90 and monoamine oxidase. Among potential antineoplastic 1,4-NQs is the plant-derived lapachol (2-hydroxy-3-prenyl-1,4-naphthoquinone) that was found to be active against the Walker-256 carcinoma and Yoshida sarcoma. In the present study, we examined the effect of polyamine (PA)-conjugated derivatives of lapachol, nor-lapachol and lawsone on the growth and invasion of the human GBM cells. The conjugation with PA (a spermidine analog) resulted in dose-dependent and time-dependent increase of cytotoxicity of the 1,4-NQs. In addition, in-vitro inhibition of GBM cell invasion by lapachol was increased upon PA conjugation. Previous biochemical experiments indicated that these PA-1,4-NQs are capable of inhibiting DNA human topoisomerase II-α (topo2α), a major enzyme involved in maintaining DNA topology. Herein, we applied molecular docking to investigate the binding of PA-1,4-NQs to the ATPase site of topo2α. The most active molecules preferentially bind at the ATP-binding site of topo2α, which is energetically favored by the conjugation with PA. Taken together, these findings suggested that the PA-1,4-NQ conjugates might represent potential molecules in the development of new drugs in chemotherapy for malignant brain tumors.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Astrocytes; Binding Sites; Brain Neoplasms; Cell Line, Tumor; Cerebral Cortex; DNA Topoisomerases, Type II; Glioblastoma; Humans; Mice; Naphthoquinones; Polyamines; Primary Cell Culture

To establish the structure-activity relationship of 5-hydroxy-1,4-naphthoquinones toward anticancer activity, a series of its derivatives were prepared and tested for the activity (IC

Topics: Antineoplastic Agents; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Naphthoquinones; Structure-Activity Relationship; Tumor Cells, Cultured

In an effort to develop potent and selective antitumor agents, a series of 1,4-naphthoquinone oxime derivatives were designed and synthesized. The cytotoxicity of these compounds were evaluated against five human cancer cell lines (colorectal cancer cell: HCT-15, breast cancer cell: MDA-MB-231, liver cancer cell: BEL-7402, colorectal cancer cell: HCT-116 and ovarian cancer cell: A2780) in vitro. Among them, compound 14 was found to be the most potent cytotoxic compound against three cell lines (MDA-MB-231, BEL-7402 and A2780) with IC

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Naphthoquinones; Oximes; Structure-Activity Relationship

Naphthoquinone derivatives have various pharmacological properties. Here, we describe the synthesis of new 1,4-naphthoquinone derivatives inspired by lawsone and β-lapachone and their effects on both migration of fibroblasts in vitro and dermal wound healing in diabetic mice. NMR and FTIR spectroscopy aided characterization of chemical composition and demonstrated the molecular variations after the synthesis of four different derivatives, namely 2-bromo-1,4-naphthoquinone (termed derivative S3), 2-N-phenylamino-1,4-naphthoquinone (derivative S5), 2-N-isonicotinoyl-hydrazide-1,4-naphthoquinone (derivative S6), and 1-N-isonicotinoyl-hydrazone-[2-hydroxy-3-(3-methyl-2-butenyl)]-1,4-naphthoquinone (derivative S7). Our results indicate that derivatives S3, S5, S6 and S7 were non-toxic to the 3T3 fibroblast cell line. In scratch assays, derivatives S3 and S6, but not S5 or S7, stimulated the migration of fibroblasts. Compared with untreated diabetic mice, S3, S6 and S7 treatments accelerated wound closure. However, derivative S3 was optimal for the stimulation of epithelization, thereby increasing the number of keratinocyte layers and blood vessels, and reducing diffuse cellular infiltration, compared to derivatives S6 and S7. Our results suggest that novel 1,4-naphthoquinone derivatives promote fibroblast migration and accelerate wound closure under diabetic conditions.

Topics: 3T3 Cells; Administration, Topical; Alloxan; Animals; Carbon-13 Magnetic Resonance Spectroscopy; Cell Movement; Cell Survival; Diabetes Mellitus, Experimental; Fibroblasts; Male; Mice; Naphthoquinones; Proton Magnetic Resonance Spectroscopy; Spectroscopy, Fourier Transform Infrared; Wound Healing

Novel 1,4-naphthoquinones possessing indole scaffolds were prepared by the reaction of 2-hydroxy-1,4-naphthoquinone-substituted salicylic aldehydes and indoles using In(OTf)₃ as a catalyst. The method has the advantages of simple operation, mild reaction conditions, and friendly environment.

Topics: Aldehydes; Indoles; Mesylates; Naphthoquinones; Salicylates; Solvents

The fatty acid biosynthesis (FAS II) is a vital process in bacteria and regarded as an attractive pathway for the development of potential antimicrobial agents. In this study, we report 1,4-naphthoquinone (NPQ) as a dual inhibitor of two key enzymes of FAS II pathway, namely FabD (Malonyl-CoA:ACP transacylase) and FabZ (β-hydroxyacyl-ACP dehydratase). Mode of inhibition of NPQ was found to be non-competitive for both enzymes with IC

Topics: Acyl-Carrier Protein S-Malonyltransferase; Anti-Bacterial Agents; Bacterial Proteins; Circular Dichroism; Malonyl Coenzyme A; Microbial Sensitivity Tests; Molecular Docking Simulation; Molecular Dynamics Simulation; Molecular Structure; Moraxella catarrhalis; Naphthoquinones; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Thermodynamics

Two new phytotoxic tetrasubstituted 1,4-naphthoquinones, named diploquinones A and B, were isolated together with vanillic acid from Diplodia mutila (DAR78993), a grapevine pathogen involved in Botryosphaeria dieback in Australia. Diploquinones A and B were characterized as 6,7-dihydroxy-2-methoxy-5-methylnaphthalene-1,4-dione and 3,5,7-trihydroxy-2-methoxynaphthalene-1,4-dione using spectroscopic methods (essentially 1D and 2D

Topics: Ascomycota; Molecular Structure; Mycotoxins; Naphthoquinones; Plant Diseases; Vitis

Streptococcus pneumoniae (the pneumococcus) is an opportunistic pathogen responsible for several human diseases, including acute otitis media, pneumonia, sepsis and bacterial meningitis, and possesses numerous virulence factors associated with pneumococcal infection and pathogenesis. With the capacity to form pores in cholesterol-rich membranes, pneumolysin (PLY) is a key virulence factor of S. pneumoniae and causes severe tissue damage during pneumococcal infection. Juglone (JG), a natural 1,4-naphthoquinone widely found in the roots, leaves, woods and fruits of Juglandaceae walnut trees, inhibits PLY-induced hemolysis via inhibition of the oligomerization of PLY and exhibits minimal anti-S. pneumoniae activity. In addition, when human alveolar epithelial (A549) cells were co-cultured with PLY and JG, PLY-mediated cell injury was significantly alleviated. These results indicate that JG directly interacts with PLY to reduce the cytotoxicity of the toxin in human alveolar epithelial cells. Hence, JG is an effective inhibitor of PLY and protects lung cells from PLY-mediated cell injury. This study also provides the basis for the development of anti-virulence drugs for the treatment of S. pneumoniae infections.

Topics: Alveolar Epithelial Cells; Bacterial Proteins; Humans; Naphthoquinones; Streptococcus pneumoniae; Streptolysins

The main goal of the present study was to evaluate the ecotoxicological effects of 1,4-naphthoquinone (1,4-NTQ), a natural-origin compound presenting nematicidal activity, that can be obtained from walnut husk, in plants and soil invertebrates, including non-target soil nematode communities. This research was part of an ongoing project that aims to develop environmentally-friendly nematicides obtained from agricultural residues. The battery of ISO tests included emergence and growth of corn (Zea mays) and rape (Brassica napus); avoidance with the earthworm Eisenia andrei and the collembolan Folsomia candida; and reproduction with the previous species plus the enchytraeid Enchytraeus crypticus. A novel soil nematode community assay was also performed. ISO tests and nematode assays were conducted using a natural uncontaminated soil that was spiked with a range of 1,4-NTQ concentrations. Toxicity of 1,4-NTQ was found for all test-species and the most sensitive were F. candida and E. andrei. After 7 days of exposure to 1,4-NTQ, nematode abundance decreased along the concentration gradient, and a partial recovery was observed after 14 days (1,4-NTQ <48 mg kg

Topics: Agriculture; Animals; Antinematodal Agents; Arthropods; Biological Assay; Ecotoxicology; Naphthoquinones; Oligochaeta; Soil; Soil Pollutants; Zea mays

Topics: Bronchi; Cell Line; Cell Membrane; Cell Survival; Epithelial Cells; Humans; Membrane Potential, Mitochondrial; Naphthoquinones; Particulate Matter; Respiratory Mucosa; Soot

Electrophiles can activate redox signal transduction pathways, through actions of effector molecules (e.g., kinases and transcription factors) and sensor proteins with low pKa thiols that are covalently modified. In this study, we investigated whether 1,4-naphthoquinone (1,4-NQ) could affect the phosphatase and tensin homolog (PTEN)-Akt signaling pathway and persulfides/polysulfides could modulate this adaptive response. Simultaneous exposure of primary mouse hepatocytes to Na

Topics: Animals; Cell Death; Cyclic AMP Response Element-Binding Protein; Female; Gene Expression Regulation; Hepatocytes; Mice; Mice, Inbred C57BL; Naphthoquinones; Phosphorylation; Primary Cell Culture; Protective Agents; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Signal Transduction; Sodium Compounds; Sulfides

Amino acids playing important roles in metabolic processes are often included in dietary supplements whose use has largely expanded over the last 20 years not only in patients with particular deficiencies, but also in athletes and even common people that want to enrich their regular daily diet. In the present study, a bare silica Kinetex core-shell 2.6μm HILIC column was used for separation of some important hydrophilic amino acids and amino acids-like molecules i.e., aspartic acid, creatine, carnitine, arginine and the tripeptide glutathione (GSH), by optimizing the chromatographic conditions for their determination in complex alimentary supplements. The contribution of partition, adsorption and ion exchange on the retention mechanism was studied by varying parameters such as water content and the counter-ion concentration in the mobile phase. Optimum conditions employed a Phenomenex Kinetex core-shell 2.6μm HILIC (100×4.6mm i.d.) column and a mobile phase of acetonitrile/potassium phosphate buffer (12.5mM; pH=2.8) 85:15, v/v, at the flow rate of 1.4mL/min, using UV detection at 200nm. A reference HPLC method for the selective determination of GSH by using 1,4-naphthoquinone as derivatization reagent was also introduced for comparative purposes. The developed HILIC method was validated and applied to the analysis of the considered compounds in dietary supplements. Interestingly, in some of the real samples, oxidized glutathione which is an inactive impurity of GSH, was found at the level of about 20%. The proposed study confirms the importance of simple analytical methods for a rigorous quality control of dietary supplements containing unstable active ingredients.

Topics: Amino Acids; Chromatography, High Pressure Liquid; Hydrophobic and Hydrophilic Interactions; Naphthoquinones

A series of 1,4-naphthoquinones (10a-10q) were synthesized and evaluated for anticancer activity. Compound 10e was identified as an inhibitor of Itch, a HECT domain-E3 ligase. In an evaluation of in vivo efficacy, 10e exhibited remarkable anticancer activity with TGI values of 98.3% and 100% at 25 mg/kg and 50 mg/kg orally daily, respectively, against human RPMI-8226 multiple myeloma xenograft. Treatment with 10e also showed a decrease of Itch level in human RPMI-8226 multiple myeloma cells. Thus 10e is a lead compound for further development of inhibitors targeting E3 ligase for treatment of multiple myeloma.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Humans; Male; Mice; Mice, Nude; Mice, SCID; Molecular Structure; Multiple Myeloma; Naphthoquinones; Neoplasms, Experimental; Repressor Proteins; Structure-Activity Relationship; Ubiquitin-Protein Ligases

Black carbon (BC) is a key component of atmospheric particles and has a significant effect on human health. BC can provide reactive sites and surfaces thus absorb quinones which were primarily generated from fossil fuel combustion and/or atmospheric photochemical conversions of PAHs. Oxidation could change the characteristics of BC and increase its toxicity. The comparison of lung damage in mice exposed to BC and 1,4-NQ-coated BC (1,4NQ-BC) particles is investigated in this study. Mice which were intratracheally instilled with particles have a higher expression of IL-1β, IL-6 and IL-33 in bronchoalveolar lavage fluid (BALF). Also, the IL-6, IL-33 mRNA expression in the lung tissue of mice instilled with 1,4NQ-BC were higher than that of mice instilled with BC. The pathology results showed that the lung tissue of mice instilled with 1,4NQ-BC particles have much more inflammatory cells infiltration than that of mice treated with BC. It is believed that the MAPK and PI3K-AKT pathway might be involved in the 1,4NQ-BC particles caused lung damage. Results indicated that 1,4NQ-BC particles in the atmosphere may cause more damage to health.

Topics: Air Pollutants; Animals; Bronchoalveolar Lavage Fluid; Carbon; Inflammation; Interleukins; Lung; Mice; Naphthoquinones; Phosphatidylinositol 3-Kinases; Soot

Topics: Cell Line, Tumor; Cell Nucleus; Chromatography, Liquid; Cysteine; DNA-Binding Proteins; Gene Expression Regulation; Heat Shock Transcription Factors; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Humans; Naphthoquinones; Oxidation-Reduction; Signal Transduction; Sulfhydryl Compounds; Sulfur; Tandem Mass Spectrometry

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has recently gained attention as an antiprotozoan and anticancer drug target. We have previously identified 2-phenoxy-1,4-naphthoquinone as an inhibitor of both Trypanosoma brucei and human GAPDH. Herein, through multiple chemical, biochemical, and biological studies, and through the design of analogs, we confirmed the formation of a covalent adduct, we clarified the inhibition mechanism, and we demonstrated antitrypanosomal, antiplasmodial, and cytotoxic activities in cell cultures. The overall results lent support to the hypothesis that 2-phenoxy-1,4-naphthoquinone binds the GAPDH catalytic cysteine covalently through a phenolate displacement mechanism. By investigating the reactivity of 2-phenoxy-1,4-naphthoquinone and its analogs with four GAPDH homologs, we showed that the covalent inhibition is not preceded by the formation of a strong non-covalent complex. However, an up to fivefold difference in inactivation rates among homologs hinted at structural or electrostatic differences of their active sites that could be exploited to further design kinetically selective inhibitors. Moreover, we preliminarily showed that 2-phenoxy-1,4-naphthoquinone displays selectivity for GAPDHs over two other cysteine-dependent enzymes, supporting its suitability as a warhead starting fragment for the design of novel inhibitors.

Topics: Antiprotozoal Agents; Glyceraldehyde-3-Phosphate Dehydrogenases; Humans; Malaria, Falciparum; Naphthoquinones; Plasmodium falciparum; Trypanocidal Agents; Trypanosoma brucei brucei

The compounds produced by a living organism are most commonly as medicinal agents and starting materials for the preparation of new semi-synthetic derivatives. One of the largest groups of natural compounds consists of products containing a 1,4-benzoquinone subunit. This fragment occurs in three enediyne antibiotics, dynemicin A, deoxydynemicin A, and uncilamicin, which exhibit high biological activity. A series of alkoxy derivatives containing 1,4-naphthoquinone, 5,8-quinolinedione, and 2-methyl-5,8-quinolinedione moieties was synthesized. Moreover, the 1,4-benzoquinone subunit was contacted with an enediyne fragment. All obtained compounds were characterized by spectroscopy and spectrometry methods. The resulting alkane, alkene, alkyne and enediyne derivatives were tested as antitumor agents. They showed high cytotoxic activity depending on the type of 1,4-benzoquinone subunit and the employed tumor cell lines. The synthesized derivatives fulfill the Lipinski Rule of Five and have low permeability through the blood-brain barrier.

Topics: Anthraquinones; Antineoplastic Agents, Phytogenic; Benzoquinones; Biological Products; Cell Line, Tumor; Cell Survival; Enediynes; Humans; Inhibitory Concentration 50; Naphthoquinones; Organ Specificity; Quinolines; Structure-Activity Relationship

Plasmodium falciparum (Pf) like most other organisms, has a sophisticated antioxidant system, part of which includes glutathione reductase (GR). GR works by recycling toxic glutathione disulfide to glutathione, thereby reducing reactive oxygen species and making a form of glutathione (GSH) the parasite can use. Inhibition of this enzyme in Pf impedes parasite growth. In addition, it has been confirmed that PfGR is not identical to human GR. Thus, PfGR is an excellent target for antimalarial drug development. A functional assay utilizing liquid chromatography-mass spectrometry was developed to specifically identify and evaluate inhibitors of PfGR. Using recombinant PfGR enzyme and 1,4-naphthoquinone (1) as a reference compound and 4-nitrobenzothiadiazole (2) and methylene blue (3) as additional compounds, we quantified the concentration of GSH produced compared with a control to determine the inhibitory effect of these compounds. Our results coincide with that presented in literature: compounds 1-3 inhibit PfGR with IC50 values of 2.71, 8.38, and 19.23 µm, respectively. Good precision for this assay was exhibited by low values of intraday and interday coefficient of variation (3.1 and 2.4%, respectively). Thus, this assay can be used to screen for other potential inhibitors of PfGR quickly and accurately.

Topics: Antimalarials; Chromatography, Liquid; Enzyme Assays; Enzyme Inhibitors; Glutathione; Glutathione Reductase; Humans; Malaria, Falciparum; Mass Spectrometry; Methylene Blue; Naphthoquinones; Plasmodium falciparum; Reproducibility of Results; Thiadiazoles

Previous reports have documented that 1,4-naphthoquinones act as inhibitors of the monoamine oxidase (MAO) enzymes. In particular, fractionation of the extracts of cured tobacco leafs has led to the characterization of 2,3,6-trimethyl-1,4-naphthoquinone, a non-selective MAO inhibitor. To derive structure-activity relationships for MAO inhibition by the 1,4-naphthoquinone class of compounds, this study investigates the human MAO inhibitory activities of fourteen structurally diverse 1,4-naphthoquinones of natural and synthetic origin. Of these, 5,8-dihydroxy-1,4-naphthoquinone was found to be the most potent inhibitor with an IC50 value of 0.860 μm for the inhibition of MAO-B. A related compound, shikonin, inhibits both the MAO-A and MAO-B isoforms with IC50 values of 1.50 and 1.01 μm, respectively. It is further shown that MAO-A and MAO-B inhibition by these compounds is reversible by dialysis. In this respect, kinetic analysis suggests that the modes of MAO inhibition are competitive. This study contributes to the discovery of novel MAO inhibitors, which may be useful in the treatment for disorders such as Parkinson's disease, depressive illness, congestive heart failure and cancer.

Topics: Kinetics; Molecular Docking Simulation; Monoamine Oxidase Inhibitors; Naphthoquinones; Structure-Activity Relationship

The method allowed simultaneous characterization of PAHs, nitro-PAHs and quinones in atmospheric particulate matter. This method employs a miniaturized micro-extraction step that uses 500 μL of an acetonitrile-dichloromethane mix and instrumental analysis by means of a high-resolution GC-MS. The method was validated using the SRM1649b NIST standard reference material as well as deuterated internal standards. The results are in good agreement with the certified values and show recoveries between 75% and 145%. Limit of detection (LOD) values for PAHs were found to be between 0.5 pg (benzo[a]pyrene) to 2.1 pg (dibenzo[a,h]anthracene), for nitro-PAHs ranged between 3.2 pg (1-nitrobenzo[e]pyrene) and 22.2 pg (3-nitrophenanthrene), and for quinones ranged between 11.5 pg (1,4-naphthoquinone) and 458 pg (9,10-phenanthraquinone). The validated method was applied to real PM10 samples collected on quartz fiber filters. Concentrations in the PM10 samples ranged from 0.06 to 15 ng m(-3) for PAHs, from

Topics: Air Pollutants; Benzo(a)pyrene; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Limit of Detection; Naphthoquinones; Particulate Matter; Polycyclic Aromatic Hydrocarbons; Solvents

The main objective of this work was to validate a label-free electrochemical method of protein detection using peptides as capture probes. As a proof-of-concept, we used a 7 amino acids sequence (HSSKLQL) specific for Prostate Specific Antigen. We investigated various electrografting conditions of two anilines (2-[(4-aminophenyl)sulfanyl]-8-hydroxy-1,4-naphthoquinone and 4-azidoaniline) further converted in situ into their corresponding diazonium salts on glassy carbon electrodes. It was demonstrated that the best method to obtain a mixed layer is the simultaneous electroreduction of the two diazonium salts. 4-azidoaniline was used to covalently immobilize the ethynyl-functionalized peptide probe by click coupling, and the hydroxynaphthoquinone derivative plays the role of electrochemical transducer of the peptide-protein recognition. The proteolytic activity of PSA towards a small peptide substrate carrying streptavidin at its distal end was also investigated to design an original sensing architecture leading to a reagentless, label free, and "signal-on" PSA sensor. Without optimization, the limit of quantification can be estimated in the nM to pM range.

Topics: Amino Acid Sequence; Aniline Compounds; Azo Compounds; Biosensing Techniques; Click Chemistry; Diazonium Compounds; Electrochemical Techniques; Electroplating; Humans; Male; Models, Molecular; Molecular Probes; Naphthoquinones; Oxidation-Reduction; Peptides; Prostate-Specific Antigen

The modification of DNA by adduct formation is a potential molecular initiating event of genotoxicity. A chemoassay was established to study adduct formation of electrophiles with deoxynucleosides. Liquid chromatography-mass spectrometry was used to determine the reactivity of the model electrophiles para-benzoquinone, hydroquinone, and 1,4-naphthoquinone with deoxynucleoside (deoxyadenosine (dA), deoxyguanosine (dG), deoxycytidine (dC) and thymidine (dT)) to detect formation of adducts via constant neutral loss scan of deoxyribose (116 Da), and to elucidate adduct structures using high resolution mass spectrometry. Of the four deoxynucleosides dG was most susceptible, followed by dC and para-benzoquinone was the most reactive electrophile. With this approach five dG and four dC adducts were detected, formed by Michael addition and subsequent condensation. Also oxidation occurred with reactive oxygen species (ROS). Three of the adducts formed by benzoquinone have not been reported before. This chemoassay combined with mass spectrometry offers a way (a) to screen a large number of chemicals for their genotoxic potential, (b) to determine novel adducts that may be searched for in in vitro and in vivo studies and thus (c) to better understand the reaction of electrophiles with nucleobases.

Topics: Benzoquinones; Chromatography, Liquid; Deoxyadenosines; Deoxycytidine; Deoxyguanosine; Deoxyribonucleosides; DNA; DNA Adducts; DNA Damage; Mutagens; Naphthoquinones; Oxidants; Tandem Mass Spectrometry; Thymidine

Five unknown compounds, morindaparvins C-G, consisting of naphthohydroquinones, a naphthoquinone, an anthraquinone, and a naphthohydroquinone dimer, together with three known quinones and seven other known compounds, were isolated from the aerial parts of Morinda parvifolia. The structures of morindaparvins C, D, E, F, and G were elucidated on the basis of spectroscopic or X-ray diffraction analysis as methyl 4-hydroxy-1,6-dimethoxy-naphthalene-2-carboxylate, methyl 4,8-dihydroxy-1-methoxy-naphthalene-2-carboxylate, 3-amino-6-methoxy-2-methoxycarbonyl-1,4-naphthoquinone, 1,4-dihydroxy-7-hydroxymethyl-anthraquinone, and dimethyl 1,1'-dihydroxy-4,4',7,7'-tetramethoxy-2,2'-binaphthalene-3,3'-dicarboxylate, respectively. Naphthoquinones and naphthohydroquinone dimers were previously unknown in the genus Morinda. In addition, the compounds were tested for cytotoxicity against four human cancer cell lines HeLa, A2780, Ketr3 and MCF-7 and their effects on p53-activated transcription. Three naphthoquinones had moderate cytotoxic effects with IC50 values ranging from 1.51 to 9.56 μM, through up-regulation of p53 transcriptional activity.

Topics: Anthraquinones; Antineoplastic Agents, Phytogenic; Crystallography, X-Ray; Drug Screening Assays, Antitumor; HeLa Cells; Humans; Male; Molecular Conformation; Molecular Structure; Morinda; Naphthoquinones; Plant Components, Aerial

Naphthalene-1,4-dione derivatives were synthesized and tested against selected bacterial strains. All the tested compounds were prepared by direct introduction of corresponding substituents into the naphthoquinone core in oxidative conditions. In this study, eight strains of bacteria (Proteus, Escherichia, Klebsiella, Staphylococcus, Enterobacter, Pseudomonas, Salmonella, Enterococcus) were used for determination of antimicrobial activity of synthesized compounds with the Minimal Inhibitory Concentration (MIC) method. Additionally, selected compounds were tested for haemolytic activity using human erythrocytes. All naphthalene-1,4-dione derivatives exhibited significant antimicrobial activity with MIC values between 7.8 and 500 μg/ml. A majority of the synthesized compounds showed the strongest antibacterial properties towards S. aureus, with a high level of selectivity. None of the tested naphthalene-1,4-dione derivatives exhibited haemolytic activity.

Topics: Anti-Bacterial Agents; Bacteria; Drug Design; Erythrocytes; Humans; Microbial Sensitivity Tests; Naphthoquinones

While it has long been believed that benzenes and naphthalenes are unable to activate the aryl hydrocarbon receptor (AhR) because they are poor ligands, we recently reported that these quinoid metabolites upregulated cytochrome P450 1A1 (CYP1A1) in Hepa1c1c7 cells (Abiko et al., 2015). In the current study, AhR activation, measured with a bioluminescence-based cell free assay, was induced by 1,2-naphthoquinone (1,2-NQ), a metabolite of naphthalene. Consistent with this, 1,4-benzoquinone (1,4-BQ), tert-butyl-1,4-BQ, and 1,4-NQ, as well as 1,2-NQ, all electrophilic mono- and bi-cyclic quinones, upregulated CYP1A1 mRNA and protein in HepG2 cells, whereas their parent aromatic hydrocarbons had little effect. Furthermore, immunofluorescence analysis confirmed that these quinones enhanced translocation of AhR to the nucleus.

Topics: Active Transport, Cell Nucleus; Aryl Hydrocarbon Receptor Nuclear Translocator; Basic Helix-Loop-Helix Transcription Factors; Benzoquinones; Cytochrome P-450 CYP1A1; Dose-Response Relationship, Drug; Enzyme Induction; Fluorescent Antibody Technique; Hep G2 Cells; Hepatocytes; Humans; Naphthoquinones; Quinones; Receptors, Aryl Hydrocarbon; RNA, Messenger; Transfection

A new phosphine-catalyzed [3+2] annulation reaction between activated 1,4-naphthoquinones and acetylenecarboxylates is described. This reaction provides a facile and efficient route to a variety of biologically promising and novel naphtho[1,2-b]furans. This devised method provides a first example for the synthesis of diverse naphtho[1,2-b]furan derivatives from 1,4-naphthoquinones via phosphine-catalyzed [3+2] annulation. A variety of novel naphtho[1,2-b]furans were synthesized via the phosphine-catalyzed [3+2] annulation of activated 1,4-naphthoquinones and electron-deficient acetylenecarboxylates. In some reactions, both furannulation adducts and reductive/nucleophilic conjugate addition products were produced.

Topics: Acetylene; Carboxylic Acids; Chemistry Techniques, Synthetic; Furans; Naphthoquinones; Phosphines

Bimolecular fluorescence-quenching reactions involving electron-transfer between electronically excited 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP*) and 1,4-benzoquinone (BQ) or 1,4-naphthoquinone (NQ) were investigated using a set of alkane solvents that enabled the rapid reaction kinetics to be probed over a wide viscosity range, while minimizing changes in other relevant solvent parameters. Relative diffusion coefficients and reaction distances were recovered directly from analysis of fluorescence decay curves measured on a nanosecond time scale. The electron transfer from TPP* to BQ requires reactant contact, consistent with tightly associated exciplex formation in these nonpolar solvents. In contrast, electron transfer from TPP* to NQ displays a clear distance dependence, indicative of reaction via a much looser noncontact exciplex. This difference is attributed to the greater steric hindrance associated with contact between the TPP*/NQ pair. The diffusion coefficients recovered from fluorescence decay curve analysis are markedly smaller than the corresponding measured bulk relative diffusion coefficients. Classical hydrodynamics theory was found to provide a satisfactory resolution of this apparent discrepancy. The calculated hydrodynamic radii of TPP and NQ correlate very well with the van der Waals values. The hydrodynamic radius obtained for BQ is a factor of 6 times smaller than the van der Waals value, indicative of a possible tight cofacial geometry in the (TPP(+)/BQ(-))* exciplex. The present work demonstrates the utility of a straightforward methodology, based on widely available instrumentation and data analysis, that is broadly applicable for direct determination of kinetic parameter values for a wide variety of rapid bimolecular fluorescence quenching reactions in fluid solution.

Topics: Alkanes; Benzoquinones; Diffusion; Electron Transport; Hydrodynamics; Naphthoquinones; Photochemical Processes; Porphyrins; Quantum Theory; Solvents

The aim of this study was to enhance the understanding of the antitumor mechanism of 1,4-naphthoquinones and ascorbate. Juglone, phenylaminonaphthoquinone-7, and 9 (Q7/Q9) were evaluated for effects on CT-DNA and DNA of cancer cells. Evaluations in MCF-7 cells are DNA damage, ROS levels, viability, and proliferation. Proteins from MCF-7 lysates were immunoblotted for verifying PARP integrity, γH2AX, and pAkt. Antitumor activity was measured in Ehrlich ascites carcinoma-bearing mice. The same markers of molecular toxicity were assessed in vivo. The naphthoquinones intercalate into CT-DNA and caused oxidative cleavage, which is increased in the presence of ascorbate. Treatments caused DNA damage and reduced viability and proliferation of MCF-7 cells. Effects were potentiated by ascorbate. No PARP cleavage was observed. Naphthoquinones, combined with ascorbate, caused phosphorylation of H2AX and inhibited pAkt. ROS were enhanced in MCF-7 cells, particularly by the juglone and Q7 plus ascorbate. Ehrlich carcinoma was inhibited by juglone, Q7, or Q9, but the potentiating effect of ascorbate was reproduced in vivo only in the cases of juglone and Q7, which caused up to 60% inhibition of tumor and the largest extension of survival. Juglone and Q7 plus ascorbate caused enhanced ROS and DNA damage and inhibited pAkt also in Ehrlich carcinoma cells.

Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Carcinoma, Ehrlich Tumor; Cell Line, Tumor; Cell Proliferation; Cell Survival; DNA Damage; Histones; Humans; Male; MCF-7 Cells; Mice; Mice, Inbred BALB C; Naphthoquinones; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species

Ambient particulate matter (PM) can cause adverse health effects via their ability to produce reactive oxygen species (ROS). Humic-like substances (HULIS), a complex mixture of amphiphilic organic compounds, have been demonstrated to contain the majority of redox activity in the water-extractable organic fraction of PM. Reduced organic nitrogen compounds, such as alkaloids resulting from biomass burning emissions, are among HULIS constituents. In this study, we examined the redox activities of pyridine, imidazole and their alkyl derivatives using a cell-free dithiothreitol (DTT) assay under simulated physiological conditions (37 °C, pH = 7.40). These compounds were found to have little redox activity on their own as measured by the DTT assay, but they enhanced ROS generation catalyzed by 1,4-naphthoquinone (as a model quinone compound) and HULIS isolated from multiple aerosol samples. The enhancement effect by the individual nitrogen-containing bases was determined to be proportional to their amount in the assay solutions. It is postulated that the underlying mechanism involves the unprotonated N atom acting as a H-bonding acceptor to facilitate hydrogen-atom transfer in the ROS generation cycle. The enhancement capability was found to increase with their basicity (i.e., pKa of their conjugated acids, BH(+)), consistent with the proposed mechanism for enhancement. Among the imidazole homologues, a linear relationship was observed between the enhancement factors (in log scale) of the unprotonated form of the imidazole compounds (B) and the pKa of their conjugated acids (BH(+)). This relationship predicts that the range of alkylimidazole homologues (C6-C13) observed in atmospheric HULIS would be 1.5-4.4 times more effective than imidazole in facilitating HULIS-mediated ROS generation. Our work reveals that the ability of atmospheric PM organics to catalyze generation of ROS in cells could be affected by coexisting redox inactive organic constituents and suggests further work deploying multiple assays be conducted to quantify redox capabilities and enhancement effects of the HULIS components.

Topics: Aerosols; Dithiothreitol; Humic Substances; Hydrogen Bonding; Imidazoles; Models, Theoretical; Naphthoquinones; Nitrogen; Oxidation-Reduction; Particulate Matter; Pyridines; Reactive Oxygen Species; Water

Recently, we established a biotin-PEAC5-maleimide (BPM)-labeling assay, which can be used to determine the modification of electrophilic metals to proteins (Toyama et al., J. Toxicol. Sci., 38, 477-484, 2013). In the present study, we applied a BPM-labeling assay to detect protein S-modification by environmental organic electrophiles. After exposing A431 cells to 1,2-naphthoquinone (1,2-NQ) and 1,4-naphthoquinone (1,4-NQ), there was an inverse correlation between Western blot analysis with specific antibody against these electrophiles and that with BPM on the blot intensity to detect protein modification. Similar results were also observed using enzyme-linked immunosorbent assay (ELISA) with BPM. Modification of proteins in mouse liver cytosol by 5-hydroxy-1,4-NQ, 5,8-dihydroxy-1,4-NQ, 1,4-benzoquinone (1,4-BQ), tert-butyl-1,4-BQ, and N-acetyl-p-benzoquinoneimine, an electrophilic metabolite of acetaminophen, was detected using ELISA, but not non-electrophilic quinones or hydroquinone. We also tested whether ELISA could be used to detect electrophiles contained in the vapor phase of ambient air samples collected in the midtown area of Los Angeles. Taken together, the results suggested that the ELISA, developed in this study, can detect the existence of electrophilic quinones that covalently modify cellular proteins, resulting in modulation of redox-signal transduction pathways or cell damage.

Topics: Animals; Biotin; Blotting, Western; Cytosol; Enzyme-Linked Immunosorbent Assay; Humans; Liver; Maleimides; Metals; Mice; Naphthoquinones; Oxidation-Reduction; Proteins; Quinones; Signal Transduction; Tumor Cells, Cultured; Volatilization

1,4-Dihydroxy-2-naphthoic acid was used as a substrate for a straightforward five-step synthesis of 3-substituted 1H-benzo[g]isochromene-5,10-diones, with a Michael addition of N-acylmethylpyridinium ylides across 2-hydroxymethyl-1,4-naphthoquinone and a subsequent acid-mediated dehydratation of intermediate hemiacetals as the key steps. The obtained benzo[g]isochromene-5,10-diones were subsequently deployed for further synthetic elaboration to produce new 3,4-dihydrobenzo[g]isochromene-5,10-diones and (3,4-dihydro-)4a,10a-epoxybenzo[g]isochromene-5,10-diones. All compounds were screened for their cytotoxic and antimicrobial effects, revealing an interesting cytotoxic activity of 1H-benzo[g]isochromene-5,10-diones against different cancer cell lines.

Topics: Anti-Infective Agents; Carboxylic Acids; Cell Line, Tumor; Drug Screening Assays, Antitumor; Epoxy Compounds; Humans; Inhibitory Concentration 50; Molecular Structure; Naphthalenes; Naphthoquinones; Structure-Activity Relationship

To examine the effect of hydrophobicity on the anticancer activity of 1,4-naphthoquinone derivatives, a series of compounds bearing a 2-O-alkyl-, 3-C-alkyl- or 2/3-N-morpholinoalkyl group were synthesized and evaluated for their anticancer activity against five human cancer cell lines in vitro. The cytotoxicity of these derivatives was assayed against HT-29, SW480, HepG2, MCF-7 and HL-60 cells by the MTT assay. Among them, 2-hydroxy-3-farnesyl-1,4-naphthoquinone (11a) was found to be the most cytotoxic against these cell lines. Our results showed that the effectiveness of compound 11a may be attributed to its suppression of the survival of HT-29. Secondly, in the Hoechst 33258 staining test, compound 11a-treated cells exhibited nuclear condensation typical of apoptosis. Additionally, cell cycle analysis by flow cytometry indicated that compound 11a arrested HT-29 cells in the S phase. Furthermore, cell death detected by Annexin V-FITC/propidium iodide staining showed that compound 11a efficiently induced apoptosis of HT-29 in a concentration-dependent manner. Taken together, compound 11a effectively inhibits colon cancer cell proliferation and may be a potent anticancer agent.

Topics: Cell Cycle; Cell Line, Tumor; Flow Cytometry; Humans; Lipids; Naphthoquinones; Neoplasms

The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines.. The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed.. C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 μm and 41 μm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level.. Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Cell Cycle Proteins; Cell Proliferation; Cell Survival; DNA Fragmentation; Dose-Response Relationship, Drug; HL-60 Cells; Humans; Inhibitory Concentration 50; K562 Cells; Leukemia; Membrane Potential, Mitochondrial; Molecular Structure; Naphthoquinones; Oxidative Stress; Reactive Oxygen Species; S Phase Cell Cycle Checkpoints; Structure-Activity Relationship; Triazoles

To study the effect of 1,4-naphthoquinone aged black carbon (BC/1,4-NQ) on reactive oxygen species and DNA strand breaks in human bronchial epithelial cells (16HBE).. In the study, 16HBE cells were exposed to BC/1,4-NQ, BC and 1,4-NQ at the concentrations of BC/1,4-NQ (10.0/0.2, 20.0/0.4, 40.0/0.8, 80.0/1.6, 160.0/3.2 mg/L), BC (10.0, 20.0, 40.0, 80.0, 160.0 mg/L), 1,4-NQ (0.2, 0.4, 0.8, 1.6, 3.2 mg/L) for 24, 48, and 72 h, respectively. Cytotoxicity was detected by cell count kit 8 (CCK-8) at the end point. Then the 16HBE cells were exposed to BC/1,4-NQ (20.0/0.4, 40.0/0.8, 80.0/1.6 mg/L), BC (20.0, 40.0, 80.0 mg/L), 1,4-NQ (0.4, 0.8, 1.6 mg/L) for 24 h. The reactive oxygen species (ROS) generation was determined via flow cytometry with DCFH-DA probe. Single cell gel electrophoresis (SCGE) assay was performed to evaluate genotoxicity by Olive tail moment (OTM) value.. Except for the concentration of 10.0/0.2 mg/L within the exposure time 24 h, the cell viabilities of BC/1,4-NQ were significantly lower than the control (P<0.05) within the exposure time 24-72 h, showing a dose-dependent cytotoxicity. Especially, BC/1,4-NQ showed greater cytotoxicity than BC single exposure, lower than 1,4-NQ at the concentration of BC/1,4-NQ≥80.0/1.6 mg/L. BC/1,4-NQ also showed greater ROS generation and OTM value than the control within the exposure time 24 h at each concentration (P<0.05). Especially, the ROS generation and OTM value of BC/1,4-NQ were greater than BC single exposure, lower than 1,4-NQ at the concentration of 80.0/1.6 mg/L (P<0.05).. BC/1,4-NQ can induce intracellular ROS generation, cytotoxicity and genotoxicity in 16HBE cells. And at high concentration, the intracellular ROS level, cytotoxicity and genotoxicity induced by BC/1,4-NQ were greater than those by BC single exposure, but lower than those by 1,4-NQ.

Topics: Cell Line; Cell Survival; DNA Damage; Epithelial Cells; Humans; Naphthoquinones; Reactive Oxygen Species; Soot

A novel series of 1,4-naphthoquinones (33-44) tethered by open and closed chain sulfonamide moieties were designed, synthesized and evaluated for their cytotoxic and antimalarial activities. All quinone-sulfonamide derivatives displayed a broad spectrum of cytotoxic activities against all of the tested cancer cell lines including HuCCA-1, HepG2, A549 and MOLT-3. Most quinones (33-36 and 38-43) exerted higher anticancer activity against HepG2 cell than that of the etoposide. The open chain analogs 36 and 42 were shown to be the most potent compounds. Notably, the restricted sulfonamide analog 38 with 6,7-dimethoxy groups exhibited the most potent antimalarial activity (IC₅₀ = 2.8 μM). Quantitative structure-activity relationships (QSAR) study was performed to reveal important chemical features governing the biological activities. Five constructed QSAR models provided acceptable predictive performance (Rcv 0.5647-0.9317 and RMSEcv 0.1231-0.2825). Four additional sets of structurally modified compounds were generated in silico (34a-34d, 36a-36k, 40a-40d and 42a-42k) in which their activities were predicted using the constructed QSAR models. A comprehensive discussion of the structure-activity relationships was made and a set of promising compounds (i.e., 33, 36, 38, 42, 36d, 36f, 42e, 42g and 42f) was suggested for further development as anticancer and antimalarial agents.

Topics: Antimalarials; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Hep G2 Cells; Humans; Molecular Structure; Naphthoquinones; Parasitic Sensitivity Tests; Plasmodium falciparum; Quantitative Structure-Activity Relationship; Sulfonamides

1,4-Naphthoquinone (1) and a new coumarin (3) were isolated from Ajania salicifolia, together with two known compounds (2, 4). The structures and stereochemistry of new compounds were elucidated using spectroscopic methods. Two compounds exhibited potent ABTS cation radical scavenging activities with IC50 values ranging 7.97-8.44 μM. Two quinones (1, 2) exhibited moderate cytotoxic activity against the human cancer cell lines (Hela, HepG2, and K562) with IC50 values of 11.24-35.15 μM in vitro. This is the first report of naphthoquinone in the genus Ajania.

Topics: Antineoplastic Agents, Phytogenic; Antioxidants; Asteraceae; Cell Survival; Coumarins; Drug Screening Assays, Antitumor; Free Radical Scavengers; HeLa Cells; Hep G2 Cells; Humans; Inhibitory Concentration 50; Molecular Structure; Naphthoquinones; Quinones

Monoamine oxidase (MAO) action has been involved in the regulation of neurotransmitters levels, cell signaling, cellular growth, and differentiation as well as in the balance of the intracellular polyamine levels. Although so far obscure, MAO inhibitors are believed to have some effect on tumors progression. 1,4-naphthoquinone (1,4-NQ) has been pointed out as a potential pharmacophore for inhibition of both MAO and DNA topoisomerase activities, this latter associated with antitumor activity. Herein, we demonstrated that certain antitumor 1,4-NQs, including spermidine-1,4-NQ, lapachol, and nor-lapachol display inhibitory activity on human MAO-A and MAO-B. Kinetic studies indicated that these compounds are reversible and competitive MAO inhibitors, being the enzyme selectivity greatly affected by substitutions on 1,4-NQ ring. Molecular docking studies suggested that the most potent MAO inhibitors are capable to bind to the MAO active site in close proximity of flavin moiety. Furthermore, ability to inhibit both MAO-A and MAO-B can be potentialized by the formation of hydrogen bonds between these compounds and FAD and/or the residues in the active site. Although spermidine-1,4-NQs exhibit antitumor action primarily by inhibiting topoisomerase via DNA intercalation, our findings suggest that their effect on MAO activity should be taken into account when their application in cancer therapy is considered.

Topics: Antineoplastic Agents; Catalytic Domain; Drug Delivery Systems; Enzyme Activation; Humans; Kinetics; Molecular Docking Simulation; Monoamine Oxidase; Monoamine Oxidase Inhibitors; Naphthoquinones; Protein Isoforms

Nanoparticles of noble metals belong to the most extensively studied colloidal systems in the field of nanoscience and nanotechnology. Silver nanoparticles of different sizes have been prepared with the chemical reduction method using sodium borohydride and characterized using optical absorption technique. Using optical absorption and fluorescence emission studies, the photo physical properties of 2-amino-3-bromo1, 4-naphthoquinone (ABNQ) on silver nanoparticle have been studied. Concentration of the silver nanoparticle has been evaluated and the particle size dependent interaction between silver nanoparticles and ABNQ has been studied. The fluorescence quantum yield of ABNQ with and without silver nanoparticles has been calculated. The Stern-Volmer quenching constants and the molar absorptivity have been evaluated.

Topics: Metal Nanoparticles; Methanol; Naphthoquinones; Optical Phenomena; Particle Size; Quantum Theory; Silver; Spectrometry, Fluorescence; Surface Plasmon Resonance

Our group has recently initiated a study on the development of new prototypes for bioreductive prodrugs, based on Co(III) complexes with the ligand 2,2'-bis(3-hydroxy-1,4-naphthoquinone), H2bhnq. The focus of this work is to investigate the dissociation of bhnq(-2) from the complex upon reduction, and the effects of pH, redox potential, oxygen concentration and nature of the auxiliary ligands on this reaction. The bhnq(2-) ligand is a "non-cytotoxic" agent that was chosen as a probe for the reactivity studies due to its suitable chromophoric properties, at the same time that it resembles more cytotoxic naphthoquinones relevant for cancer therapy. In this way, two Co(III) complexes [Co(bhnq)(L1)]BF4·H2O (1) and [Co(bhnq)(L2)]BF4·H2O (2) (L1=N,N'-bis(pyridin-2-ylmethyl)ethylenediamine and L2=N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine) were synthesized and fully characterized. The gallium analogs [Ga(bhnq)(L1)]NO3·3H2O (3) and [Ga(bhnq)(L2)]NO3·3H2O (4) were also prepared for helping with the assignments of the redox properties of the cobalt complexes and the structure of 2. Cyclic voltammetry analysis revealed a pH-independent quasi-reversible Co(III)/Co(II) process at -0.22 and -0.08V vs NHE for 1 and 2, respectively. An O2-dependent dissociation of bhnq(2-) was observed for the reaction of 1 with ascorbic acid. For 2, the dissociation of bhnq(2-) was found to be independent on the concentration of O2 and faster than in 1, with little influence of the pH on both complexes. The difference in reactivity between 1 and 2 and their redox properties, among other factors, suggests that 1 undergoes redox cycling, pointed out as a key feature for a prodrug to achieve hypoxic selectivity.

Topics: Cobalt; Computer Simulation; Crystallography, X-Ray; Gallium; Humans; Hydrogen-Ion Concentration; Ligands; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Prodrugs

Low levels of oxidative stress have been shown to activate Nrf-2, an important anti-inflammatory transcription factor, by us and also by several other investigators. Earlier we showed that pro-oxidants protect normal lymphocytes against radiation injury by activating Nrf-2. In the present study, we have investigated the effect of oxidative stress on immune responses and delineated the underlying mechanism. Hydrogen peroxide, tert-butylhydroquinone and 1,4-naphthoquinone (NQ) inhibited mitogen induced proliferation of lymphocytes. NQ also inhibited mitogen (Concanavalin A) induced cytokine secretion by murine T cells and lipopolysaccharide induced release of cytokines, nitric oxide and cyclooxygenase-2 expression by macrophages. NQ modulated cellular redox by decreasing GSH/GSSG ratio and the immunosuppressive effects of NQ were significantly abrogated by thiol containing antioxidants and not by non-thiol antioxidants. This redox perturbation led to activation of Nrf-2 pathway and inhibition of NF-κB. NQ treatment increased total protein S-thiolation, induced glutathionylation of KEAP-1 protein and decreased IKKβ levels in lymphocytes. Molecular docking studies revealed that NQ can disrupt KEAP-1/Nrf-2 interaction by directly blocking the binding site of Nrf-2 in the KEAP-1 protein. Further, inhibitors of Nrf-2 and HO-1 abrogated the anti-inflammatory effects of NQ. T cells isolated from spleen and gut associated lymphoid tissue of NQ administered mice also showed suppression of NF-κB activation and were hyporesponsive to mitogenic stimulation. These results demonstrate that pro-oxidants modulate inflammatory and immune responses via oxidative stress mediated KEAP-1 glutathionylation and IKKβ degradation.

Topics: Adaptor Proteins, Signal Transducing; Animals; Anti-Inflammatory Agents; Cell Line; Cell Proliferation; Cytokines; Cytoskeletal Proteins; Glutathione; Kelch-Like ECH-Associated Protein 1; Lymphocytes; Male; Mice; Mice, Inbred BALB C; Molecular Docking Simulation; Naphthoquinones; NF-E2-Related Factor 2; Nitric Oxide; Oxidative Stress

The objective of this research was to simultaneously analyze protein adducts of quinonoid metabolites of naphthalene and endogenous estrogen in serum albumin (Alb) derived from healthy pregnant women in Taiwan and to explore the correlations among them. The isomeric forms of cysteinyl adducts of naphthoquinones, including 1,2-naphthoquinone (1,2-NPQ) and 1,4-naphthoquinone (1,4-NPQ) as well as estrogen quinones, including estrogen-2,3-quinones (E2-2,3-Q) and estrogen-3,4-quinones (E2-3,4-Q), are characterized after adduct cleavage. Results showed that the median levels of cysteinyl adducts of 1,2-NPQ and 1,4-NPQ on serum albumin were 249-390 and 16.0-24.8 pmol g(-1), respectively. Logged levels of 1,2-NPQ-Alb were correlated with logged levels of 1,4-NPQ-Alb (correlation coefficient r = 0.551, P < 0.001). Cysteinyl adducts of E2-2,3-Q-1-S-Alb, E2-2,3-Q-4-S-Alb, and E2-3,4-Q-2-S-Alb were detected in all subjects with median levels at 275-435, 162-288, and 197-254 pmol g(-1), respectively. We also found a positive relationship between logged levels of E2-2,3-Q-4-S-Alb and those of E2-3,4-Q-2-S-Alb (r = 0.770, P < 0.001).We noticed that median levels of E2-2,3-Q-derived adducts (E2-2,3-Q-1-S-Alb plus E2-2,3-Q-4-S-Alb) in pregnant women were greater than those of E2-3,4-Q-2-S-Alb (∼2-3-fold). Taken together, this evidence lends further support to the theme that cumulative concentration of E2-3,4-Q is a significant predictor of the risk of breast cancer. Furthermore, we noticed that levels of 1,2-NPQ-Alb are positively associated with levels of E2-3,4-Q-2-S-Alb (r = 0.522, P < 0.001) and those of E2-2,3-Q-4-S-Alb (r = 0.484, P < 0.001). Overall, this evidence suggests that environmental exposure to polycyclic aromatic hydrocarbons may modulate estrogen homeostasis and enhance the production of reactive quinone species of endogenous estrogen in humans.

Topics: Adult; Benzoquinones; Biomarkers; Body Burden; Breast Neoplasms; Environmental Exposure; Estradiol; Female; Humans; Naphthalenes; Naphthoquinones; Polycyclic Aromatic Hydrocarbons; Pregnancy; Quinones; Serum Albumin; Taiwan

A new series of 2-(4-aminobenzosulfonyl)-5H-benzo[b]carbazole-6,11-dione derivatives, which has not been reported yet, has been synthesized from 1,4-naphthoquinone and 4-aminophenylsulfone involving an Michael addition, benzoylation and Pd catalyzed coupling. This set of compounds has been evaluated for in vitro cytotoxicity specifically against human cervical cancer cell line (SiHa) and most of the synthesized compounds exhibited good cytotoxic activity. Molecular docking of all the synthesized compounds was studied; among fourteen molecules docked compound 3 was the one with the best glide and E model score of -9.06 and -73.41, respectively which is close to the glide score of SAHA (standard). In all docked molecules, the compound 7a exhibits least glide and E model score of -2.97 and -71.02 respectively.

Topics: Binding Sites; Carbazoles; Catalytic Domain; Cell Line, Tumor; Cell Survival; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Molecular Docking Simulation; Naphthoquinones; Repressor Proteins; Sulfones

Indothiazinone (1), an indolyl thiazolyl ketone, was discovered in cultures of novel myxobacterial strain 706, recently isolated from compost in Germany. Molecular phylogenetic studies based on 16S rRNA gene sequences revealed strain 706 to be a representative of a new family of the Sorangiineae. A screening of the culture broth for antimicrobial metabolites followed by isolation and characterization of these compounds revealed six indole derivatives and a 1,4-naphthoquinone derivative. The structures were determined to be indothiazinone (1; 1H-indol-3-yl(1,3-thiazol-2-yl)methanone) and three 3-methylbuta-1,3-dien-1-yl-substituted indoles, indolyl ethanol 2 and the E- and Z-isomers of indolyl ethylidenehydroxylamine 4 and 5 by MS and NMR spectroscopic analyses. In the indolyl ethanol derivative 3 the unsaturated methylene group of the butadienyl residue was replaced by an oxygen atom to give the keto group of the butanone side chain. Further 1H-indol-3-ylacetonitrile (6) was identified, which was already known as a myxobacterial metabolite. 2-Hydroxyethyl-3-methyl-1,4-naphthoquinone (7) was recognized during dereplication as an antibiotic previously isolated from Actinoplanes capillaceus. Whereas 1, 4, 5, and 7 showed weak activity against yeasts and filamentous fungi, isomers 4 and 5 were weakly active against Gram-positive bacteria and mouse fibroblasts. Compound 6 is volatile, and 2 and 3 showed no activity in a number of assays.

Topics: Anti-Bacterial Agents; Germany; Gram-Positive Bacteria; Indoles; Microbial Sensitivity Tests; Molecular Structure; Myxococcales; Naphthoquinones; Nuclear Magnetic Resonance, Biomolecular; Stereoisomerism; Thiazoles

Six novel 5,6-fused hybrids such as dihydrobenzofuran-quinone (4a and 4b), benzofuran-quinone (5a and 5b) and chromene-quinone (6a and 6b) of juglone based 1,4-naphthoquinones were synthesized by employing a three step protocol with the cyclisation of o-allyl phenol as the key step. The anticancer activity of the newly synthesized compounds was evaluated in vitro against seven human cancer cell lines including cervix (ME-180 and HeLa), breast (MCF-7, MDA-MB-453 and MDA-MB-231), prostate (PC-3) and colon (HT-29) by using MTT assay. The screening results showed that majority of the synthesized compounds exhibited significant anticancer activity. In particular, compounds 6a and 6b showed potent activities than the standard drug etoposide against prostate and breast cancer cell lines respectively. Flow cytometric analysis revealed that compounds 6a and 6b induced apoptosis and arrested the cell cycle at G2/M phase in PC-3 and MDA-MB-453 cells respectively.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Chemistry Techniques, Synthetic; Drug Screening Assays, Antitumor; Humans; Naphthoquinones

A series of 2-substituted amino-3-chloro-1,4-naphthoquinone derivatives (3-12) were synthesized as anticancer agents and tested against four cancer cell lines including HepG2, HuCCA-1, A549 and MOLT-3. The most potent cytotoxic activity against the HepG2, HuCCA-1 and A549 cell lines was found to be m-acetylphenylamino-1,4-naphthoquinone (8) affording IC50 values of 4.758, 2.364 and 12.279 μM, respectively. On the other hand, p-acetylphenylamino-1,4-naphthoquinone (9) exhibited the most potent cytotoxic activity against the MOLT-3 cell line with an IC50 of 2.118 μM. Quantitative structure-activity relationship (QSAR) investigations provided good predictive performance as observed from cross-validated R of 0.9177-0.9753 and RMSE of 0.0614-0.1881. The effects of substituents at the 2-amino position on the naphthoquinone core structure and its corresponding influence on the cytotoxic activity were investigated by virtually constructing additional 1,4-naphthoquinone compounds (13-36) for which cytotoxic activities were predicted using equations obtained from the previously constructed QSAR models. Interpretation of informative descriptors from QSAR models revealed pertinent knowledge on physicochemical properties governing the cytotoxic activities of tested cancer cell lines. It is anticipated that the QSAR models developed herein could provide guidelines for further development of novel and potent anticancer agents.

Topics: Antineoplastic Agents; Cell Line; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Hep G2 Cells; Humans; Molecular Structure; Naphthoquinones; Quantitative Structure-Activity Relationship

The technology of non-water-soluble mediator anaerobic biological catalysis has attracted more and more attention in the field of environment technology. In this study, five kinds of quinonly compounds were grafted on the chloromethylation polystyrene macromolecular carrier by Friedel-Crafts reaction. Reaction factors of temperature and molar ratio for the 1,4-naphthoquinone grafting carrier were optimized, and the optimal temperature was 78 degreesC while the optimal molar ratio of 1, 4-naphthoquinone and chloromethylation polystyrene was 2: 1. Fourier infrared spectrum analysis confirmed that the quinone groups were successfully grafted on the macromolecular backbone chloromethylation polystyrene. Catalysis using the five kinds of quinonly materials as non-water-soluble redox mediators enhanced the biological denitrification rate and the decoloration of azo dyes, meanwhile these materials showed good reusability in the biodegradation of azo dye. This study developed a new method for the preparation of quinonly materials and revealed a new field in the technology of mediator catalysis.

Topics: Azo Compounds; Biodegradation, Environmental; Catalysis; Coloring Agents; Naphthoquinones; Oxidation-Reduction; Polystyrenes; Waste Disposal, Fluid; Wastewater

In an effort to establish new candidates with enhanced anticancer activity of 5-hydroxy-7-methyl-1,4-naphthoquinone scaffold (7-methyljuglone) previously isolated from the root extract of Euclea natalensis, a series of 7-methyljuglone derivatives have been synthesized and assessed for cytotoxicity on selected human cancer lines. These compounds were screened in vitro for anticancer activity on MCF-7, HeLa, SNO and DU145 human cancer cell lines by MTT assay. Most of them exhibited significant toxicity on cancer cell lines with lower IC50 values. The most potent derivative (19) exhibited the toxicity on HeLa and DU145 cell lines with IC50 value of 5.3 and 6.8μM followed by compound (5) with IC50 value of 10.1 and 9.3μM, respectively. Structure-activity relationship reveals that the fluoro substituents at position C-8 while hydroxyl substituents at C-2 and C-5 positions played an important role in toxicity.

Topics: Antineoplastic Agents; Cell Cycle; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; HeLa Cells; Humans; MCF-7 Cells; Molecular Structure; Naphthoquinones; Structure-Activity Relationship; Tumor Cells, Cultured; U937 Cells

A Rh-catalyzed oxidative dehydrogenative cross-coupling of 1,4-naphthquinones with alkenes was achieved by using a substituent-enabled C(sp(2))-H functionalization (SEF) strategy. The method shows high functional group tolerance, broad substrate scope, and great potential for further functional transformations.

Topics: Alkenes; Catalysis; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Rhodium

A general method for the synthesis of a library of hitherto unreported amino-1,4-naphthoquinone-appended triazoles was accomplished via a sequential three-component reaction of substituted N-propargylaminonaphthoquinones with variously substituted alkyl bromides/2-bromonaphthalene-1,4-dione and sodium azide in the presence of Et3N/CuI in water. Aminonaphthoquinone-appended iminochromene-triazole hybrid heterocycles were also synthesized from the amino-1,4-naphthoquinone-appended-1,2,3-triazolylacetonitriles. All the triazole hybrids were screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB). Among the triazoles, 2-(((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)(4-(trifluoromethyl)phenyl)amino)naphthalene-1,4-dione (7d) emerged as the most active one with IC50 = 1.87 μM, being more potent than the anti-TB drugs, cycloserine (6 times), pyrimethamine (20 times) and equipotent as the drug ethambutol (IC50 < 1.56 μM).

Topics: Antitubercular Agents; Benzopyrans; Chemistry Techniques, Synthetic; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Naphthoquinones; Triazoles

1,4-Naphthoquinone is an active metabolite of naphthalene and it is also found in diesel exhaust particles. It is known to cause oxidative stress. In this study, we characterized 1,4-naphthoquinone-mediated cytotoxicity and its effects on the levels of non-protein thiols and intracellular Zn(2+) in rat thymocytes (thymic lymphocytes) by using 5-chloromethylfluorescein (5-CMF) fluorescence and FluoZin-3 fluorescence, respectively. Low concentrations of 1,4-naphthoquinone (0.3μM) increased the intensity of 5-CMF fluorescence, which is used to measure non-protein thiols. In contrast, 5-CMF intensity decreased at higher concentrations (1-3μM) of 1,4-naphthoquinone. Removal of intracellular Zn(2+) attenuated the 1,4-naphthoquinone-induced augmentation of 5-CMF fluorescence. Additionally, 1,4-naphthoquinone (0.3-3μM) increased FluoZin-3 fluorescence, which is used to assess intracellular Zn(2+), in a concentration-dependent manner. The augmentation of FluoZin-3 fluorescence by 1,4-naphthoquinone was due to the release of intracellular Zn(2+), because the removal of extracellular Zn(2+) did not affect the augmentation of FluoZin-3 fluorescence. These results suggest that sublethal concentrations of 1,4-naphthoquinone (0.3-1μM) affect the cellular levels of non-protein thiols and intracellular Zn(2+). The difference in the observed decrease in cellular thiol content due to 1,4-naphthoquinone treatment and increase due to Zn(2+) release following 1,4-naphthoquinone treatment likely confers the change in cellular thiol content. Further, the increase in intracellular Zn(2+) concentration after 1,4-naphthoquinone exposure may change the activity of thymocytes because thymulin, a thymus-specific hormone, requires Zn(2+) for its biological activity.

Topics: Animals; Cell Survival; Fluoresceins; Fluorescent Dyes; Naphthoquinones; Oxidative Stress; Polycyclic Compounds; Rats; Rats, Wistar; Sulfhydryl Compounds; Thymocytes; Zinc

This paper describes a novel series of N,O-acetals and N,S-acetals (7a-o) derived from 2-amino-1,4-naphthoquinones that were synthesized and evaluated as potential antimicrobial agents. These compounds were obtained in good yields using microwave irradiation, and several of them showed promising antibacterial profiles. Three of our biologically active 2-amino-1,4-naphthoquinone N,O-acetals and N,S-acetals tested against hospital bacterial strains were identified as potential lead compounds. Characterization of all compounds was performed using one-dimensional NMR techniques ((1)H, (13)C-APT), IR spectra, elemental analyses and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS).

Topics: Acetals; Anti-Bacterial Agents; Gram-Negative Bacteria; Gram-Positive Bacteria; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Microwaves; Models, Chemical; Molecular Structure; Naphthoquinones; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Infrared

Investigating the role of drugs whose pharmaceutical activity is associated with cell membranes is fundamental to comprehending the biochemical processes that occur on membrane surfaces. In this work, we examined the action of 1,4-naphthoquinone in lipid Langmuir monolayers at the air-water interface, which served as a model for half of a membrane, and investigated the molecular interactions involved with tensiometry and vibrational spectroscopy. The surface pressure-area isotherms exhibited a noticeable shift to a lower area in relation to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine (DPPS) lipid monolayers, which indicated a disruption of the monolayer structure and solubilisation of the lipids towards the aqueous subphase. To better correlate to the action of this drug in biological membrane events, cell cultures that represented tumorigenic and non-tumorigenic cells were spread onto the air-water interface, and 1,4-naphthoquinone was then incorporated. While only slight changes were observed in the non-tumorigenic cells upon drug incorporation, significant changes were observed in the tumorigenic cells, on which the organisation of the Langmuir monolayers was disrupted as evidenced by tensiometry and vibrational spectroscopy. This work then shows that this drug interacts preferentially for specific surfaces. In simplified models, it has a higher effect for the negative charged DPPS rather than the zwitterionic DPPC; and for complex cell cultures, 1,4-naphthoquinone presents a more significant effect for that representing tumorigenic cells.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Animals; Cell Line, Transformed; Cell Membrane; Membranes, Artificial; Models, Chemical; Naphthoquinones; Phosphatidylserines; Rabbits; Surface Tension

We used iodo-Bodipy derivatives that show strong absorption of visible light and long-lived triplet excited states as organic catalysts for photoredox catalytic organic reactions. Conventionally most of the photocatalysts are based on the off-the-shelf compounds, usually showing weak absorption in the visible region and short triplet excited state lifetimes. Herein, the organic catalysts are used for two photocatalyzed reactions mediated by singlet oxygen ((1)O2), that is, the aerobic oxidative coupling of amines and the photooxidation of dihydroxylnaphthalenes, which is coupled to the subsequent addition of amines to the naphthoquinones, via C-H functionalization of 1,4-naphthoquinone, to produce N-aryl-2-amino-1,4-naphthoquinones (one-pot reaction), which are anticancer and antibiotic reagents. The photoreactions were substantially accelerated with these new iodo-Bodipy organic photocatalysts compared to that catalyzed with the conventional Ru(II)/Ir(III) complexes, which show weak absorption in the visible region and short-lived triplet excited states. Our results will inspire the design and application of new organic triplet photosensitizers that show strong absorption of visible light and long-lived triplet excited state and the application of these catalysts in photoredox catalytic organic reactions.

Topics: Amines; Boron Compounds; Catalysis; Molecular Structure; Naphthalenes; Naphthoquinones; Oxidation-Reduction; Photochemical Processes; Photosensitizing Agents; Singlet Oxygen

When produced at physiological levels, reactive oxygen species (ROS) can act as signaling molecules to regulate normal vascular function. Produced under pathological conditions, ROS can contribute to the oxidative damage of cellular components (e.g., DNA and proteins) and trigger cell death. Moreover, the reaction of superoxide with nitric oxide (NO) produces the strong oxidant peroxynitrite and decreases NO bioavailability, both of which may contribute to activation of cell death pathways. The effects of ROS generated from the 1,4-naphthoquinones alone and in combination with NO on the activation status of poly(ADP-ribose) polymerase (PARP) and cell viability were examined. Treatment with redox cycling quinones activates PARP, and this stimulatory effect is attenuated in the presence of NO. Mitochondria play a central role in cell death signaling pathways and are a target of oxidants. We show that simultaneous exposure of endothelial cells to NO and ROS results in mitochondrial dysfunction, ATP and NAD(+) depletion, and cell death. Alone, NO and ROS have only minor effects on cellular bioenergetics. Further, PARP inhibition does not attenuate reduced cell viability or mitochondrial dysfunction. These results show that concomitant exposure to NO and ROS impairs energy metabolism and triggers PARP-independent cell death. While superoxide-mediated PARP activation is attenuated in the presence of NO, PARP inhibition does not modify the loss of mitochondrial function or adenine and pyridine nucleotide pools and subsequent bioenergetic dysfunction. These findings suggest that the mechanisms by which ROS and NO induce endothelial cell death are closely linked to the maintenance of mitochondrial function and not overactivation of PARP.

Topics: Animals; Aorta; Cattle; Cell Death; Cells, Cultured; Endothelium, Vascular; Energy Metabolism; Mitochondria; Naphthoquinones; Nitric Oxide; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Reactive Oxygen Species

The synthesis of optically active, carboannulated dihydronaphthoquinone and naphthoquinone derivatives with up to four stereogenic centers is demonstrated by H-bond-directed, trienamine-mediated [4 + 2]-cycloadditions. The outcome of the reaction between 2,4-dienals and 1,4-naphthoquinones is controlled by the substituent in the 2-position of the 1,4-naphthoquinone. In the case of sterically demanding 2-substituted derivatives, dihydronaphthoquinones are obtained. However, when a hydrogen atom is present in the 2-position, a subsequent oxidation of the initially formed cycloadducts occurs yielding naphthoquinones.

Topics: Alkenes; Hydrogen Bonding; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Stereoisomerism

The dependence of fluorescence emission of 2-amino-3-bromo-1,4-naphthoquinone on titanium dioxide (TiO2) in methanol has been investigated. The increase in TiO2 concentration causes a decrease in the fluorescence intensity of 2-amino-3-bromo-1,4-naphthoquinone. A linear Stern-Volmer plot in this study indicates the presence of dynamic quenching. The quenching and association constants have been calculated. The quenching process is due to the electron transfer from 2-amino-3-bromo-1,4-naphthoquinone to TiO2.

Topics: Amination; Amines; Fluorescence; Halogenation; Methanol; Naphthoquinones; Spectrometry, Fluorescence; Titanium

In this paper, we report the structure-activity relationship studies of substituted 1,4-naphthoquinones for its anticancer properties. 1,4-Naphthoquinone, Juglone, Menadione, Plumbagin and LLL12.1 were used as lead molecules to design PD compounds. Most of the PD compounds showed improved antiproliferative activity in comparison to the lead molecule in prostate (DU-145), breast (MDA-MB-231) and colon (HT-29) cancer cell lines. PD9, PD10, PD11, PD13, PD14 and PD15 were found to be the most potent compound with an IC₀ value of 1-3 μM in all cancer cell lines. Fluorescent polarization assay was employed to study the inhibition of STAT3 dimerization by PD compounds. PD9 and PD18 were found to be potent STAT3 dimerization inhibitors.

Topics: Antineoplastic Agents; Cell Line, Tumor; Drug Screening Assays, Antitumor; HT29 Cells; Humans; Models, Molecular; Naphthoquinones; Structure-Activity Relationship

1,4-Naphthoquinone derivatives are known to have relevant activities against several parasites. Among the treatment options for malaria, atovaquone, a 1,4-naphthoquinone derivative, is widely applied in the treatment and prophylaxis of such disease. Based on the structure simplification of atovaquone, we designed and synthesized four novel naphthoquinoidal derivatives. The compounds were obtained by the underexplored epoxide-opening reaction of 1,4-naphthoquinone using aniline derivatives as nucleophiles. The antiplasmodial activity of the synthesized compounds was performed in vivo using Peter's 4days suppression test. Significant parasitemia reduction and increased survival were observed for some of the compounds.

Topics: Animals; Antimalarials; Epoxy Compounds; Malaria; Mice; Molecular Structure; Naphthoquinones; Plasmodium falciparum; Survival Analysis

Three-component coupling of aldehyde, 2-hydroxy-1,4-naphthoquinone and 3-amino-1,2,4-triazole has been achieved using a catalytic amount of sulfamic acid under solvent free conditions to produce a novel series of 6-aryl-benzo[h][1,2,4]-triazolo[5,1-b]quinazoline-7,8-dione derivatives in good yields and with high regioselectivity. These compounds are found to exhibit potent antitumoral properties.

Topics: Aldehydes; Antineoplastic Agents; Catalysis; Cell Line, Tumor; Hep G2 Cells; Humans; Naphthoquinones; Neoplasms; Quinazolines; Sulfonic Acids; Triazoles

A novel approach was developed for the synthesis of diverse dihydronaphtho[1,2-b]furans from 1,4-naphthoquinones and olefins in the presence of ceric ammonium nitrate. This reaction provides a rapid route for the synthesis of a variety of dihydronaphtho[1,2-b]furans and naphtho[1,2-b]furans bearing different substituents. This methodology was also used to synthesize the biologically important natural product furomollugin in only 2 steps.

Topics: Alkenes; Biological Products; Catalysis; Cerium; Cyclization; Furans; Heterocyclic Compounds, 3-Ring; Molecular Structure; Naphthols; Naphthoquinones; Pyrones

Examination of electron transfer and proton transfer reactions of lumiflavin and proton transfer reactions of the lumiflavin radical anion by Fourier transform ion cyclotron resonance mass spectrometry is described. From the equilibrium constant determined for electron transfer between 1,4-naphthoquinone and lumiflavin the electron affinity of lumiflavin is deduced to be 1.86 ± 0.1 eV. Measurements of the rate constants and efficiencies for proton transfer reactions indicate that the proton affinity of the lumiflavin radical anion is between that of difluoroacetate (331.0 kcal/mol) and p-formyl-phenoxide (333.0 kcal/mol). Combining the electron affinity of lumiflavin with the proton affinity of the lumiflavin radical anion gives a lumiflavin hydrogen atom affinity of 59.7 ± 2.2 kcal/mol. The ΔG298 deduced from these results for adding an H atom to gas phase lumiflavin, 52.1 ± 2.2 kcal/mol, is in good agreement with ΔG298 for adding an H atom to aqueous lumiflavin from electrochemical measurements in the literature, 51.0 kcal/mol, and that from M06-L density functional calculations in the literature, 51.2 kcal/mol, suggesting little, if any, solvent effect on the H atom addition. The proton affinity of lumiflavin deduced from the equilibrium constant for the proton transfer reaction between lumiflavin and 2-picoline is 227.3 ± 2.0 kcal mol(-1). Density functional theory calculations on isomers of protonated lumiflavin provide a basis for assigning the most probable site of protonation as position 1 on the isoalloxazine ring and for estimating the ionization potentials of lumiflavin neutral radicals.

Topics: Anions; Cyclotrons; Electrons; Flavins; Fluoroacetates; Fourier Analysis; Gases; Hydrogen; Mass Spectrometry; Naphthoquinones; Picolines

An efficient synthesis of benzo[f]indole-4,9-diones has been achieved by copper(II)-catalyzed naphthoquinone sequential C,N-difunctionalization reactions with β-enaminones. New C-C and C-N bonds are easily formed in the reaction course. Copper(II) salt plays a dual role as Lewis acid and oxidative catalyst, and O2 acts as the terminal oxidant. The advantage of this reaction is the high atom economy with broad substrate scope and excellent yields. The reaction can be scaled up to using at least grams of substrates.

Topics: Catalysis; Copper; Indoles; Lewis Acids; Molecular Structure; Naphthoquinones; Oxidation-Reduction

STAT3 is constitutively active in a large variety of cancers. The search for STAT3 inhibitors led to the discoveries of LLLs 3 and 12, which are substituted anthraquinones. LLL12 is an extremely potent compound that exhibits high levels of antiproliferative activity. Herein the synthesis and evaluation of compounds containing either an anthraquinone or 1,4-naphthoquinone moiety are reported. Analogs were evaluated in several cancer cell lines. Interestingly, it was found that the anthraquinones did not follow the same trends as the 1,4-naphthoquinones in regards to potency. LLL12, which contains a sulfonamide at position 1, was found to be the most potent of the anthraquinones. In contrast, the methyl ketone and methyl ester derivatives (LLLs 3.1 and 5.1) were found to be the most potent of the 1,4-naphthoquinones. Selected 1,4-naphthoquinones were also evaluated in the STAT3 fluorescence polarization assay in order to evaluate their abilities to bind to the STAT3 SH2 domain. They were found to have similar affinities, and their activities suggest that STAT3 is one of their molecular targets.

Topics: Anthraquinones; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; HT29 Cells; Humans; Naphthoquinones; Protein Binding; STAT3 Transcription Factor; Structure-Activity Relationship

This study was undertaken to evaluate possible antiallergic effects of an extract of pigments from green sea urchin (Strongylocentrotus droebachiensis) shells. Effects were studied on animal models - guinea pig ileum contraction, rabbit eyes allergic conjunctivitis, and rabbit local skin irritation. The extract significantly reduced, in a dose-dependent manner, the histamine-induced contractions of the isolated guinea pig ileum with ID50 =1.2 µg/mL (in equivalents of spinochrome B), had an inhibitory effect on the model of ocular allergic inflammation surpassing the reference drug olopatadine, and did not show any irritating effect in rabbits. The extract predominantly contained polyhydroxy-1,4-naphthoquinone which would be responsible for the pharmacological activity. The active compounds of the extract were evaluated in silico with molecular docking. Molecular docking into H1R receptor structures obtained from molecular dynamic simulations showed that all spinochrome derivatives bind to the receptor active site, but spinochrome monomers fit better to it. The results of the present study suggest possibilities for the development of new agents for treating allergic diseases on the base of pigments from sea urchins shells.

Topics: Animal Shells; Animals; Anti-Allergic Agents; Conjunctivitis, Allergic; Dibenzoxepins; Disease Models, Animal; Dose-Response Relationship, Drug; Guinea Pigs; Histamine; Ileum; Male; Molecular Docking Simulation; Naphthoquinones; Olopatadine Hydrochloride; Pigments, Biological; Rabbits; Skin; Strongylocentrotus

Polycyclic aromatic hydrocarbons (PAHs) on virgin polystyrene (PS) and PS marine debris led us to examine PS as a source and sink for PAHs in the marine environment. At two locations in San Diego Bay, we measured sorption of PAHs to PS pellets, sampling at 0, 1, 3, 6, 9, and 12 months. We detected 25 PAHs using a new analytical method with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Several congeners were detected on samples before deployment. After deployment, some concentrations decreased (1,3-dimethylnaphthalene and 2,6-methylnaphthalene), while most increased [2-methylanthracene and all parent PAHs (PPAHs), except fluorene and fluoranthene], suggesting that PS debris is a source and sink for PAHs. When sorbed concentrations of PPAHs on PS are compared to the five most common polymers [polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP)], PS sorbed greater concentrations than PP, PET, and PVC, similar to HDPE and LDPE. Most strikingly, at 0 months, PPAHs on PS ranged from 8 to 200 times greater than on PET, HDPE, PVC, LDPE, and PP. The combination of greater PAHs in virgin pellets and large sorption suggests that PS may pose a greater risk of exposure to PAHs upon ingestion.

Topics: Chromatography, Gas; Ecosystem; Mass Spectrometry; Naphthalenes; Naphthoquinones; Plastics; Polycyclic Aromatic Hydrocarbons; Polystyrenes; Principal Component Analysis; Seawater; Waste Products; Water Pollution

It has been shown earlier that plumbagin, a naturally occurring naphthaquinone has specific anticancer activity in BRCA1 blocked ovarian cancer cells. Plumbagin can induce estrogen dependent cell signaling and apoptosis in BRCA1 blocked ovarian cancer cells. Being a reactive oxygen species (ROS) generator and apoptosis inducing agent, plumbagin has immense potential as a promising anticancer agent. In this study we analyzed whether there would be increased anticancer activity if the positions of the functional groups on plumbagin were altered and further to analyze the detailed molecular mechanism of action of the lead molecule. Methods like MTT assay, apoptosis analysis by flow cytometry, assessment of mitochondrial membrane potential-Δψm , suppression subtractive hybridization, microarray, molecular docking and estrogen receptor-DNA binding activity by electrophoresis mobility shift assay (EMSA) were adopted for assessing the anticancer activity. Consequently we found that, plumbagin was the most potent anticancer agent when compared to structurally related compounds. The anti-cancer activities were in the order plumbagin > 1,4-naphthaquinone > juglone > lawsone > menadione. Molecular docking studies showed that plumbagin could be well docked in the receptor ligand complex of TRAIL-DR5 complexes to activate the extrinsic pathway of apoptosis. Since the antiproliferative activity of plumbagin could be reduced by inhibiting ERα, we speculated that plumbagin interferes with the binding of ERα to ERE and we confirmed this by EMSA. This study clearly indicates that plumbagin can induce multiple pathways of apoptosis and cell cycle arrest in BRCA1 blocked cells compared to unblocked cells.

Topics: Antineoplastic Agents, Phytogenic; BRCA1 Protein; Breast Neoplasms; Cell Cycle Checkpoints; Drug Screening Assays, Antitumor; Estrogen Receptor alpha; Female; Gene Knockout Techniques; Humans; Membrane Potential, Mitochondrial; Molecular Docking Simulation; Naphthoquinones; Ovarian Neoplasms; Poly(ADP-ribose) Polymerases; Response Elements; Structure-Activity Relationship; Transcriptome

The use of 1,4-naphthoquinone as an advantageous pre-column reagent for liquid chromatography analysis of aliphatic thiol compounds is proposed. The compound reacts selectively in mild conditions (5 min at room temperature; pH 7.5) with thiol function. The resulting adducts were separated under isocratic conditions by using a reversed-phase column (C-12n) with a mobile phase corresponding to methanol/triethylammonium phosphate buffer (pH 3; 0.05 mol L(-1)) 65:35, v/v, at a flow rate of 0.4 mL min(-1) in presence of quercetin as internal standard. Detection was set at a wavelength of 420 nm. The effect of the derivatization reaction conditions on the N-acetylcysteine (NAC) reaction yield was investigated by a series of experiments. The yield of NAC derivative was found to be quantitative at a reagent thiol molar ratio of about 3 by comparison with an authentic specimen of synthesized NAC adduct, which was characterized by (1) H NMR, IR, and UV. Similar linear responses were observed by standard and placebo solutions (determination coefficient, 0.9998). The within- and between-day standard deviations (RSD) were ≤0.47 %. Recovery studies showed good results (100.03 %) with RSD 0.76 %. The limit of detection was about 20 pmol. The utility of the validated method for the determination of NAC in a new dietary supplement and commercial formulations is demonstrated.

Topics: Acetylcysteine; Chromatography, High Pressure Liquid; Dietary Supplements; Naphthoquinones; Pharmaceutical Preparations; Sulfhydryl Compounds

Benzophenone is a phototoxic compound with absorption maxima in the ultraviolet A (UVA) and ultraviolet B (UVB) range. Many benzophenone derivatives are known to be photosensitizing. On the other hand, 2-hydroxy-4-methoxybenzophenone is used as a photoprotective agent. The aim of the present study was to analyse a range of benzophenone derivatives and thus examine the effects of molecular changes in the benzophenone molecule on phototoxic behaviour. Phototoxicity was tested by an in vitro photohaemolysis test. The tested compounds were benzophenone itself and the derivatives 2-hydroxybenzophenone, 2-aminobenzophenone, 2-benzoylbenzoic acid, 3-hydroxybenzophenone, and 4-hydroxybenzo-phenone, as well as the structurally similar compounds 9-fluorenone, 9-fluorenone-2-carboxylic acid, cyclohexyl phenyl ketone, and 1,4-naphtho-quinone. It was shown that minor changes in molecular structure can result in highly different phototoxic characteristics.

Topics: Benzophenones; Cyclohexanes; Erythrocytes; Fluorenes; Hemolysis; Humans; In Vitro Techniques; Naphthoquinones; Photosensitizing Agents; Spectrophotometry; Ultraviolet Rays

Naphthoquinones are bioactive compounds widespread in nature that impact on several cellular pathways, including cell proliferation and survival, by acting as prooxidants and electrophiles. We have previously described the role of the synthetic isoxazole condensed 1,4-naphthoquinone derivative 1a in preventing apoptosis induced by distinct stimuli in several cell models. In addition, apoptosis regulators and executioners may control neural stem cell (NSC) fate, without involving cell death per se. Here, we hypothesize that 1a might also play a role in NSC fate decision. We found that exposure to 1a shifts NSC differentiation potential from neurogenic to gliogenic lineage and involves the generation of reactive oxygen species, without increasing cell death. Modulation of caspases and calpains, using cysteine protease inhibitors, failed to mimic 1a effects. In addition, incubation with the naphthoquinone derivative resulted in upregulation and nuclear translocation of antioxidant responsive proteins, Nrf2 and Sirt1, which in turn may mediate 1a-directed shift in NSC differentiation. In fact, antioxidants halted the shift in NSC differentiation potential from neurogenic to gliogenic lineage, while strongly reducing reactive oxygen species generation and Nrf2 and Sirt1 nuclear translocation in NSC exposed to 1a. Collectively, these data support a new role for a specific naphthoquinone derivative in NSC fate decision and underline the importance of redox environment control.

Topics: Animals; Antioxidants; Caspases; Cell Differentiation; Cell Line; Cell Lineage; Cysteine Proteinase Inhibitors; Intracellular Space; Mice; Naphthoquinones; Neural Stem Cells; Neuroglia; Neurons; Oxidation-Reduction; Reactive Oxygen Species; Sirtuin 1

In the last decades, a series of compounds, including quinones and polyphenols, has been described as having anti-fibrillogenic action on α-synuclein (α-syn) whose aggregation is associated to the pathogenesis of Parkinson's disease (PD). Most of these molecules act as promiscuous anti-amyloidogenic agents, interacting with the diverse amyloidogenic proteins (mostly unfolded) through non-specific hydrophobic interactions. Herein we investigated the effect of the vitamins K (phylloquinone, menaquinone and menadione), which are 1,4-naphthoquinone (1,4-NQ) derivatives, on α-syn aggregation, comparing them with other anti-fibrillogenic molecules such as quinones, polyphenols and lipophilic vitamins. Vitamins K delayed α-syn fibrillization in substoichiometric concentrations, leading to the formation of short, sheared fibrils and amorphous aggregates, which are less prone to produce leakage of synthetic vesicles. In seeding conditions, menadione and 1,4-NQ significantly inhibited fibrils elongation, which could be explained by their ability to destabilize preformed fibrils of α-syn. Bidimensional NMR experiments indicate that a specific site at the N-terminal α-syn (Gly31/Lys32) is involved in the interaction with vitamins K, which is corroborated by previous studies suggesting that Lys is a key residue in the interaction with quinones. Together, our data suggest that 1,4-NQ, recently showed up by our group as a potential scaffold for designing new monoamine oxidase inhibitors, is also capable to modulate α-syn fibrillization in vitro.

Topics: alpha-Synuclein; Antifibrinolytic Agents; Cell Nucleus; Humans; Magnetic Resonance Spectroscopy; Microscopy, Atomic Force; Naphthoquinones; Neurofibrils; Quinones; Vitamin K; Vitamin K 1; Vitamin K 2; Vitamin K 3

Malaria has been known as one of the major causes of morbidity and mortality on a large scale in tropical countries until now. In the past decades, many scientific groups have focused their attention on looking for ideal drugs to this disease. So far, this research area is still a hot topic. In the present study, the antimalarial activity of 1, 4- naphthoquinonyl derivatives was modeled by linear and nonlinear statistical methods, that is to say, by forward stepwise multilinear regression (MLR) and radial basis function neural networks (RBFNN). The derived QSAR models have been statistically validated both internally - by means of the Leave One Out (LOO) and Leave Many Out (LMO) crossvalidation, and Y-scrambling techniques, as well as externally (by means of an external test set). The statistical parameters provided by the MLR model were R(2) =0.7876, LOOq(2) =0.7068, RMS =0.3377, R0 2 =0.7876, k =1.0000 for the training set,and R(2) =0.7648, q(2) ext =0.7597, RMS=0.2556, R0 2=0.7598, k=1.0417 for the external test set. The RBFNN model gave the following statistical results, namely: R(2)=0.8338, LOOq(2)=0.5869, RMS=0.2781, R0 2 = 0.8335, k=1.0000 for the training set, and R(2) =0.7586, q(2) ext =0.7189, RMS=0.2788, R0 2=0.7129, k=1.0284 for the external test set. Overall, these results suggest that the QSAR MLR-based model is a simple, reliable, credible and fast tool for the prediction and virtual screening of 1, 4-naphoquinone derivatives with high antimalarial activity. In addition, the energies of the highest occupied molecular orbital were found to have high correlation with the activity.

Topics: Antimalarials; Humans; Malaria; Models, Biological; Naphthoquinones; Neural Networks, Computer; Plasmodium; Quantitative Structure-Activity Relationship

The discovery and development of essential drugs for Chagas disease is a major concern worldwide. New substituted 1,4-naphthoquinones were synthesized and tested against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. These products exhibited substantial activity against T. cruzi, especially 2-((8E,11Z)-heptadeca-8,11-dienyl)-3-hydroxynaphthalene-1,4-dione (9) with IC(50) of 7.8 μM.

Topics: Antiprotozoal Agents; Dose-Response Relationship, Drug; Drug Discovery; Molecular Structure; Naphthoquinones; Parasitic Sensitivity Tests; Trypanosoma cruzi

Carbonyl reductase 1 (CBR1 or SDR21C1) is a ubiquitously-expressed, cytosolic, monomeric, and NADPH-dependent enzyme. CBR1 participates in apoptosis, carcinogenesis and drug resistance, and has a protective role in oxidative stress, cancer and neurodegeneration. S-Nitrosoglutathione (GSNO) represents the newest addition to its diverse substrate spectrum, which includes a wide range of xenobiotics and endogenous substances. GSNO has also been shown to covalently modify and inhibit CBR1. The aim of the present study was to quantify and characterize the resulting modifications. Of five candidate cysteines for modification by 2 mM GSNO (positions 26, 122, 150, 226, 227), the last four were analyzed using MALDI-TOF/TOF mass spectrometry and then quantified using the Selected Reaction Monitoring Approach on hyphenated HPLC with a triple quadrupole mass spectrometer. The analysis confirmed GSNO concentration-dependent S-glutathionylation of cysteines at positions 122, 150, 226, 227 which was 2-700 times higher compared to wild-type CBR1 (WT-CBR1). Moreover, a disulfide bond between neighboring Cys-226 and Cys-227 was detected. We suggest a role of these two cysteines as a redox-sensitive cysteine pair. The catalytic properties of wild-type and enzyme modified with 2 mM GSNO were also investigated by steady state kinetic experiments with various substrates. GSNO treatment of CBR1 resulted in a 2-5-fold decrease in kcat with menadione, 4-benzoylpyridine, 2,3-hexanedione, daunorubicin and 1,4-naphthoquinone. In contrast, the same treatment increased kcat for substrates containing a 1,2-diketo group in a ring structure (1,2-naphthoquinone, 9,10-phenanthrenequinone, isatin). Except for 9,10-phenanthrenequinone, all changes in kcat were at least in part compensated for by a similar change in Km, overall yielding no drastic changes in catalytic efficiency. The findings indicate that GSNO-induced covalent modification of cysteine residues affects the kinetic mechanism of CBR1 both in terms of substrate binding and turnover rate, probably by covalent modification of Cys-226 and/or Cys-227.

Topics: Alcohol Oxidoreductases; Amino Acid Sequence; Cysteine; Daunorubicin; Hexanones; Humans; Kinetics; Molecular Sequence Data; Naphthoquinones; Oxidation-Reduction; Pyridines; S-Nitrosoglutathione; Vitamin K 3

Traffic-related particulate matter (PM) is associated with adverse health effects. Quinones present in the traffic-related PM are hypothesized to contribute to these harmful effects through reactive oxygen species (ROS) generation. However, the impacts of the traffic-related PM and quinones on inflammatory processes and genotoxic damages are less well known. In present study we aimed to examine the genotoxic and inflammatory impacts of organic extracts from traffic-related PM (oTRP) in human lung epithelial A549 cells, and reveal the contributions from quinones. Significant cytotoxicity and DNA damage were caused by oTRP. The pro-inflammatory genes, interleukin-6 (Il-6), interleukin-8 (Il-8) and tumor necrosis factor (Tnf), and two aromatic hydrocarbon receptor-regulated genes, Cyp1a1 and 1b1, were significantly up-regulated by oTRP. A concomitant increase in ROS was observed, suggesting that oTRP may mediate genotoxic and inflammatory effects through oxidative stress pathway. Second, the effects from two typical airborne quinones, 9,10-anthraquinone (AQ) and 1,4-naphthroquinone (NQ) were compared. NQ, but not AQ, induced significant DNA damage in A549 cells. NQ up-regulated Il-8, Tnf, and Mcp-1 genes, while AQ induced the expression of Rantes gene. These results suggest that the NQ and AQ may participate in the pro-inflammatory responses through releasing different types of cytokines/chemokines.

Topics: Air Pollutants; Anthraquinones; Cell Line, Tumor; Cell Survival; Comet Assay; Cytokines; DNA Damage; Epithelial Cells; Humans; L-Lactate Dehydrogenase; Lung; Naphthoquinones; Particulate Matter; Reactive Oxygen Species; RNA, Messenger; Vehicle Emissions

Naphthoquinones have been found to have a wide range of biological activities, including cytotoxicity to cancer cells. The secondary metabolites lapachol, α- and β-lapachone and a series of 25 related synthetic 1,4-naphthoquinones were screened against the oesophageal cancer cell line (WHCO1). Most of the compounds exhibited enhanced cytotoxicity (IC50 1.6-11.7 μM) compared to the current drug of choice cisplatin (IC50 = 16.5 μM). This study also established that the two new synthetic halogenated compounds 12a and 16a (IC50 = 3.0 and 7.3 μM) and the previously reported compound 11a (IC50 = 3.9 μM), were non-toxic to NIH3T3 normal fibroblast cells. Cell death of oesophageal cancer cells by processes involving PARP cleavage caused by 11a was shown to be associated with elevated c-Jun levels, suggesting a role for this pathway in the mechanism of action of this cohort of naphthoquinone compounds.

Topics: Animals; Antineoplastic Agents; Cell Death; Cell Line, Tumor; Cell Proliferation; Crystallography, X-Ray; Dose-Response Relationship, Drug; Esophageal Neoplasms; Humans; Mice; Models, Molecular; Molecular Structure; Naphthoquinones; NIH 3T3 Cells; Structure-Activity Relationship

Symmetrical and unsymmetrical 3-halo- or 3-methoxy- substituted 2-dibenzoylamino- 1,4-naphthoquinone analogs were synthesized with an average yield of 45% via sodium hydride promoted bis-acylation of 2-amino-3-chloro-1,4-naphthoquinone, 2-amino-3-bromo-1,4-naphthoquinone and 2-amino-3-methoxy-1,4-naphthoquinone.

Topics: Electrons; Molecular Conformation; Naphthoquinones

New 3-substituted 1-(3-hydroxyphenyl)-5-oxopyrrolidine derivatives containing hydrazone, azole, diazole, oxadiazole fragments, as well as 2-phenoxy- and 2,3-diphenoxy-1,4-naphthoquinone derivatives were synthesized. The structure of all compounds has been confirmed by NMR, IR, mass spectra, and elemental analysis data. Methyl 1-{3-[(3-chloro-1,4-dioxo-1,4-dihydro-2-naphthalenyl)oxy]phenyl}-5-oxo-3-pyrrolidinecarboxylate demonstrated potential antibacterial and antifungal activities as determined by diffusion and serial dilution methods, while N'-[(4-bromophenyl)methylidene]-1-{3-[(3-chloro-1,4-dioxo-1,4-dihydro-2-naphthalenyl)oxy]phenyl}-5-oxo-3-pyrrolidinecarbohydrazide and 2-{3-[4-(1,2,3-oxadiazol-5-yl)-2-oxo-1-pyrrolidinyl]phenoxy}-3-{3-[4-(1,3,4-oxadiazol-2-yl)-2-oxo- 1-pyrrolidinyl]phenoxy}naphthoquinone showed antifungal activity against Candida tenuis and Aspergillus niger at low concentrations, as determined by the serial dilution method. The substitution of the methoxy fragment by N-containing substituents in monophenoxy substituted naphthoquinones was found to decrease their activity against Mycobacterium luteum. Besides, introduction of the second phenoxy substituted fragment increased the antifungal activity against Candida tenuis and Aspergillus niger at lower concentrations.

Topics: Anti-Bacterial Agents; Antifungal Agents; Aspergillus niger; Candida; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Mycobacterium; Naphthalenes; Naphthoquinones; Oxadiazoles

Despite intensive research, there are very few reagents with which to modulate and dissect the mRNA splicing pathway. Here, we describe a novel approach to identify such tools, based on detection of the exon junction complex (EJC), a unique molecular signature that splicing leaves on mRNAs. We developed a high-throughput, splicing-dependent EJC immunoprecipitation (EJIPT) assay to quantitate mRNAs spliced from biotin-tagged pre-mRNAs in cell extracts, using antibodies to EJC components Y14 and eukaryotic translation initiation factor 4aIII (eIF4AIII). Deploying EJIPT we performed high-throughput screening (HTS) in conjunction with secondary assays to identify splicing inhibitors. We describe the identification of 1,4-naphthoquinones and 1,4-heterocyclic quinones with known anticancer activity as potent and selective splicing inhibitors. Interestingly, and unlike previously described small molecules, most of which target early steps, our inhibitors represented by the benzothiazole-4,7-dione, BN82685, block the second of two trans-esterification reactions in splicing, preventing the release of intron lariat and ligation of exons. We show that BN82685 inhibits activated spliceosomes' elaborate structural rearrangements that are required for second-step catalysis, allowing definition of spliceosomes stalled in midcatalysis. EJIPT provides a platform for characterization and discovery of splicing and EJC modulators.

Topics: Benzoquinones; Biotin; HEK293 Cells; HeLa Cells; High-Throughput Screening Assays; Humans; Immunoprecipitation; Naphthoquinones; RNA Precursors; RNA Splicing; RNA, Messenger; Spliceosomes; Thiazoles

Airborne quinones contribute to adverse health effects of ambient particles probably because of their ability to generate hydroxyl radicals (·OH) via redox cycling, but the mechanisms remain unclear. We examined the chemical mechanisms through which 1,4-naphthoquinone (1,4-NQ) induced ·OH, and the redox interactions between 1,4-NQ and ascorbate acid (AscH(2)). First, ·OH formation by 1,4-NQ was observed in cellular and acellular systems, and was enhanced by AscH(2). AscH(2) also exacerbated the cytotoxicity of 1,4-NQ in Ana-1 macrophages, at least partially due to enhanced ·OH generation. The detailed mechanism was studied in an AscH(2)/H(2)O(2) physiological system. The existence of a cyclic 1,4-NQ process was shown by detecting the corresponding semiquinone radical (NSQ·-) and hydroquinone (NQH(2)). 1,4-NQ was reduced primarily to NSQ·- by O2·- (which was from AscH(2) reacting with H(2)O(2)), not by AscH(2) as normally thought. At lower doses, 1,4-NQ consumed O2·- to suppress ·OH; however, at higher doses, 1,4-NQ presented a positive association with ·OH. The reaction of NSQ·- with H(2)O(2) to release ·OH was another important channel for OH radical formation except for Haber-Weiss reaction. As a reaction precursor for O2·-, the enhanced ·OH response to 1,4-NQ by AscH(2) was indirect. Reducing substrates were necessary to sustain the redox cycling of 1,4-NQ, leading to more ·OH and a deleterious end point.

Topics: Animals; Ascorbic Acid; Benzoquinones; Cell Death; Cell Line; Electron Spin Resonance Spectroscopy; Hydroxyl Radical; Macrophages; Mice; Models, Biological; Naphthoquinones; Oxidation-Reduction

The antitrypanosomal activities, cytotoxicity, and selectivity indices of eleven imido-substituted 1,4-naphthoquinone derivatives and nifurtimox have been studied. Compared to nifurtimox (IC(50) = 10.67 μM), all the imido-naphthoquinone analogs (IMDNQ1-IMDNQ11) are more potent on Trypanosoma cruzi with IC50 values ranging from 0.7 μM to 6.1 μM (p < 0.05). Studies of the cytotoxic activities of these compounds on a Balb/C 3T3 mouse fibroblast cell line revealed that four of these compounds, IMDNQ1, IMDNQ2, IMDNQ3, and IMDNQ10 displayed selectivity indices of 60.25, 53.97, 31.83, and 275.3, respectively, rendering them significantly (p < 0.05) more selective in inhibiting the parasite growth than nifurtimox (selectivity index = 10.86).

Topics: Animals; Cytotoxins; Mice; Mice, Inbred BALB C; Naphthoquinones; NIH 3T3 Cells; Trypanocidal Agents; Trypanosoma cruzi

The influence of ring size on the photobehaviour of condensed 1,4-naphthoquinone systems, such as pyrano- and furano-derivatives (1 and 2, respectively) has been investigated. The absorption spectra for both families of naphthoquinones reveal clear differences; in the case of 2 they extend to longer wavelengths. A solvatochromic red shift in polar solvents is consistent with the π,π* character of the S(0)→ S(1) electronic transition in all cases. Theoretical (B3LYP) analysis of the HOMO and LUMO Kohn-Sham molecular orbitals of the S(0) state indicates that they are π and π* in nature, consistent with the experimental observation. A systematic study on the efficiency of singlet oxygen generation by these 1,4-naphthoquinones is presented, and values larger than 0.7 were found in every case. In accordance with these results, laser flash photolysis of deoxygenated acetonitrile solutions led to the formation of detectable triplet transient species with absorptions at 390 and 450 nm (1) and at 370 nm (2), with φ(ISC) close to 1. Additionally, the calculated energies for the T(1) states relative to the S(0) states at UB3LYP/6-311++G** are ca. 47 kcal mol(-1) for 1 and 43 kcal mol(-1) for 2. A comparison of the geometrical parameters for the S(0) and T(1) states reveals a marked difference with respect to the arrangement of the exocyclic phenyl ring whilst a comparison of electronic parameters revealed the change from a quinone structure to a di-dehydroquinone diradical structure.

Topics: Acetonitriles; Lasers; Naphthoquinones; Photolysis; Quantum Theory; Singlet Oxygen; Solvents

In this study, we describe the antitumor activity of QO-1, one of the new 2-aryl-1,4-naphthoquinone-1-oxime methyl ether derivatives. QO-1 is a derivative of macarpine, a natural occurring product from Rutaceae plant. It could potently inhibit cell growth when tested on 19 cancer cell lines. To investigate its mechanism, two cell lines (HeLa and MCF-7) sensitive to QO-1 were selected. Based on flow cytometry, it was found to induce G(2)/M-phase arrest. Moreover, it could cause microtubule depolymerization both in vitro and in vivo. On the other hand, QO-1 activated spindle assembly checkpoint (SAC) proteins. Expression of Bub1, one of the SAC, was gradually increased, reaching a peak after 16 - 20 h, and then gradually decreased. Instead, QO-1 increased the sub-G(1) population, which suggested a cell death population. Actually, expression of Bcl-2 family proteins and activation of caspase-3/7 were evidences of apoptosis. Consistent with these results, cells with DNA fragmentation and multinucleated cells were increased time-dependently after QO-1 exposure. In conclusion, QO-1 has promising antitumor effects via microtubule depolymerization.

Topics: Apoptosis; Cell Cycle; Cell Line, Tumor; DNA Fragmentation; HeLa Cells; Humans; Methyl Ethers; Microtubules; Naphthoquinones; Tubulin Modulators

Here we report a series of 2-aryl-3-amino-1,4-naphthoquinones that generated reactive oxygen species (ROS) such as superoxide and hydrogen peroxide upon incubation in pH 7.4 under ambient aerobic conditions. ROS generation from these compounds was sensitive to structural modifications at the 3-amino position and a 2-aryl substituent promoted ROS generation. A number of these compounds were found to induce DNA damage in the presence of Cu(II) without any added reducing agent. Our data suggests that 2-aryl-3-amino-1,4-naphthoquinones' propensity to produce ROS correlated well with its DNA damage inducing ability. 2-Phenyl-3-pyrrolid-1-yl-1,4-naphthoquinone (22) was found to damage DNA at 1 μM suggesting that these compounds may have therapeutic relevance in targeting cancers which over-express Cu(II).

Topics: Copper; Deoxyribonucleases; DNA Damage; Hydrogen-Ion Concentration; Naphthoquinones; Plasmids; Reactive Oxygen Species

Improving the solubility of polysubstituted 1,4-naphthoquinone derivatives was achieved by introducing nitrogen in two different positions of the naphthoquinone core, at C-5 and at C-8 of menadione through a two-step, straightforward synthesis based on the regioselective hetero-Diels-Alder reaction. The antimalarial and the antischistosomal activities of these polysubstituted aza-1,4-naphthoquinone derivatives were evaluated and led to the selection of distinct compounds for antimalarial versus antischistosomal action. The Ag(II)-assisted oxidative radical decarboxylation of the phenyl acetic acids using AgNO(3) and ammonium peroxodisulfate was modified to generate the 3-picolinyl-menadione with improved pharmacokinetic parameters, high antimalarial effects and capacity to inhibit the formation of β-hematin.

Topics: Animals; Antimalarials; Hemin; Humans; Malaria, Falciparum; Methemoglobin; Mice; Naphthoquinones; Plasmodium falciparum; Quinolines; Schistosoma mansoni; Schistosomiasis mansoni; Schistosomicides; Solubility

New oxirane derivatives were synthesized using six naphthoquinones as the starting materials. Our biological results showed that these oxiranes acted as trypanocidal agents against Trypanosoma cruzi with minimal cytotoxicity in the VERO cell line compared to naphthoquinones. In particular, oxirane derivative 14 showed low cytotoxicity in a mammalian cell line and exhibited better activity against epimastigote forms of T.cruzi than the current drug used to treat Chagas disease, benznidazole.

Topics: Animals; Cell Death; Cell Survival; Chlorocebus aethiops; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Ethylene Oxide; Models, Molecular; Molecular Structure; Naphthoquinones; Parasitic Sensitivity Tests; Structure-Activity Relationship; Trypanocidal Agents; Trypanosoma cruzi; Vero Cells

While metabolic activation of naphthalene, yielding 1,2-naphthoquinone (1,2-NQ) and 1,4-NQ that can covalently bind to cellular proteins, has been recognized to be associated with its toxicity, the current consensus is that such electrophile-mediated covalent modification of sensor proteins with thiolate ions is also involved in activation of cellular signal transduction pathways for cellular protection against reactive materials. In the present study, we developed an immunochemical assay to detect cellular proteins adducted by 1,4-NQ. Dot blot analysis indicated that the antibody prepared against 1,4-NQ recognized the naphthalene moiety with the para-dicarbonyl group, rather than with the ortho-dicarbonyl group. Furthermore, little cross-reactivity of para-quinones with either a different number of aromatic rings (n = 1) or substituent groups was observed. With this specific antibody against 1,4-NQ, we identified nine target proteins of 1,4-NQ following exposure of human epithelial carcinoma cell line A431 to 1,4-NQ. Among them, heat shock protein 90 (HSP90) and HSP70 are of interest because covalent modification of these chaperones causes activation of heat shock factor-1, which plays a role in the cellular response against electrophiles such as 1,4-NQ. Thus, our method, which does not use radiolabeled compounds, would be applicable for exploring activation of electrophilic signal transduction pathways coupled to covalent modification of sensor proteins during exposure to naphthalene as well as 1,4-NQ.

Topics: Animals; Cell Line, Tumor; Electrophoresis, Polyacrylamide Gel; Female; Humans; Immunochemistry; Naphthoquinones; Protein Binding; Proteins; Rabbits; Signal Transduction

Treatment of benzannulated enediynyl alcohols with trifluoroacetic acid at room temperature promoted a cascade sequence of cyclization reactions, leading to 1,4-naphthoquinone methides. The transformation involved an unusual two-carbon ring expansion from the cyclic alcohols and the construction of the p-quinone methide ring from an acyclic system along the reaction pathway.

Topics: Acids; Alcohols; Benzene; Catalysis; Cyclization; Enediynes; Indolequinones; Models, Molecular; Molecular Structure; Naphthoquinones

Previously, we reported that vitamin K(3), which consists of a quinone component, inhibits the activity of human DNA polymerase γ (pol γ). In this study, we investigated the inhibitory effects of 4 quinone derivatives (1,4-benzoquinone (BQ), 1,4-naphthoquinone (NQ), 9,10-anthraquinone (AQ) and 5,12-naphthacenequinone (NCQ)) on the activity of mammalian pols. BQ and NQ potently inhibited the activity of all the pol species: pols α, β, γ, δ, ε and λ, and NQ was a stronger pol inhibitor than BQ. Because we previously found a positive relationship between pol l inhibition and anti-inflammatory action, we examined whether these quinone derivatives could inhibit inflammatory responses. BQ and NQ caused a marked reduction in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced acute inflammation in mouse ear, although AQ and NCQ did not. In a cell culture system using mouse macrophages, NQ displayed the strongest suppression in the production of tumor necrosis factor (TNF)-α induced by lipopolysaccharide (LPS) among the quinone derivatives tested. Moreover, NQ was found to inhibit the action of nuclear factor (NF)-κ. In an in vivo mouse model of LPS-evoked acute inflammation, intraperitoneal injection of BQ and NQ to mice led to suppression of TNF-α production in serum. These anti-inflammatory responses of NQ were more potent than those of BQ. In conclusion, this study has identified several quinone derivatives, such as NQ, that are promising anti-inflammatory candidates.

Topics: Animals; Anthraquinones; Anti-Inflammatory Agents, Non-Steroidal; Antifibrinolytic Agents; Cattle; Cell Line; DNA-Directed DNA Polymerase; Enzyme Inhibitors; Female; Genes, pol; Humans; Inflammation; Macrophages; Mice; Mice, Inbred C57BL; Naphthoquinones; Nucleic Acid Synthesis Inhibitors; Rats; Vitamin K 3

Eleven 1,4-naphthoquinone analogues with different amino substitutions at position 3 of the quinone ring earlier reported for macrofilaricidal activity were selected and screened against purified cytosolic GST isolated from the bovine filarial worm Setaria digitata and IC(50) values were determined. Of the 11 compounds tested, 8 showed good inhibition against S. digitata GST. The IC(50) values of the most effective macrofilaricidal compounds-11 [2-(4-methylpiperazin-1-yl)naphthalene-1,4-dione] and 9 {2-[(1,3-dimethylbutyl)amino]naphthalene -1,4-dione}-were 0.872 and 0.994 mM, respectively. Compounds 9 and 11 were further studied for type of enzyme inhibition and found to exhibit competitive and uncompetitive inhibition kinetics, respectively, with respect to substrate GSH. All 11 compounds were in agreement with Lipinski's rule of five and passed through the FAFDrugs ADME/tox filter. Molecular docking was carried out using the modeled 3D structure of wbGST PDB ID:1SFM as receptor and substituted naphthoquinones as ligands using AutoDock 4.0. The binding energy of nine compounds varied from -9.15 to -6.58 Kcal mol(-1), whereas compounds 8 and 10 did not show any binding to the receptor. Among the compounds studied, compound 7 {2-[3-(diethylamino) propyl]aminonaphthalene-1,4-dione} showed maximum affinity towards wbGST as it exhibited the lowest binding energy, followed by compounds 11 and 9. However compound 7 was not macrofilaricidal while 11 and 9 exhibited macrofilaricidal activity. The results of in silico and in vitro studies with the synthesized 1,4 -naphthoquinone analogues on filarial GST and in vitro macrofilaricidal activity against adult bovine filarial worm S. digitata open up a promising biochemical target for antifilarial drug development.

Topics: Animals; Cattle; Enzyme Inhibitors; Female; Filaricides; Glutathione Transferase; Hydrogen Bonding; Models, Molecular; Molecular Conformation; Naphthoquinones; Protein Binding; Setaria Nematode

Preliminary examination for the structure-activity relationship of quinone monooxime derivatives on cytotoxicity against HeLa S3 cell and further trials using eight different cell lines suggested that 2-aryl-6,7-methylenedioxy-1,4-naphthoquinone-1-oxime methyl ethers, carrying 2-methoxy-4,5-methylenedioxyphenyl, 7-methoxy-2-methylbenzofuran-4-yl, and 2-methoxycarbonyl-3,4-dimethoxyphenyl as the 2-aryl substituent, were potential candidates for anti-cancer drugs.

Topics: Antineoplastic Agents; Cell Line, Tumor; Drug Screening Assays, Antitumor; Humans; Methyl Ethers; Naphthoquinones; Oximes; Structure-Activity Relationship

In order to clarify the biosynthetic origin of 2-geranyl-1,4-naphthoquinone and its biogenetically related anthraquinone, which are possible intermediates of anthrasesamones, [1-(13)C]glucose was administered to a hairy root culture of Sesamum indicum. The labeling patterns of these quinone derivatives indicated that the naphthoquinone ring and geranyl side-chain of geranylnaphthoquinone were respectively biosynthesized through the shikimate and methylerythritol phosphate pathways, and that these quinone derivatives have the same biosynthetic origin.

Topics: Anthraquinones; Carbon Isotopes; Molecular Structure; Naphthoquinones; Plant Roots; Prenylation; Sesamum; Tissue Culture Techniques

There are no reports describing the ability of pro-oxidants to protect against radiation-induced apoptosis. Activation of the redox-sensitive transcription factor Nrf2 by low levels of ROS is known to protect against oxidative stress-induced cell death. In this study, hydrogen peroxide, diethylmaleate, and 1,4-naphthoquinone (NQ) exhibited complete protection against radiation-induced cell death in lymphocytes as estimated by propidium iodide staining. Radioprotection by NQ was demonstrated by inhibition of caspase activation, decrease in cell size, DNA fragmentation, nuclear blebbing, and clonogenic assay. Interestingly, NQ offered protection to lymphocytes even when added to cells postirradiation. NQ increased intracellular ROS levels and decreased GSH levels. NQ activated Nrf2 and increased the expression of the cytoprotective gene heme oxygenase-1 in lymphocytes. NQ increased ERK phosphorylation, which is upstream of Nrf2, and this ERK activation was through increased intracellular calcium levels. Administration of NQ to mice offered protection against whole-body irradiation (WBI)-induced apoptosis in splenic lymphocytes and loss of viability of spleen and bone marrow cells. It restored WBI-mediated changes in hematological parameters and functional responses of lymphocytes. Importantly, NQ rescued mice against WBI-induced mortality. These results demonstrated that a pro-oxidant such as NQ can protect against radiation-induced apoptosis by activation of multiple prosurvival mechanisms including activation of the calcium-ERK1/2-Nrf2 pathway.

Topics: Animals; Apoptosis; Calcium Signaling; Cell Line; Enzyme Activation; Humans; Hydrogen Peroxide; Maleates; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Naphthoquinones; NF-E2-Related Factor 2; Oxidative Stress; Phosphorylation; Reactive Oxygen Species

The oxidative addition of anilines (2) with 1,4-naphthoquinone (3) to give N-aryl-2-amino-1,4-naphthoquinones (1) was found to be catalyzed by copper(II) acetate. In the absence of the catalyst, the reactions are slower and give lower yields with the formation of many colateral products. In the presence of 10 mol % hydrated copper(II) acetate, the reactions are generally more efficient in that they are cleaner, higher yielding, and faster.

Topics: Aniline Compounds; Catalysis; Molecular Structure; Naphthoquinones; Organometallic Compounds; Oxidation-Reduction; Stereoisomerism

We recently discovered that 5, 8-O-dimethyl acylshikonin derivatives displayed the selectivity towards MCF-7 and no toxicity to normal cells. Herein, a series of the corresponding 6-isomers of 5, 8-O-dimethyl acylshikonin derivatives were synthesized starting from shikonin. In vitro evidence of the cytotoxicities indicated that most of thecompounds were more active than or comparative to shikonin and retained the selectivity against MCF-7, MDA-MB-231 besides no toxicity in the normal cells. Also, in vivo anticancer activity of the positional isomers 5p, 6c further showed that 6-isomers of 5, 8-O-dimethyl acylshikonin derivatives were more active than their corresponding 2-isomers. Thus, we may conclude that the position of the side chain of shikonin attached to 5,8-dimethoxy -1,4-naphthoquinone is associated with the antitumor activity.

Topics: Acylation; Animals; Antineoplastic Agents; Cell Survival; Drug Screening Assays, Antitumor; Female; Fibroblasts; Humans; Inhibitory Concentration 50; Isomerism; Male; Mice; Naphthoquinones; Neoplasms; Structure-Activity Relationship; Tumor Cells, Cultured

Our work on targeting redox equilibria of malarial parasites propagating in red blood cells has led to the selection of six 1,4-naphthoquinones, which are active at nanomolar concentrations against the human pathogen Plasmodium falciparum in culture and against Plasmodium berghei in infected mice. With respect to safety, the compounds do not trigger hemolysis or other signs of toxicity in mice. Concerning the antimalarial mode of action, we propose that the lead benzyl naphthoquinones are initially oxidized at the benzylic chain to benzoyl naphthoquinones in a heme-catalyzed reaction within the digestive acidic vesicles of the parasite. The major putative benzoyl metabolites were then found to function as redox cyclers: (i) in their oxidized form, the benzoyl metabolites are reduced by NADPH in glutathione reductase-catalyzed reactions within the cytosols of infected red blood cells; (ii) in their reduced forms, these benzoyl metabolites can convert methemoglobin, the major nutrient of the parasite, to indigestible hemoglobin. Studies on a fluorinated suicide-substrate indicate as well that the glutathione reductase-catalyzed bioactivation of naphthoquinones is essential for the observed antimalarial activity. In conclusion, the antimalarial naphthoquinones are suggested to perturb the major redox equilibria of the targeted infected red blood cells, which might be removed by macrophages. This results in development arrest and death of the malaria parasite at the trophozoite stage.

Topics: Animals; Antimalarials; Biocatalysis; Dose-Response Relationship, Drug; Glutathione Reductase; Humans; Mice; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Parasitic Sensitivity Tests; Plasmodium berghei; Plasmodium falciparum; Structure-Activity Relationship

Mass spectrometry analysis of 2-(acylamino)-1,4-naphthoquinone derivatives was carried out using electrospray ionization ion source in combination with tandem mass spectrometry. Protonated molecules were dissociated by application of the collision-induced dissociation (CID), and the protonation sites were suggested on the basis of the HOMO, molecular electrostatic potential map (MEP), proton affinity, and Fukui functions calculated by B3LYP/6-31+G(d,p). The main fragmentation mechanisms undergone by the protonated ions were elucidated on the basis of energy, geometry, and topology analysis of equilibrium geometries. Compounds exhibiting only aliphatic hydrogens at the lateral chain undergo interesting ketene elimination. On the other hand, only the benzoylium ion formation is detected for 2-benzoylamino-1,4-naphthoquinone. The bonds geometric and atoms in molecules parameters give evidence that acidic hydrogen atoms play an important role in the fragmentation pathways.

Topics: Mass Spectrometry; Molecular Structure; Naphthoquinones; Quantum Theory

Previously, we reported that vitamin K₃ (menadione, 2-methyl-1,4-naphthoquinone) (compound 2) inhibits the activity of human mitochondrial DNA polymerase γ (pol γ). In this study, we investigated the inhibitory effects (IEs) of vitamin K3 and its derivatives, such as 1,4-naphthoquinone (compound 1) and 1,2-dimethyl-1,4-naphthoquinone (compound 3), on the activity of mammalian pols. Among compounds 1-3 (10 µM for each), compound 1 was the strongest inhibitor of mammalian pols α and λ, which belong to the B and X pol families, respectively, whereas compound 2 was the strongest inhibitor of human pol γ, a family A pol. However, these compounds did not affect the activity of human pol κ, a family Y pol. As we previously found a positive relationship between pol λ inhibition and anti-inflammatory action, we examined whether these vitamin K₃ derivatives are able to inhibit inflammatory responses. Among the three compounds tested, compound 1 caused the greatest reduction in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced acute inflammation in mouse ears. In addition, in a cell culture system using RAW264.7 mouse macrophages, compound 1 displayed the strongest suppression of tumor necrosis factor (TNF)-α production induced by lipopolysaccharide (LPS). In an in vivo mouse model of LPS-evoked acute inflammation, the intraperitoneal injection of compound 1 into mice suppressed TNF-α production in their peritoneal macrophages and serum. In an in vivo colitis mouse model induced using dextran sulfate sodium (DSS), the vitamin K₃ derivatives markedly suppressed DSS-evoked colitis. In conclusion, this study has identified several vitamin K₃ derivatives, such as compound 1, that are promising anti-inflammatory candidates.

Topics: Animals; Anti-Inflammatory Agents; Colitis; Dextran Sulfate; DNA-Directed DNA Polymerase; Enzyme Inhibitors; Female; Humans; Inflammation; Isoenzymes; Lipopolysaccharides; Macrophages, Peritoneal; Male; Mice; Mice, Inbred C57BL; Naphthoquinones; Nucleic Acid Synthesis Inhibitors; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha; Vitamin K 3

Ring the changes: the direct cross-coupling of electron-deficient 1,4-benzoquinone or its derivatives with electron-rich alkyl vinyl ethers proceeds in a tandem manner to produce substituted benzene rings with good selectivity and in good to excellent yields. The reaction has the potential for the rapid synthesis of diverse substituted benzene rings as it is not limited by substituent effects.

Topics: Alkenes; Catalysis; Molecular Structure; Naphthoquinones; Organometallic Compounds; Palladium

Oxidation of 2-methyl-1-naphthol (MNL) with molecular oxygen proceeds efficiently under mild reaction conditions (3 atm O(2), 60-80 °C) in the absence of any catalyst or sensitizer and produces 2-methyl-1,4-naphthoquinone (MNQ, menadione, or vitamin K(3)) with selectivity up to 80% in nonpolar solvents. (1)H NMR and (1)H,(1)H-COSY studies revealed the formation of 2-methyl-4-hydroperoxynaphthalene-1(4H)-one (HP) during the reaction course. Several mechanistic hypotheses, including conventional radical autoxidation, electron transfer mechanisms, photooxygenation, and thermal intersystem crossing (ISC), have been evaluated using spectroscopic, mass-spectrometric, spin-trapping, (18)O(2) labeling, kinetic, and computational techniques. Several facts collectively implicate that ISC contributes significantly into MNL oxidation with O(2) at elevated pressure: (i) the reaction rate is unaffected by light; (ii) C-C-coupling dimers are practically absent; (iii) the reaction is first order in both MNL and O(2); (iv) the observed activation parameters (ΔH(‡) = 8.1 kcal mol(-1) and ΔS(‡) = -50 eu) are similar to those found for the spin-forbidden oxidation of helianthrene with (3)O(2) (Seip, M.; Brauer, H.-D. J. Am. Chem. Soc.1992, 114, 4486); and (v) the external heavy atom effect (2-fold increase of the reaction rate in iodobenzene) points to spin inversion in the rate-limiting step.

Topics: Kinetics; Naphthols; Naphthoquinones; Oxidation-Reduction; Oxygen; Solvents; Spin Labels

Various oxygen containing 1,4-naphthoquinone derivatives have been synthesized chemoselectively by an economical, viable green methodology approach using water as solvent with or without surfactants such as Triton X-100, SDS, LD (laundry detergent), and TBAB, a phase transfer catalyst and evaluated for their in vitro antifungal and antibacterial activity. The antifungal profile of 3, 4a, 4b, and 6 indicated that compounds 3a, 3b, 4b, 6a, and 6c have potent antifungal activity compared to clinically prevalent antifungal drugs Fluconazole and Amphotericin-B against Sporothrix schenckii, Trichophyton mentagraphytes, and Candida parapsilosis and compound 3b has been found to be a lead antifungal agent for further study.

Topics: Antifungal Agents; Candida; Catalysis; Drug Evaluation, Preclinical; Micelles; Microbial Sensitivity Tests; Naphthoquinones; Oxygen; Sporothrix; Trichophyton; Water

An aqueous ethanol extract of Pyrola rotundifolia L. induced AMP-activated protein kinase (AMPK) phosphorylation in C2C12 myotubes. The bioassay-guided fractionation of the extract led to the isolation a 2-methyl-7-hydroxymethyl-1,4-naphthoquinone, or a 7'-hydroxy-chimaphilin, which showed concentration-dependent AMPK phosphorylation activity at 2.5-20 μg/ml. At a concentration of 10 μg/ml (50 μM), an approximately four-fold increase in the AMPKα(Thr¹⁷²) phosphorylation level was observed. The stimulatory effect of naphthoquinone on AMPK activity was comparable to that of known compounds found in natural sources that activate the AMPK signaling pathway.

Topics: AMP-Activated Protein Kinases; Animals; Cell Line; Dose-Response Relationship, Drug; Enzyme Activators; Mice; Molecular Structure; Muscle Fibers, Skeletal; Naphthoquinones; Phosphorylation; Plant Extracts; Pyrola

A method was developed for the quantification of 1-4 ring quinones in urine samples using liquid-liquid extraction followed by analysis with gas chromatography-mass spectrometry. Detection limits for the ten quinones analyzed are in the range 1-2 nmol dm(-3). The potential use of this approach to monitor urinary quinone levels was then evaluated in urine samples from both Sprague-Dawley rats and human subjects. Rats were exposed to 9,10-phenanthraquinone (PQ) by both injection and ingestion (mixed with solid food and dissolved in drinking water). Urinary levels of PQ were found to increase by up to a factor of ten compared to control samples, and the levels were found to depend on both the dose and duration of exposure. Samples were also collected and analyzed periodically from human subjects over the course of six months. Eight quinones were detected in the samples, with levels varying from below the detection limit up to 3 μmol dm(-3).

Topics: Adult; Animals; Biomarkers; Chrysenes; Environmental Exposure; Female; Gas Chromatography-Mass Spectrometry; Humans; Liquid-Liquid Extraction; Naphthoquinones; Phenanthrenes; Quinones; Rats; Rats, Sprague-Dawley

Monoamine oxidase (MAO) catalyzes the oxidative deamination of biogenic and exogenous amines and its inhibitors have therapeutic value for several conditions including affective disorders, stroke, neurodegenerative diseases and aging. The discovery of 2,3,6-trimethyl-1,4-naphthoquinone (TMN) as a nonselective and reversible inhibitor of MAO, has suggested 1,4-naphthoquinone (1,4-NQ) as a potential scaffold for designing new MAO inhibitors. Combining molecular modeling tools and biochemical assays we evaluate the kinetic and molecular details of the inhibition of human MAO by 1,4-NQ, comparing it with TMN and menadione. Menadione (2-methyl-1,4-naphthoquinone) is a multitarget drug that acts as a precursor of vitamin K and an inducer of mitochondrial permeability transition. Herein we show that MAO-B was inhibited competitively by 1,4-NQ (K(i)=1.4 μM) whereas MAO-A was inhibited by non-competitive mechanism (K(i)=7.7 μM). Contrasting with TMN and 1,4-NQ, menadione exhibited a 60-fold selectivity for MAO-B (K(i)=0.4 μM) in comparison with MAO-A (K(i)=26 μM), which makes it as selective as rasagiline. Fluorescence and molecular modeling data indicated that these inhibitors interact with the flavin moiety at the active site of the enzyme. Additionally, docking studies suggest the phenyl side groups of Tyr407 and Tyr444 (for MAO-A) or Tyr398 and Tyr435 (for MAO-B) play an important role in the interaction of the enzyme with 1,4-NQ scaffold through forces of dispersion as verified for menadione, TMN and 1,4-NQ. Taken together, our findings reveal the molecular details of MAO inhibition by 1,4-NQ scaffold and show for the first time that menadione acts as a competitive and reversible inhibitor of human MAO.

Topics: Animals; Humans; Kinetics; Models, Molecular; Monoamine Oxidase; Monoamine Oxidase Inhibitors; Naphthoquinones; Protein Binding; Vitamin K 3; Vitamins

The pentacyclic 1,4-naphthoquinones 1a-d were cytotoxic (IC(50) approximately 2-7 microM) to human leukemic cell lines K562 (oxidative stress-resistant), Lucena-1 (MDR phenotype) and Daudi. Fresh leukemic cells obtained from patients, some with the MDR phenotype, were also sensitive to these compounds. The pentacyclic 1,4-naphthoquinones 1a and 1c induced apoptotic cell death in cells from leukemic patients as determined by flow cytometry. Conversely, the cell lines were highly insensitive to lapachol (2) and alpha-lapachone (3). Mitomycin-C inhibited cell proliferation at concentrations as low as 0.5 microM. The low toxicity against lymphocytes activated by phytohemagglutinin shows that these compounds are selective for the cancer cells studied. Previous data suggest that these compounds (1a-d) can be bioactivated in situ by reduction followed by rearrangement leading to enones, which are powerful alkylating agents. In contrast, lapachol (2) and beta-lapachone (3), which cannot be bioactivated by reduction, showed little activity against the same cell lines.

Topics: Cell Death; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Leukemia; Leukocytes, Mononuclear; Mitomycin; Naphthoquinones

The most important mechanism of the beta-lactam antibiotic resistance is the destruction of the antibiotics by the enzyme beta-lactamase. Use of beta-lactamase inhibitors in combination with antibiotics is one of the successful antibacterial strategies. The inhibitory effect of a phytochemical, 1,4-naphthalenedione, isolated from the plant Holoptelea integrifolia on beta-lactamase is reported here. This compound was found to have a synergistic effect with the antibiotic amoxicillin against a resistant strain of Staphylococcus aureus. The enzyme was purified from the organism and incubated with the compound. An assay showed that the compound can inhibit the enzymatic activity of beta-lactamase. Modeling and molecular docking studies indicated that the compound can fit into the active site of beta-lactamase. Hence, the compound can serve as a potential lead compound for the development of effective beta-lactamase inhibitor that can be used against beta-lactam-resistant microbial strains.

Topics: Amoxicillin; beta-Lactamase Inhibitors; beta-Lactamases; Catalytic Domain; Enzyme Assays; Gas Chromatography-Mass Spectrometry; Hydrogen Bonding; Ligands; Naphthoquinones; Spectroscopy, Fourier Transform Infrared; Substrate Specificity; Ulmaceae

Four new n-butylamino and two sulfur-containing derivatives of polyfluoro-1,4-naphthoquinone were synthesized and their mutagenic and antioxidant properties in Salmonella cells, as well as the cytotoxicity in human myeloma (RPMI 8226), human mammary adenocarcinoma (MCF-7), mouse fibroblasts (LMTK) and primary mouse fibroblast cells (PMF) were studied. 2-n-Butylamino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (1) showed efficient inhibition of the growth of the tumor cells. 2,8-Di-(n-butyl-amino)-3,5,6,7-tetrafluoro-1,4-naphthoquinone (2) had significantly less growth-inhibiting properties, while 2,6-di-(n-butylamino)-3,5,7,8-tetrafluoro-1,4-naphthoquinone (3) and 2,6,8-tri-(n-butylamino)-3,5,7-tetrafluoro-1,4-naphthoquinone (4), demonstrated very low cytotoxicity. Compounds 1 and 2 were remarkably less cytotoxic while compound 3 and 4 were not cytotoxic toward LMTK and PMF cells as compared with tumor human cell lines. Cytotoxicity of 2-(2'-methylthioethyl)amino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (5) and (2,2'-dithiodi-2)-3,5,6,7,8-pentafluoro-1,4-naphthoquinone-2-ylamino)ethan (6) toward mammalian cells was compared with that for compounds 1 and 2.

Topics: Amines; Animals; Antineoplastic Agents; Antioxidants; Bacteria; Cell Line, Tumor; Fluorine; Humans; Inhibitory Concentration 50; Mice; Mutagenesis; Naphthoquinones; Sulfur

We report here a simple entry into naphtho[2,3-d]isoxazole-4,9-dione system containing a EWG in position 3 using the readily available 2,3-dichloro-1,4-naphthoquinone and nitromethyl derivatives in the presence of base. Antifungal activity of synthesised naphthoquinones was evaluated against ATCC and PYCC reference strains of Candida. The results suggest that the naphtho[2,3-d]isoxazole-4,9-dione scaffold has the potential to be developed into novel and safe therapeutic antifungal agents.

Topics: Antifungal Agents; Candida; Isoxazoles; Microbial Sensitivity Tests; Naphthoquinones

Twenty-six novel naphthoquinone aliphatic esters were synthesized by esterification of 1,4-naphthoquinone alcohols with various aliphatic acids. The 1,4-naphthoquinone alcohols were prepared from 1-hydroxy-2-naphthoic acid in nine steps with excellent yields. Twenty-four of the novel synthetic naphthoquinone esters showed significant antimalarial activity with IC(50) values in the range of 0.03-16.63 microM. The length of the aliphatic chain and the presence of C-2' substituents on the propyl chain affected the activity. Interestingly, compounds 31 and 37 showed very good antimalarial activity and were not toxic to normal Vero cells, and the PTI values of 31 (>1990.38) and 37 (1825.94) are excellent. Both 31 and 37 showed potent inhibition against P. falciparum 3D7 cyt bc(1) and no inhibition on rat cyt bc(1). They showed IC(50) values in the nanomolar range, providing full inhibition of cyt bc(1) with one molecule inhibitor bound per cyt bc(1) monomer at the Q(o) site.

Topics: Animals; Antimalarials; Antineoplastic Agents; Cell Survival; Chlorocebus aethiops; Electron Transport Complex III; Erythrocytes; Inhibitory Concentration 50; Malaria, Falciparum; Male; Mitochondrial Membranes; Naphthoquinones; Plasmodium falciparum; Rats; Rats, Wistar; Saccharomyces cerevisiae; Structure-Activity Relationship; Vero Cells

Quantum and molecular mechanics calculations for the Diels-Alder reactions of cyclopentadiene with 1,4-naphthoquinone, methyl vinyl ketone, and acrylonitrile have been carried out at the vacuum-water interface and in the gas phase. In conjunction with previous studies of these cycloadditions in dilute solution, a more complete picture of aqueous environmental effects emerges with implications for the origin of observed rate accelerations using heterogeneous aqueous suspensions, "on water" conditions. The pure TIP4P water slab maintains the bulk density and hydrogen-bonding properties in central water layers. The bulk region merges to vacuum over a ca. 5 A band with progressive diminution of the density and hydrogen bonding. The relative free energies of activation and transition structures for the reactions at the interface are found to be intermediate between those calculated in the gas phase and in bulk water; i.e., for the reaction with 1,4-naphthoquinone, the DeltaDeltaG(++) values relative to the gas phase are -3.6 and -7.3 kcal/mol at the interface and in bulk water, respectively. Thus, the results do not support the notion that a water surface is more effective than bulk water for catalysis of such pericyclic reactions. The trend is in qualitative agreement with expectations based on density considerations and estimates of experimental rate constants for the gas phase, a heterogeneous aqueous suspension, and a dilute aqueous solution for the reaction of cyclopentadiene with methyl vinyl ketone. Computed energy pair distributions reveal a uniform loss of 0.5-1.0 hydrogen bond for the reactants and transition states in progressing from bulk water to the vacuum-water interface. Orientational effects are apparent at the surface; e.g., the carbonyl group in the methyl vinyl ketone transition structure is preferentially oriented into the surface. Also, the transition structure for the 1,4-naphthoquinone case is buried more in the surface, and the free energy of activation for this reaction is most similar to the result in bulk water.

Topics: Acrylonitrile; Butanones; Cyclopentanes; Models, Chemical; Molecular Dynamics Simulation; Naphthoquinones; Quantum Theory; Surface Properties; Thermodynamics; Vacuum; Water

Selected biological effects of 1,4-naphthoquinone, menadione (2-methyl-1,4-naphthoquinone) and structurally related quinones from natural sources--the 5-hydroxy-naphthoquinones juglone, plumbagin and the 2-hydroxy-naphthoquinones lawsone and lapachol--were studied in human keratinocytes (HaCaT). 1,4-naphthoquinone and menadione as well as juglone and plumbagin were highly cytotoxic, strongly induced reactive oxygen species (ROS) formation and depleted cellular glutathione. Moreover, they induced oxidative DNA base damage and accumulation of DNA strand breaks, as demonstrated in an alkaline DNA unwinding assay. Neither lawsone nor lapachol (up to 100 microM) were active in any of these assays. Cytotoxic and oxidative action was paralleled by stimulation of stress signaling: all tested quinones except lawsone and lapachol strongly induced phosphorylation of the epidermal growth factor receptor (EGFR) and the related ErbB2 receptor tyrosine kinase. EGFR activation by plumbagin, juglone and menadione was attenuated by a superoxide dismutase mimetic, indicating that ROS-related mechanisms contribute to EGFR activation by these naphthoquinones.

Topics: Cell Line; Dose-Response Relationship, Drug; Humans; Keratinocytes; Naphthoquinones; Oxidative Stress; Reactive Oxygen Species; Signal Transduction

Ant colony optimization (ACO) is a meta-heuristic algorithm, which is derived from the observation of real ants. In this paper, ACO algorithm is proposed to feature selection in quantitative structure property relationship (QSPR) modeling and to predict lambda(max) of 1,4-naphthoquinone derivatives. Feature selection is the most important step in classification and regression systems. The performance of the proposed algorithm (ACO) is compared with that of a stepwise regression, genetic algorithm and simulated annealing methods. The average absolute relative deviation in this QSPR study using ACO, stepwise regression, genetic algorithm and simulated annealing using multiple linear regression method for calibration and prediction sets were 5.0%, 3.4% and 6.8%, 6.1% and 5.1%, 8.6% and 6.0%, 5.7%, respectively. It has been demonstrated that the ACO is a useful tool for feature selection with nice performance.

Topics: Algorithms; Animals; Ants; Linear Models; Models, Biological; Models, Molecular; Naphthoquinones; Quantitative Structure-Activity Relationship

Fluorinated derivatives of 1,4-naphthoquinone are highly potent inhibitors of Cdc25A and Cdc25 phosphatases and growth of tumor cells. Five new N-substituted polyfluorinated derivatives of 2-amino-1,4-naphthoquinone were synthesized and their mutagenic and antioxidant properties in Salmonella cells, as well as cytotoxicity in human myeloma (RPMI 8226), human mammary adenocarcinoma (MCF-7), mouse fibroblasts (LMTK) and primary mouse fibroblast cells (PMF) were studied. 2-tert-Butylamino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (1) inhibited the growth of normal control and tumor cells at the same concentration. Three compounds: 2-diethylamino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (2), 2-ethylamino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (3), 2-phenylamino-3,5,6,7,8-pentafluoro-1,4-naphthoquinone (4) exhibited a 50% decrease in the growth of cancer cells at low and comparable concentrations (2.4-8.6 microM) while being remarkably less cytotoxic toward normal LMTK and PMF cells. Quinones (1)-(4), but not 2-phenylamino-3-methyl-5,6,7,8-tetrafluoro-1,4-naphthoquinone (5), efficiently suppressed spontaneous mutagenesis in Salmonella cells, while all compounds 1-5 decreased the mutagenic effect of H2O2 on bacterial cells. Their possible perspectives as anticancer drugs are shortly discussed.

Topics: Amines; Animals; Antineoplastic Agents; Antioxidants; Cell Line, Tumor; Halogenation; Humans; Mice; Mutagenesis; Naphthoquinones; Salmonella typhimurium

2-chloro-3-(4-methylpiperazin-1-yl)naphthalene-1,4-dione (3a), 2-chloro-3-(pyrrolidin-1-yl)naphthalene-1,4-dione (3b), 2-chloro-3-(piperidin-1-yl)naphthalene-1,4-dione (3c), 2-chloro-3-morpholinonaphthalene-1,4-dione (3d), 2-chloro-3-(2-phenylhydrazinyl)naphthalene-1,4-dione (3e), 2-(allylamino)-3-chloronaphthalene-1,4-dione (3f), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetic acid (3g), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)succinic acid (3h), methyl 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetate (3i), 2-chloro-3-(2-mercaptoethylthio)naphthalene-1,4-dione (3j), 3-hydroxy-4-methyl-4H-naphtho[2,3-b][1,4]thiazine-5,10-dione (3k) and compounds 3l-q have been synthesized by a green methodology approach using water as solvent and evaluated for their antifungal and antibacterial activity. The antifungal profile of 3a-n indicated that compounds 3a-d, 3j, 3e and 3k have potent antifungal activity. Amongst the most promising antifungal compounds, 3a-g, 3j, 3k showed better antifungal activity than clinically prevalent antifungal drugs Fluconazole and Amphotericin-B against Trichophyton mentagraphytes and compounds 3j and 3k have been found to be lead antifungal bicyclic and tricyclic 1,4-naphthoquinones. Compound 3k also exhibited pronounced antibacterial activity.

Topics: Anti-Bacterial Agents; Antifungal Agents; Bacteria; Fungi; Green Chemistry Technology; Microbial Sensitivity Tests; Naphthoquinones; Nitrogen; Sulfur; Water

A system device using multifunctional conjugated copolymer poly(5-hydroxy-1,4-naphthoquinone-co-hydroxy-2-thioacetic acid-1,4-naphthoquinone) acting both as immobilizing and transducing element for reagentless immunosensor has been constructed. Its functionality was evaluated in an antigen-antibody interaction model using ovalbumin-anti-ovalbumin. It was shown that the system specifically detects via electrochemical signal the antigen-antibody immune interaction in a reagentless context. Comparison to the conventional ELISA technique relevant to performance and sensitivity was presented.

Topics: Acetic Acid; Biosensing Techniques; Electrochemistry; Enzymes, Immobilized; Naphthoquinones; Polymers; Reference Standards; Serum; Sulfhydryl Compounds; Time Factors

The aim of this study is to find out whether several 1,4-naphthoquinones (1,4-NQ) can interact with the amyloidogenic pathway of the amyloid precursor protein processing, particularly targeting at β-secretase (BACE), as well as at β-amyloid peptide (Aβ) aggregation and disaggregating preformed Aβ fibrils. Compounds bearing hydroxyl groups at the quinoid (2) or benzenoid rings (5, 6) as well as some 2- and 3-aryl derivatives (11-15) showed BACE inhibitory activity, without effect on amyloid aggregation or disaggregation. The halogenated compounds 8 and 10 were selective for the inhibition of amyloid aggregation. On the other hand, 1,4-naphthoquinone (1), 6-hydroxy-1,4-naphthoquinone (4) and 2-(3,4-dichlorophenyl)-1,4-naphthoquinone (26) did not show any BACE inhibitory activity but were active on amyloid aggregation and disaggregation preformed Aβ fibrils. Juglone (5-hydroxy-1,4-naphthoquinone (3), and 3-(p-hydroxyphenyl)-5-methoxy-1,4-napththoquinone (19) were active on all the three targets. Therefore, we suggest that 1,4-NQ derivatives, specially 3 and 19, should be explored as possible drug candidates or lead compounds for the development of drugs to prevent amyloid aggregation and neurotoxicity in Alzheimer's disease.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Amyloid Precursor Protein Secretases; Aspartic Acid Endopeptidases; Cell Line, Tumor; Humans; Naphthoquinones; Protease Inhibitors

Glycosylation of cell surfaces is a critical factor in many biological processes; however, the lack of effective analytical tools for the detection of cell surface carbohydrates has been the bottleneck for probing into the processes. In this paper, a novel electrochemical method is presented for the analysis of cell surface carbohydrates, which can be also used to detect the target cells. Firstly, 5-hydroxy-3-hexanedithiol-1,4-naphthoquinone (JUG(thio)), the electrochemical reporter, and anti-selectin aptamer are successively modified onto the surface of a gold electrode. Different concentrations of intestinal human colon adenocarcinoma (LS180) cells are employed as the target cells for this study. Consequently, the specific carbohydrates on the surfaces of LS180 cells and anti-selectin aptamers will compete for combination with selectin in the system. As a result, the oxidation signal of JUG(thio) is changed and the detection of the cell surface carbohydrates can be achieved easily and sensitively. Furthermore, the proposed method can be used to specifically detect LS180 cells in a wide concentration range, from 10(3) to 10(7) cells/mL, with a good linear relationship and low detection limit, which might be promising for the diagnosis of cancer and some other diseases in the future.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cell Line, Tumor; Electrochemical Techniques; Humans; L-Selectin; Naphthoquinones

(23E)-25-Methylcycloart-23-en-3β-ol (1), a cycloartane-type triterpenoid featuring an unusual skeleton of 31 carbon atoms, (17E)-cycloart-17,26-dien-3β-ol (2), a new cycloartane-type triterpenoid, and the other two new compounds 4R-hydroxy-4-(9S-hydroxy-12-methylhexan-6-yl)-3-methylcyclopent-2-enone (6) and 7-hydroxy-5-(2'-hydroxy-4',5'-dimethoxyphenyl)-2-methoxy-6-methyl-1,4-naphthoquinone (7), together with three known cycloart-3β-ol triterpenoids (3-5) were isolated from aerial parts of Aphanamixis grandifolia. Their structures were elucidated by spectroscopic analysis, and that of 1 was confirmed by single-crystal X-ray diffraction. The absolute configuration of two carbon stereocenters of compound 6 was determined to be 4R,9S by means of circular dichroism (CD) and auxiliary chiral α-methoxy-α-(trifluoromethyl)phenylacetic acid (MTPA) derivatives, respectively. The compound 3 exhibited significant cytotoxicities against HL-60, Hep G2 and HeLa, and compounds 1, 2, 5, 6 and 7 exhibited modest cytotoxicities. No activity of compound 4 could be due to the absence of the hydroxyl group at C-24.

Topics: Antineoplastic Agents, Phytogenic; Cell Survival; Circular Dichroism; Crystallography, X-Ray; Cyclopentanes; Humans; Magnetic Resonance Spectroscopy; Meliaceae; Models, Molecular; Naphthoquinones; Neoplasms; Triterpenes

Quinones have diverse pharmacological properties including antibacterial, antifungal, antiviral, anti-inflammatory, antipyretic and anticancer activity. The cytotoxic potential of 1,4-naphthoquinone (NQ14) was studied against B16F1 melanoma cells grown in vitro. NQ14 treatment resulted in a concentration-dependent cytotoxicity as indicated by MTT assay and lactate dehydrogenase leakage assay. Depletion in cellular glutathione levels after 1h incubation with NQ14 correlated with the corresponding increase in reactive oxygen species generation as determined by 2',7'-dicholorofluorescein diacetate assay suggests the role of oxidative stress in cell death. The frequency of micronucleated binucleate cells increased with increasing doses of NQ14 with a corresponding decrease in the cytokinesis block proliferation index indicating the drug induced genotoxicity and cell division delay. Further, a dose-dependent decrease in the clonogenic cell survival indicated the potential of NQ14 to inhibit cell proliferation contributing to cell death. The cell death after NQ14 treatment may be attributed to apoptosis as seen in DNA ladder pattern along with necrosis as indicated in flow cytometric analysis of Annexin V/PI stained cells. Results of the present study demonstrate the cytotoxic and genotoxic potential of NQ14 by the induction of oxidative stress mediated mechanisms leading to tumor cell kill.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Formazans; Glutathione; L-Lactate Dehydrogenase; Melanoma; Mice; Micronucleus Tests; Naphthoquinones; Necrosis; Oxidative Stress; Reactive Oxygen Species; Tetrazolium Salts

Angiogenesis inhibitors are beneficial for the prevention and treatment of angiogenesis-dependent diseases including cancer. Vitamin K2 and K3, which are naphthoquinone derivatives, inhibit angiogenesis. We examined the anti-cancer and anti-angiogenic effects of naphthoquinones and its structurally related compounds. Among these 13 compounds, 1,4-naphthoquinone strongly inhibited both human colon cancer cell (HCT116) growth and angiogenesis. To clarify the anti-angiogenic mechanism, the effects of 1,4-naphthoquinone on human umbilical vein endothelial cell (HUVEC) tube formation, proliferation and chemotaxis were examined. Consequently, 1,4-naphthoquinone inhibited HUVEC functions. These results suggest that 1,4-naphthoquinone may be useful to cancer therapy.

Topics: Animals; Antineoplastic Agents; Cell Division; Cell Line, Tumor; Chemotaxis; Colonic Neoplasms; Endothelium, Vascular; Femoral Artery; HeLa Cells; Humans; Male; Naphthoquinones; Neovascularization, Pathologic; Rats; Rats, Wistar; Umbilical Veins

A series of 2-Arylamino-3-chloro-1,4-naphthoquinones (3), 2-Amino-3-arylsulfanyl-1,4-naphthoquinones (5), 2-Arylamino-3-arylsulfanyl-1,4-naphthoquinones (6), Dihydrobenzo[f]naphtho[2,3-b][1,4]thiazepine-6,11-diones (9) (via Pictet-Spengler cyclization), Isoindoline-1,3-dione derivatives of 1,4-naphthoquinone (13), 2,2'-(1,4-Dioxo-1,4-dihydronaphthalene-2,3-diyl)bis(methylene)dibenzonitrile (14), 13-Amino-12-substituted-6H-benzo[e]naphtho [2,3-b][1,4]diazepine-6,11(12H)-diones (15-16), 2-Chloro-3-arylsulfanyl-1,4-naphthoquinones (17-18) and 3-Methyl-6H-benzo[b]phenothiazine-6,11(12H)-dione (19) were synthesized and studied for their antifungal and antibacterial activities. The results indicate that compounds 3b, 5a and 5b have potent antifungal activity. Amongst the most promising antifungal compounds, 3b showed better antifungal activity than clinically prevalent antifungal drug Fluconazole (MIC(50)=2.0 microg/mL) against Sporothrix schenckii (MIC(50)=1.56 microg/mL), significant profile against Candida albicans (MIC(50)=1.56 microg/mL), Cryptococcus neoformans (MIC(50)=0.78 microg/mL) and Trichophyton mentagraphytes (MIC(50)=1.56 microg/mL) and same antifungal activity when compared with Amphotericin-B against C. neoformans (MIC(50)=0.78 microg/mL). Compounds 3b, 5a and 5b also showed promising antibacterial activity.

Topics: Anti-Bacterial Agents; Antifungal Agents; Bacteria; Drug Design; Fungi; Microbial Sensitivity Tests; Naphthoquinones; Nitrogen; Sulfur

The introduction of Registration, Evaluation and Authorisation of Chemicals (REACH), requires companies to register and risk assess all substances produced or imported in volumes of >1 tonne per year. Extrapolation methods which use existing data for estimating the effects of chemicals are attractive to industry, and comparative data are therefore increasingly in demand. Data on natural toxic chemicals could be used for extrapolation methods such as read-across. To test this hypothesis, the toxicity of natural chemicals and their synthetic analogues were compared using standardised toxicity tests. Two chemical pairs: the napthoquinones, juglone (natural) and 1,4-naphthoquinone (synthetic); and anthraquinones, emodin (natural) and quinizarin (synthetic) were chosen, and their comparative effects on the survival and reproduction of collembolans, earthworms, enchytraeids and predatory mites were assessed. Differences in sensitivity between the species were observed with the predatory mite (Hypoaspis aculeifer) showing the least sensitivity. Within the chemical pairs, toxicity to lethal and sub-lethal endpoints was very similar for the four invertebrate species. The exception was earthworm reproduction, which showed differential sensitivity to the chemicals in both naphthoquinone and anthraquinone pairs. Differences in toxicity identified in the present study may be related to degree of exposure and/or subtle differences in the mode of toxic action for the chemicals and species tested. It may be possible to predict differences by identifying functional groups which infer increased or decreased toxicity in one or other chemical. The development of such techniques would enable the use of read-across from natural to synthetic chemicals for a wider group of compounds.

Topics: Animals; Anthraquinones; Ecotoxicology; Emodin; Naphthoquinones; Oligochaeta; Organic Chemicals; Reproduction; Risk Assessment; Soil

Lactococcus lactis is a gram-positive, normally homolactic fermenter that is known to produce several kinds of membrane associated quinones, which are able to mediate electron transfer to extracellular electron acceptors such as Fe(3+), Cu(2+) and hexacyanoferrate. Here we show that this bacterium is also capable of performing extracellular electron transfer to anodes by utilizing at least two soluble redox mediators, as suggested by the two-step catalytic current developed. One of these two mediators was herein suggested to be 2-amino-3-dicarboxy-1,4-naphthoquinone (ACNQ), via evaluation of standard redox potential, ability of the bacterium to exploit the quinone when exogenously provided, as well as by high performance liquid chromatography coupled with UV spectrum analysis. During electricity generation, L. lactis slightly deviated from its normal homolactic metabolism by excreting acetate and pyruvate in stoichiometric amounts with respect to the electrical current. In this metabolism, the anode takes on the role of electron sink for acetogenic fermentation. The finding that L. lactis self-catalyses anodic electron transfer by excretion of redox mediators is remarkable as the mechanisms of extracellular electron transfer by pure cultures of gram-positive bacteria had previously never been elucidated.

Topics: Benzoquinones; Biocatalysis; Bioelectric Energy Sources; Electric Conductivity; Electricity; Electrochemistry; Electrodes; Fermentation; Glucose; Lactococcus lactis; Naphthoquinones; Oxidation-Reduction; Solubility

1,4-naphthoquinone derivatives (NQD) containing lipophilic alkyl chains, i.e. 2-((Z)-heptadec-8-enyl)-3-methyl 1,4-naphthoquinone (QMe), 2-((Z)-heptadec-8-enyl)-3-hydroxy-1,4-naphthoquinone (QOH) and (Z)-octadec-9-enyl 1,4-naphthoquinone-2-carboxylate (QE) were synthesized. The redox behavior of these NQD was studied in ethanol and entrapped in the reversed bicontinuous cubic phase of space group type Pn3m (Q(224)) of aqueous monoolein. In ethanol, cyclic voltammetry curves exhibit two pairs of oxidation-reduction peaks arising from the redox processes controlled by adsorption and molecular diffusion. The NQD molecules are also electrochemically active in the cubic phase, indicating the participation in the 2e(-), 2H(+)-redox cycle at pH<9. Therefore, it was concluded that the head group of the entrapped NQD reaches the lipid bilayer interface of cubic phase during the process.

Topics: Electrochemistry; Glycerides; Liquid Crystals; Naphthoquinones; Oxidation-Reduction; Water; X-Ray Diffraction

The catalytic effects of different quinoid redox mediators (RM) on the simultaneous removal of sulphide and p-cresol in a denitrifying process were evaluated in batch studies. 2-Hydroxy-1,4-naphthoquinone (LAW) and anthraquinone-2,6-disulphonate (AQDS) did not significantly affect the sulphide oxidation rate, which, in contrast, was increased 14% in the presence of 1,2-naphthoquinone-4-sulphonate (NQS). The input of NQS on the oxidation of sulphide was also favourably reflected in a 13% higher sulphate production. All RM promoted a higher (up to 34% compared to the control lacking RM) degree of mineralization of p-cresol. LAW also supported a 47% higher denitrifying yield (Y(N2)), compared to the control lacking quinones. Nevertheless, AQDS and NQS decreased the Y(N2) by 12-13%. Our results suggest that a proper scrutiny should be conducted before deciding the sort of quinone to be applied in denitrifying processes. The heterogeneous effects observed also advise to consider both the respiratory rates and the yields as important parameters for deciphering the impact of RM on denitrifying processes.

Topics: Anaerobiosis; Anthraquinones; Cresols; Kinetics; Naphthoquinones; Nitrates; Oxidation-Reduction; Oxygen Consumption; Quinones; Sewage; Sulfates; Sulfides; Sulfonic Acids; Water Purification

Vascular smooth muscle cell (VSMCs) proliferation is an essential factor in cardiovascular diseases, such as primary atherosclerosis and in-stent restenosis. In this study, we examined the effects of the novel synthetic naphthoquinone, 2-pyrrilidino-3-(p-hydroxyphenylamino)-1,4-naphthoquinone (TW-96), on cultured VSMCs and endothelial cells (ECs). Pharmacological concentrations of the derivative TW96 were found to induce VSMCs death, probably by increasing ROS levels while decreasing mitochondrial potential (DeltaPsi(m)) without affecting ECs. Treatment of tissue cultures with ROS is known to induce MAPK activity. Our observations showed prolonged phosphorylation and perinuclear accumulation of ERK1/2 and p38 simultaneously with an inhibition of MKP1. Increased expression of Bax found in TW96-stimulated VSMCs was inhibited by the NADPH oxidase inhibitor diphenyliodonium (DPI). An examination of the suppressive effects of TW96 on PDGF-BB-stimulated VSMCs cycle progression showed that TW96 leads to migration arrest at concentrations lower than LC(50). We hope that this prototype derivative will establish the basis for creating more specific naphthoquinone derivatives aimed at preventing the VSMCs proliferation associated with stenosis and restenosis.

Topics: Animals; Cell Death; Cell Movement; Cell Survival; Cells, Cultured; Endothelium, Vascular; Muscle, Smooth, Vascular; Naphthoquinones; Rats

The NHC-catalyzed conjugate hydroacylation of 1,4-naphthoquinones allows for the synthesis of monoacylated 1,4-dihydroxynaphthalene derivatives. These targets, difficult to prepare selectively by standard protocols, represent important intermediates in the elaboration of highly substituted 1,4-naphthoquinone derivatives, which constitute relevant pharmaceutical scaffolds. High regioselectivity has been observed in the hydroacylation reaction when starting from nonsymmetrical quinones.

Topics: Acylation; Aldehydes; Catalysis; Heterocyclic Compounds; Hydroquinones; Methane; Molecular Structure; Naphthoquinones

Photoprocesses of 1,4-naphthoquinone (NQ) and its photoreactions with lysozyme in acetonitrile/water (3:1, v/v) solution were studied using 355 nm laser flash photolysis technique combined with electrophoresis and turbidimetric assay. The transient spectra of NQ were observed and the transient species were assigned. The electron transfer process from N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) to NQ triplet state ((3)NQ) was investigated and the rate constant was determined to be k(t1)=2.0 x 10(10)M(-1)s(-1). It has been found that (3)NQ can abstract hydrogen atom from lysozyme with a rate constant of k(t2)=2.4 x10(10)M(-1)s(-1). Furthermore, the results of steady-state analysis suggested that lysozyme can be damaged by NQ irradiated with UVA light influenced by the concentration of NQ and the gas saturated in the solution. The mechanisms of photosensitized damage of lysozyme were discussed.

Topics: Acetonitriles; Kinetics; Lasers; Muramidase; Naphthoquinones; Photolysis; Photosensitivity Disorders; Tetramethylphenylenediamine; Water

In animal models, naphthalene toxicity has been studied in different target organs and has been shown to be gender-dependent and metabolism related. In humans, it is readily absorbed and is metabolised by several cytochrome P450's. Naphthalene and its metabolites can cross the placental barrier and consequently may affect foetal tissues. The aim of this study was to compare the in vitro toxicity of naphthalene and its metabolites, 1-naphthol, 2-naphthol and 1,4-naphthoquinone, on human haematopoietic foetal progenitors (CFU-GM) derived from newborn male and female donors. The mRNA expression of Cyp1A2 and Cyp3A4 was also evaluated. Naphthalene did not affect CFU-GM proliferation, while 1-naphthol, 2-naphthol and particularly 1,4-naphthoquinone strongly inhibited the clonogenicity of progenitors, from both male and female donors. mRNA of Cyp1A2 and Cyp3A4 was not expressed neither at the basal level, nor after naphthalene treatment, while treatment with 1,4-naphthoquinone induced expression of both enzymes in both genders, with Cyp1A2 being expressed four times more than Cyp3A4. Female CFU-GM was significantly more sensitive to 1,4-naphthoquinone than male and after treatment both enzymes were expressed twice as much as in the male precursors. These results suggest that a gender-specific 1,4-naphthoquinone metabolic pathway may exist, which gives rise to unknown toxic metabolites.

Topics: Cell Proliferation; Colony-Forming Units Assay; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP3A; Female; Fetal Blood; Gene Expression Regulation, Enzymologic; Hematopoietic Stem Cells; Humans; Infant, Newborn; Male; Naphthalenes; Naphthols; Naphthoquinones; RNA, Messenger; Sex Factors

Three cytosolic NADPH-dependent flavin-associated proteins (Gox2107, Gox0502, and Gox2684) from Gluconobacter oxydans 621H were overproduced in Escherichia coli, and the recombinant enzymes were purified and characterized. Apparent native molecular masses of 65.2, 78.2, and 78.4 kDa were observed for Gox2107, Gox0502, and Gox2684, corresponding to a trimeric structure for Gox2107 and dimers for Gox0502 and Gox2684. Analysis of flavin content revealed Gox2107 was flavin adenine dinucleotide dependent, whereas Gox0502 and Gox2684 contained flavin mononucleotide. The enzymes were able to reduce vinyl ketones and quinones, reducing the olefinic bond of vinyl ketones as shown by (1)H nuclear magnetic resonance. Additionally, Gox0502 and Gox2684 stereospecifically reduced 5S-(+)-carvone to 2R,5S-dihydrocarvone. All enzymes displayed highest activities with 3-butene-2-one and 1,4-naphthoquinone. Gox0502 and Gox2684 displayed a broader substrate spectrum also reducing short-chain alpha-diketones, whereas Gox2107 was most catalytically efficient.

Topics: Bacterial Proteins; Butanones; Cloning, Molecular; Cyclohexane Monoterpenes; Dimerization; Escherichia coli; Flavin Mononucleotide; Flavin-Adenine Dinucleotide; Gene Expression; Gluconobacter oxydans; Ketones; Magnetic Resonance Spectroscopy; Molecular Weight; Monoterpenes; Naphthoquinones; Quinones; Recombinant Proteins; Substrate Specificity; Vinyl Compounds

Various aza-analogues of 1,4-naphthoquinone and menadione were prepared and tested as inhibitors and substrates of the plasmodial thioredoxin and glutathione reductases as well as the human glutathione reductase. The replacement of one to two carbons at the phenyl ring of the 1,4-naphthoquinone core by one to two nitrogen atoms led to an increased oxidant character of the molecules in accordance with both the redox potential values and the substrate efficiencies. Compared to the 1,4-naphthoquinone and menadione, the quinoline-5,8-dione 1 and both quinoxaline-5,8-diones 5 and 6 behaved as the most efficient subversive substrates of the three NADPH-dependent disulfide reductases tested. Modulation of these parameters was observed by alkylation of the aza-naphthoquinone core.

Topics: Animals; Aza Compounds; Drug Evaluation, Preclinical; Electrochemistry; Erythrocytes; Glutathione Reductase; Humans; Molecular Structure; Naphthoquinones; Plasmodium falciparum; Structure-Activity Relationship; Thioredoxins

An exposure chamber is described for the quantifiable addition of fine and ultrafine aerosol particulate matter directly to cells and used to demonstrate the in vitro cytotoxicity of fine 1,4-naphthoquinone particles to murine lung epithelial cells. The electrostatic particulate dosage and exposure system (EPDExS) operates on the principle of electrostatic precipitation and is shown to deposit fine and ultrafine aerosol particles directly to cells with 100% efficiency for particle diameters in the range of 40-530nm. This range is not limited by the EPDExS, but rather by the aerosolization method used for this study. Numbers of particles deposited onto the cells are counted with a condensation particle counter, negating any need to calculate or estimate particle exposure. The process of particle introduction, assessed using Trypan blue dye exclusion, had no effect on cell viability. In combination with a differential mobility classifier, the EPDExS can deliver select particle diameters to cells. The ability to control the diameter and number of particles deposited permits in vitro toxicity studies of particulate matter using different particle dosage metrics, i.e., particle number and size, surface area and mass. Finally, because EPDExS introduces particles directly from the aerosol, it can be used to expose cells grown at air/liquid interfaces.

Topics: Aerosols; Animals; Cell Survival; Chemical Precipitation; Epithelial Cells; Mice; Naphthoquinones; Particle Size; Particulate Matter; Pulmonary Alveoli; Static Electricity; Surface Properties

The pH effect on the one-electron photooxidation of 5-methyl-2'-deoxycytidine (d(m)C) by sensitization with 1,4-naphthoquinone (NQ) was investigated. Upon photoirradiation of d(m)C in the presence of NQ under slightly acidic conditions such as pH 5.0, 5-formyl-2'- deoxycytidine (d(f)C) was formed efficiently, whereas similar NQ-photosensitized oxidation of d(m)C proceeded to lesser extent under neutral or basic conditions. Under slightly acidic conditions, dmC radical cation favors to undergo irreversible deprotonation at the C(5)-methyl group to form a methyl-centered radical, leading to a higher yield of the alkali-labile oxidation products including d(f)C. In contrast, the d(m)C radical cation competitively undergoes deprotonation at the exocyclic N(4)-amino group under neutral or basic conditions, resulting in a decreased yield of NQ-photosensitized oxidation products.

Topics: Deoxycytidine; Electrons; Hydrogen-Ion Concentration; Naphthoquinones; Oxidation-Reduction; Photosensitizing Agents

In this work we studied the reaction of four quinones, 1,4-benzoquinone (1,4-BQ), 2,5-dimethyl-1,4-benzoquinone (2,5-DM-1,4-BQ), tetrachloro-1,4-benzoquinone (TC-1,4-BQ) and 1,4-naphthoquinone (1,4-NQ) with jack bean urease in phosphate buffer, pH 7.8. The enzyme was allowed to react with different concentrations of the quinones during different incubation times in aerobic conditions. Upon incubation the samples had their residual activities assayed and their thiol content titrated. The titration carried out with use of 5,5'-di-thiobis(2-nitrobenzoic) acid was done to examine the involvement of urease thiol groups in the quinone-induced inhibition. The quinones under investigation showed two distinct patterns of behaviour, one by 1,4-BQ, 2,5-DM-1,4-BQ and TC-1,4-BQ, and the other by 1,4-NQ. The former consisted of a concentration-dependent inactivation of urease where the enzyme-inhibitor equilibrium was achieved in no longer than 10min, and of the residual activity of the enzyme being linearly correlated with the number of modified thiols in urease. We concluded that arylation of the thiols in urease by these quinones resulting in conformational changes in the enzyme molecule is responsible for the inhibition. The other pattern of behaviour observed for 1,4-NQ consisted of time- and concentration-dependent inactivation of urease with a nonlinear residual activity-modified thiols dependence. This suggests that in 1,4-NQ inhibition, in addition to the arylation of thiols, operative are other reactions, most likely oxidations of thiols provoked by 1,4-NQ-catalyzed redox cycling. In terms of the inhibitory strength, the quinones studied formed a series: 1,4-NQ approximately 2,5-DM-1,4-BQ<1,4-BQ

Topics: Benzoquinones; Chloranil; Cyclohexenes; Enzyme Activation; Molecular Structure; Naphthoquinones; Protein Conformation; Structure-Activity Relationship; Sulfhydryl Compounds; Time Factors; Urease

The effects of oxygen in the photoreduction of 1,4-benzoquinone (BQ), 1,4-naphthoquinone (NQ), and a series of derivatives were studied in aqueous solution in the presence of acetonitrile and formate, aliphatic amines, e.g., EDTA or triethylamine, ascorbic acid, and alcohols, e.g., methanol or 2-propanol. The quinone triplet state is quenched, whereby the semiquinone and donor radicals are formed which react subsequently with oxygen. The overall reaction is oxidation of the donors and conversion of oxygen via the hydroperoxyl/superoxide radical into hydrogen peroxide. The quantum yield (Phi-O2) of this oxygen uptake changes in 2-propanol-water (1:10) from <0.01 for BQ to Phi-O2 = 0.5-0.8 for NQ. Generally Phi-O2 increases with increasing donor concentration. The specific properties of quinone structure, the radical equilibria and reactivity, and the concentration dependences are discussed.

Topics: 1-Propanol; Alcohols; Amines; Ascorbic Acid; Benzoquinones; Chemistry, Physical; Electrons; Formates; Hydrogen Peroxide; Models, Chemical; Naphthoquinones; Oxygen; Quinones; Time Factors; Water

In their inhibition-inducing interactions with enzymes, quinones primarily utilize two mechanisms, arylation and oxidation of enzyme thiol groups. In this work, we investigated the interactions of 1,4-naphthoquinone with urease in an effort to estimate the contribution of the two mechanisms in the enzyme inhibition. Jack bean urease, a homohexamer, contains 15 thiols per enzyme subunit, six accessible under non-denaturing conditions, of which Cys592 proximal to the active site indirectly participates in the enzyme catalysis. Unlike by 1,4-benzoquinone, a thiol arylator, the inactivation of urease by 1,4-naphthoquinone under aerobic conditions was found to be biphasic, time- and concentration-dependent with a non-linear residual activity-modified thiols dependence. DTT protection studies and thiol titration with DTNB suggest that thiols are the sites of enzyme interactions with the quinone. The inactivated enzyme had approximately 40% of its activity restored by excess DTT supporting the presence of sulfenic acid resulting from the oxidation of enzyme thiols by ROS. Furthermore, the aerobic inactivation was prevented in approximately 30% by catalase, proving the involvement of hydrogen peroxide in the process. When H2O2 was directly applied to urease, the enzyme showed susceptibility to this inactivation in a time- and concentration-dependent manner with the inhibition constant of H2O2 Ki = 3.24 mM. Additionally, anaerobic inactivation of urease was performed and was found to be weaker than aerobic. The results obtained are consistent with a double mode of 1,4-naphthoquinone inhibitory action on urease, namely through the arylation of the enzyme thiol groups and ROS generation, notably H2O2, resulting in the oxidation of the groups.

Topics: Enzyme Activation; Enzyme Inhibitors; Naphthoquinones; Oxidation-Reduction; Sulfhydryl Compounds; Urease

A series of 1,4-naphthoquinone derivatives diversely substituted at C-2, C-3, C-5 and C-8, prepared by reaction of amines, amino acids and alcohols with commercial 1,4-naphthoquinones, has been evaluated against papain and bovine spleen cathepsin B. These 1,4-naphthoquinone derivatives were found to be irreversible inhibitors for both cysteine proteases, with second-order rate constants, k(2), ranging from 0.67 to 35.4M(-1)s(-1) for papain, and from 0.54 to 8.03M(-1)s(-1) for cathepsin B. Some derivatives display a hyperbolic dependence of the first-order inactivation rate constant, k(obs), with the inhibitor concentration, indicative of a specific interaction process between enzyme and inhibitor. The chemical reactivity of the compounds towards cysteine as a model thiol is dependent on the naphthoquinone LUMO energy, whereas papain inactivation is not. The 1,4-naphthoquinone derivatives are inactive against the serine protease, porcine pancreatic elastase.

Topics: Cathepsin B; Cysteine; Cysteine Proteinase Inhibitors; Models, Molecular; Molecular Structure; Naphthoquinones; Pancreatic Elastase; Papain

The photoreduction of 1,4-benzoquinone, 1,4-naphthoquinone, 9,10-anthraquinone (AQ) and several methylated or halogenated derivatives in argon-saturated acetonitrile-water mixtures by indole, N-acetyltryptophan and N-acetyltyrosine was studied by time-resolved UV-vis spectroscopy using 20 ns UV laser pulses. The quinone triplet state is quenched by the aromatic amino acids and the rate constants are (1-5)x10(9)M(-1)s(-1). The semiquinone radical anion Q.(-) is the major observable transient after electron transfer from amino acids to the quinone triplet state. Termination of Q.(-) and amino acid derived radicals takes place in the mus-ms range. The effects of structure and other specific properties of quinones and amino acids are discussed. The radicals are subjects of intercept with oxygen, whereby hydrogen peroxide is eventually formed. The quantum yield of oxygen uptake Phi(-O2) as a measure of formation of hydrogen peroxide increases with increasing amino acid concentration, approaching Phi(-O2) for AQ in air-saturated solution.

Topics: Amino Acids, Aromatic; Anthraquinones; Benzoquinones; Electron Transport; Free Radicals; Halogens; Hydrogen Peroxide; Indoles; Kinetics; Methylation; Naphthoquinones; Oxidation-Reduction; Oxygen; Quinones; Spectrum Analysis; Tryptophan; Tyrosine; Ultraviolet Rays

5-(ethylen-2-yl)-1,4-naphthoquinone () is a photoremovable protecting group that absorbs up to 405 nm and provides fast and efficient release of bromide or diethyl phosphate. A convenient synthetic protocol to three derivatives of is described and their photochemistry in aqueous and acetonitrile solutions is investigated. The photoenol intermediates that expel the protected substrates were detected by laser flash photolysis and step-scan FTIR spectroscopy. The nucleofugacity of the leaving group and pH are the major factors that determine the reaction pathway.

Topics: Magnetic Resonance Spectroscopy; Naphthoquinones; Quantum Theory; Spectrometry, Mass, Fast Atom Bombardment; Spectroscopy, Fourier Transform Infrared

The polycyclic aromatic hydrocarbon naphthalene is an environmental pollutant, a component of jet fuel, and, since 2000, has been reclassified as a potential human carcinogen. Few studies of the in vitro human metabolism of naphthalene are available, and these focus primarily on lung metabolism. The current studies were performed to characterize naphthalene metabolism by human cytochromes P450. Naphthalene metabolites from pooled human liver microsomes (pHLMs) were trans-1,2-dihydro-1,2-naphthalenediol (dihydrodiol), 1-naphthol, and 2-naphthol. Metabolite production generated Km values of 23, 40, and 116 microM And Vmax values of 2860, 268, and 22 pmol/mg protein/min, respectively. P450 isoform screening of naphthalene metabolism identified CYP1A2 as the most efficient isoform for producing dihydrodiol and 1-naphthol, and CYP3A4 as the most effective for 2-naphthol production. Metabolism of the primary metabolites of naphthalene was also studied to identify secondary metabolites. Whereas 2-naphthol was readily metabolized by pHLMs to produce 2,6- and 1,7-dihydroxynaphthalene, dihydrodiol and 1-naphthol were inefficient substrates for pHLMs. A series of human p450 isoforms was used to further explore the metabolism of dihydrodiol and 1-naphthol. 1,4-Naphthoquinone and four minor unknown metabolites from 1-naphthol were observed, and CYP1A2 and 2D6*1 were identified as the most active isoforms for the production of 1,4-naphthoquinone. Dihydrodiol was metabolized by P450 isoforms to three minor unidentified metabolites with CYP3A4 and CYP2A6 having the greatest activity toward this substrate. The metabolism of dihydrodiol by P450 isoforms was lower than that of 1-naphthol. These studies identify primary and secondary metabolites of naphthalene produced by pHLMs and P450 isoforms.

Topics: Cytochrome P-450 Enzyme System; Humans; Isoenzymes; Kinetics; Microsomes, Liver; Molecular Structure; Naphthalenes; Naphthoquinones

The aquatic hyphomycete Heliscus lugdunensis belongs to a group of exclusively aquatic mitosporic fungi with an only scarcely explored potential to oxidatively attack xenobiotic compounds, and was used to study the biotransformation of the environmental pollutant metabolite 1-naphthol. H. lugdunensis metabolized approximately 74% of 1-naphthol within 5 days. The identification and quantification of degradation products using gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and high performance liquid chromatography revealed that approximately 12% of the parent compound was converted into 1-naphthylsulfate, 3% was transformed into 1-methoxy-naphthalene, and less than 1% was converted into 1,4-naphthoquinone. A further metabolite, most likely 4-hydroxy-1-naphthylsulfate, was also detected. In contrast to sulfate conjugate metabolites, no glucuronide and glucoside conjugates of 1-naphthol were found, and neither UDP-glucuronyltransferase nor UDP-glucosyltransferase present in H. lugdunensis showed activity towards 1-naphthol. These results support a role of fungi adapted to aquatic environments in affecting the environmental fate of pollutants in aquatic ecosystems.

Topics: Biotransformation; Glucuronosyltransferase; Hypocreales; Naphthalenes; Naphthols; Naphthoquinones; Sulfuric Acid Esters; Water Microbiology

Novel 2-hydroxy-3-nitro-1,4-naphthoquinones were synthesized by an improved method utilizing nitronium tetrafluoroborate in high yields. A subsequent conversion to 2-chloro-3-nitro-1,4-naphthoquinones and a substitution of the chlorine by hydroxyquinone anions yielded 3-nitro-2,2'-binaphthoquinones with a complete regiocontrol.

Topics: Hydroxylation; Molecular Structure; Naphthoquinones; Nitrogen; Stereoisomerism

The biological activity of 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) on Staphylococcus aureus was investigated in comparison with the unsubstituted 1,4-naphthoquinone (NQ). Complete inhibition of microbial growth was observed with ANQ and NQ at 50 and 10 microg/mL, respectively. The antibacterial effect of naphthoquinones decreased in the presence of sodium ascorbate, but the superoxide scavenger 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron) was able to protect S. aureus only from the harmful effect of ANQ. Naphthoquinones blocked oxygen uptake and induced cyanide-insensitive oxygen consumption. When combining rotenone or salicylhydroxamic acid with ANQ or NQ, a slight decrease in respiratory activity was observed. Assays in the presence of naphthoquinones induced an increase of lipid peroxidation in S. aureus, as determined by thiobarbituric acid reactive substances. These results showed that 1,4-naphthoquinones effectively act as electron acceptors and induce an increase in reactive oxygen species that are toxic to S. aureus cells.

Topics: Anti-Bacterial Agents; Lipid Peroxidation; Naphthoquinones; Oxidative Stress; Oxygen Consumption; Reactive Oxygen Species; Staphylococcus aureus

The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquinone (2HNQ), 5-hydroxy-1,4-naphthoquinone (5HNQ), and 5,8-dihydroxy-1,4-naphthoquinone (DHNQ), have been optimized using the semiempirical and ab initio theoretical methods. Semiempirical methods used for the optimization are Austin Model 1 (AM1) and Zerner's Intermediate Neglect of Differential Overlap/1(ZINDO/1). For ab initio calculations the 6-31G* basis set is used. The electronic spectra of 1,4-naphthoquinone and its hydroxy derivatives are calculated using the semiempirical Zerner's Intermediate Neglect of Differential Overlap/Spectroscopy (ZINDO/S) method employing the geometries optimized at AM1, ZINDO/1 and ab initio levels and compared with their electronic absorption spectra measured by us. For hydroxy substituted systems, such calculations for spectral assignments are made for the first time. It is found that though the predictions of the three theoretical methods for the geometries are similar, the predictions of the ZINDO/S method using the ZINDO/1 optimized geometries, are better for the transition wavelengths in the visible region of the hydroxy substituted naphthoquinones, especially for 5HNQ and DHNQ.

Topics: Cyclohexanes; Electrons; Hydrogen Bonding; Models, Molecular; Models, Theoretical; Molecular Conformation; Molecular Structure; Naphthoquinones; Software; Spectrophotometry; Ultraviolet Rays; X-Ray Diffraction

The PROPHIS facility is an efficient tool for the synthesis of chemicals with moderately concentrated sunlight on a semi-technical scale. The feasibility of selected solar photochemical reaction classes--including heterogeneous and homogeneous reactions--has been demonstrated using various set-ups of the plant. This paper outlines the potential of solar photochemistry by representative examples.

Topics: Acyclic Monoterpenes; Facility Design and Construction; Feasibility Studies; Monoterpenes; Naphthoquinones; Photochemistry; Pyridines; Sensitivity and Specificity; Stilbenes; Sunlight

A series of 1,4-naphthoquinone derivatives were synthesized and evaluated for antibacterial and antiviral activities. The structure-activity relationships of these compounds were also studied. The results suggest that compounds 9-22 showed in vitro marked antibacterial activity. Compounds 4c and 7a showed inhibitory effect against RNA dependent RNA polymerase induced poliovirus type 2 infected HeLa cells.

Topics: Anti-Bacterial Agents; Antiviral Agents; HeLa Cells; Humans; Microbial Sensitivity Tests; Molecular Structure; Naphthoquinones; Poliovirus; RNA-Dependent RNA Polymerase; Structure-Activity Relationship

A series of (S)-N-(1,4-naphthoquinon-2-yl)-alpha-amino acid methyl esters 3-9, 2-N,N-dialkylamino-1,4-naphthoquinones 10-11 and 2-hydroxy-3-(2'-mercaptoimidazolyl)-1,4-naphthoquinones and their cyclic analogs 12-15 were synthesized and evaluated for antifungal and antibacterial activities. The structure-activity relationships of these compounds were studied and the results show that the compounds 9b and 13c exhibited in vitro antifungal activity against Candida albicans, Cryptococcus neoformans, and Sporothrix schenckii, whereas compound 6a showed in vitro antibacterial activity against Streptococcus faecalis, K. pneumoniae, Escherichia coli, and Staphylococcus aureus.

Topics: Amino Acids; Anti-Bacterial Agents; Antifungal Agents; Bacteria; Fungi; Methyl Ethers; Molecular Structure; Naphthoquinones

The enthalpy of solution (Delta(solv)H(m)) and solubility of 1,4-naphthoquinone in CO(2) + n-pentane were measured at 308.15 K in the critical region of the binary fluid. In order to study the effect of phase behavior of the mixed solvent on Delta(solv)H(m), the experiments were carried out in the supercritical (SC) and subcritical region of the binary solvent. The density of the mixed solvent in different conditions was determined. The isothermal compressibility (K(T)) of the mixed solvent, and the partial molar volume (V(n-pentane)) of n-pentane in the solution were calculated. It was demonstrated that the Delta(solv)H(m) was negative in all conditions. Delta(solv)H(m) is nearly independent of pressure or density in all the solvents in a high-density region, in which compressibility of the solvent is very small; this indicates that the intermolecular interaction between the solvent and the solute is similar to that for liquid solutions. It is very interesting that Delta(solv)H(m) in the mixed SC fluid differs from the Delta(solv)H(m) in mixed subcritical fluids. The absolute value of Delta(solv)H(m) in the mixed SC fluid is close to that in pure SC CO(2) in the high-density region, and is much lower than that in pure SC CO(2) in the low-density region. In the mixed subcritical fluids, the Delta(solv)H(m) is also close to that in the pure CO(2) in the high-density region. However, at the same density, the absolute value of Delta(solv)H(m) in the binary subcritical fluid is larger than that in pure CO(2) in the high-compressible region of the mixed solvent. The main reason for this is that the degree of clustering in the SC solutions is small at the density in which the degree of clustering is large in the subcritical solutions. It can be concluded that solubility enhancement by n-pentane in the mixed SC fluid is entropy driven. In contrast, the solubility enhancement by n-pentane in subcritical fluids is enthalpy driven. The intermolecular interaction in the SC solutions and subcritical solutions can be significantly different even if their densities are the same.

Topics: Carbon Dioxide; Chemical Phenomena; Chemistry, Physical; Naphthoquinones; Pentanes; Solubility; Solutions; Solvents; Thermodynamics

The photochemistry of 1,4-naphthoquinone (NQ), the 2-methyl, 2,3-dichloro and 2-bromo derivatives, and vitamin K(1) was studied in non-aqueous solvents by time-resolved UV-vis spectroscopy after ns laser pulses at 248 and 308 nm. The triplet state of the NQs reacts with alcohols and amines, e.g. triethylamine (TEA) and DABCO, yielding semiquinone radicals (HQ(*)/Q (*)(-)). They are the major intermediates and their second-order decay kinetics depend on the properties of the additives and the medium. Transient conductivity measurements suggest the occurrence of photoinduced electron transfer from amines to the triplet state of NQs in acetonitrile. The photoconversion lambda (irr)= 254 nm) of NQs to the 1,4-dihydroxynaphthalenes (H(2)Q) was measured in the absence and presence of varying concentrations of electron and H-atom donors, and the quantum yield was found to increase with increasing electron- or proton-donor concentration. The mechanisms of photoreduction of NQs by propan-2-ol and TEA in acetonitrile exhibit a number of similarities. Oxygen quenches the triplet state, thereby forming singlet molecular oxygen. Oxygen also reacts with the semiquinone radical, thereby forming HO(2)(*)/O(2) (*) (-) radicals, and reacts with H(2)Q, thereby re-forming the quinone. A different pattern, involving intramolecular H-atom transfer, holds for vitamin K(1), where 1,3-quinone methide (1,3-QM) diradicals were observed in acetonitrile prior to formation of two 1,2-QM tautomers, but a triplet was not. The decay of the 1,3-QM intermediates becomes faster in the presence of alcohols and amines due to proton-transfer reactions.

Topics: Alcohols; Amines; Ethanol; Naphthoquinones; Photochemistry; Solutions; Vitamin K

A series of 1,4-naphthoquinone derivatives were synthesized and tested for antifungal and antitumor activity against a number of fungal disease causative species and Walker 256 carcinoma cell lines. The results show that the compounds 8a,e and 11b possess pronounced antifungal profile where as 7b and f were found to be active against Walker 256 carcinoma cell lines. Moreover 7c and 11a showed inhibitory effect against reverse transcriptase enzyme from Rauscher Murine Leukemia Virus.

Topics: Animals; Antifungal Agents; Antineoplastic Agents; Carcinoma 256, Walker; Drug Design; Drug Evaluation, Preclinical; Microbial Sensitivity Tests; Naphthoquinones

The antiplatelet and antithrombotic activities of a newly synthesized CP201, 2-(3,5-di-tert-butyl-4-hydroxyl)-3-chloro-1,4-naphthoquinone on human platelet aggregation in vitro and murine pulmonary thrombosis in vivo were examined. In addition, the antiplatelet activity of CP201 involved in calcium-signaling cascade was also investigated. CP201 showed concentration-dependent inhibitory effects on platelet aggregation induced by collagen and thrombin, with IC50 values of 4.1+/-0.3 and 4.6+/-0.4 microM, respectively. Orally administered CP201 protected mice against the collagen plus epinephrine-induced thromboembolic death in a dose-dependent manner. On the other hand, CP201 did not alter such coagulation parameters as activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) in human plasma in vitro. These results suggest that the antithrombotic activity of CP201 may be due to antiplatelet rather than anticoagulation activity. CP201 potently inhibited platelet aggregation challenged by calcium ionophore A23187 and thapsigargin, which is a selective inhibitor of the Ca(2+)-ATPase pump, in a concentration-dependent manner, indicating that CP201 may have an inhibitory effect on calcium-signaling cascade. This was supported by measuring [Ca2+]i in platelets loaded with fura-3AM, where CP201 inhibited the rise in cytosolic Ca2+ mediated by thrombin. Taken together, these results suggest that CP201 may be a promising antithrombotic agent, and the antithrombotic effect of CP201 may be due to antiplatelet activity, which was mediated, at least partly, by the inhibition of cytosolic calcium mobilization.

Topics: Animals; Dose-Response Relationship, Drug; Fibrinolytic Agents; Humans; Male; Mice; Mice, Inbred ICR; Naphthoquinones; Platelet Aggregation; Platelet Aggregation Inhibitors; Pulmonary Embolism

Ortho-quinones 1,10-phenanthroquinone and beta-lapachone but not para-quinones naphthazarin (NZQ) and 1,4-naphthoquinone enhance ascorbate oxidation in the presence of MgCl(2) and CaCl(2) at constant ionic strength. Alkaline-earth cation chelation is observed for the ortho-semiquinones but not for the para-semiquinones, while no interaction between these quinones (with the exception of NZQ) or ascorbate and these salts was detected, suggesting that semiquinone-metal complexes are responsible for the catalytic action on ascorbate oxidation of these metal salts in the presence of these ortho-quinones. Thus, redox cycling efficiency of the quinones under study here, in the presence of ascorbate, depends not only on the quinone redox potential but also on the semiquinone ability to chelate alkaline-earth cations.

Topics: Ascorbic Acid; Electron Spin Resonance Spectroscopy; Metals, Alkaline Earth; Naphthoquinones; Oxidation-Reduction; Quinones

The antimicrobial effect of 5 naphthoquinones was tested against the phytopathogenic bacteria Erwinia carotovora. Disk diffusion tests and determination of minimal inhibitory concentrations (MIC) indicate that the compound naphthazarin (NTZ) has the best antibacterial activity among the naphthoquinones tested. Studies on the mode of action indicate the effect of NTZ was bactericidal at 10 microg/mL. When cultivation was done in the presence of sodium ascorbate, the restoration of E. carotovora growth was observed with 3 microg/mL NTZ, but not when a 10 microg/mL dose was used. The incubation of NTZ with bacterial suspension of E. carotovora resulted in important changes in the absorption spectra of this naphthoquinone, indicating that a redox reaction takes place. These results may suggest that NTZ induces an increase of reactive oxygen species that are toxic to the cell. The compound NTZ was also effective in preventing E. carotovora growth on potato tubers, inhibiting the soft rot development at a concentration of 2 mg/mL.

Topics: Anti-Bacterial Agents; Microbial Sensitivity Tests; Naphthoquinones; Pectobacterium carotovorum; Plant Diseases; Solanum tuberosum

NAD(P)H/quinone acceptor oxidoreductase type 1 (QR1) protects cells from cytotoxic and neoplastic effects of quinones though two-electron reduction. Kinetic experiments, docking, and binding affinity calculations were performed on a series of structurally varied quinone substrates. A good correlation between calculated and measured binding affinities from kinetic determinations was obtained. The experimental and theoretical studies independently support a model in which quinones (with one to three fused aromatic rings) bind in the QR1 active site utilizing a pi-stacking interaction with the isoalloxazine ring of the FAD cofactor.

Topics: Animals; Anthraquinones; Benzoquinones; Binding Sites; Flavins; Humans; Kinetics; Models, Chemical; Models, Molecular; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Rats; Structure-Activity Relationship; Substrate Specificity; Thermodynamics; Tyrosine

The toxicity of four quinones, 2,3-dimethoxy-1,4-naphthoquinone (DMONQ), 2-methyl-1,4-naphthoquinone (MNQ), 1,4-naphthoquinone (NQ), and 1,4-benzoquinone (BQ), which redox cycle or arlyate in mammalian cells, was determined in isolated trout (Oncorhynchus mykiss) hepatocytes. More than 70% of cells died in 3 h when exposed to BQ or NQ; 50% died in 7 h when exposed to MNQ, with no mortality compared to controls after 7 h DMONQ exposure. A suite of biochemical parameters was assessed for ability to discriminate these reactivity pathways in fish. Rapid depletion of glutathione (GSH) with appearance of glutathione disulfide (GSSG) and increased dichlorofluoroscein fluorescence were used as indicators of redox cycling, noted with DMONQ, MNQ, and NQ. Depletion of GSH with no GSSG accumulation, and loss of free protein thiol (PrSH) groups (nonreducible) indicated direct arylation by BQ. All toxicants rapidly oxidized NADH, with changes in NADPH noted later (BQ, NQ, MNQ) or not at all (DMONQ). Biochemical measures including cellular energy status, cytotoxicity, and measures of reactive oxygen species, along with the key parameters of GSH and PrSH redox status, allowed differentiation of responses associated with lethality. Chemicals that arylate were more potent than redox cyclers. Toxic pathway discrimination is needed to group chemicals for potency predictions and identification of structural parameters associated with distinct types of reactive toxicity, a necessary step for development of mechanistically based quantitative structure-activity relationships (QSARs) to predict chemical toxic potential. The commonality of reactivity mechanisms between rodents and fish was also demonstrated, a step essential for species extrapolations.

Topics: Adenine; Animals; Benzoquinones; Cell Death; Female; Glutathione; Glutathione Disulfide; Hepatocytes; Male; Molecular Structure; Naphthoquinones; Oncorhynchus mykiss; Oxidation-Reduction; Oxygen; Pyridines; Quantitative Structure-Activity Relationship; Reactive Oxygen Species; Sulfhydryl Compounds; Vitamin K 3

Many aspects of the toxicity of xenobiotic compounds have been attributed to the consequences of covalent modification of specific proteins, but the nature and specificity of protein targets for classes of electrophilic toxins remain largely uncharacterized. For inhaled toxicants, the point of exposure or absorption lies with epithelial cells lining the pulmonary tree. In this study, abundant proteins in human bronchial epithelial cells that are arylated in vitro by two quinonoid compounds, 1,4-benzoquinone (BQ) and 1,4-naphthoquinone (NQ) have been detected using (14)C-labeled quinones and two-dimensional gel electrophoresis. These proteins were identified using matrix assisted laser desorption/ionization mass spectrometry for tryptic mass mapping followed by sequence database searching. Corroborative identification of protein targets was obtained from the apparent isoelectric points, molecular weights, and the use of antibody probes. There were subtle differences in the protein targets of BQ and NQ, but both associated with the following abundant proteins, nucleophosmin, galectin-1, probable protein disulfide isomerase, protein disulfide isomerase, 60 kDa heat shock protein, mitochondrial stress-70 protein, epithelial cell marker protein, and S100-type calcium binding protein A14. We further delineate the properties of these proteins that make them preferred targets and the evidence these adducts present for delivery of these quinones to subcellular compartments.

Topics: Adolescent; Adult; Amino Acid Sequence; Autoradiography; Benzoquinones; Bronchi; Cells, Cultured; Electrophoresis, Gel, Two-Dimensional; Epithelial Cells; Female; Humans; Male; Mass Spectrometry; Naphthoquinones; Oxidation-Reduction; Peptide Mapping; Proteins

Both 1,4-benzoquinones and 1,4-naphthoquinones were attached to the non-proteinogenic amino acid taurine to form N-quinonyl taurine derivatives. The products were formed via the direct Michael-like addition or by substitution of a good leaving group. An attempt to bridge the two moieties via an ureido spacer resulted in the formation of a bis-quinonylamino isocyanurate derivative. Preliminary MO calculations provided internal ground-state geometries and orbital coefficients of the HOMO levels in two representing taurine conjugates.

Topics: Benzoquinones; Models, Chemical; Models, Molecular; Molecular Structure; Naphthoquinones; Quinones; Taurine

The antifungal activity of 1,4-naphthoquinones, 1,2-naphthoquinones, 1,4-benzoquinones, and anthraquinones from our natural products collection was tested by direct bioautography to identify natural products with potential use in agricultural fungal pathogen control. Quinones demonstrated good to moderate antifungal activity against Colletotrichum spp. Colletotrichum fragariae was the most sensitive species to quinone-based chemistry, Colletotrichum gloeosporioides had intermediate sensitivity, while Colletotrichum acutatum was the species least sensitive to these compounds.

Topics: Anthraquinones; Benzoquinones; Colletotrichum; Fungicides, Industrial; Naphthoquinones; Quinones

The feasibility of atmospheric pressure desorption/ionization on silicon mass spectrometry (AP-DIOS-MS) for drug analysis was investigated. It was observed that only compounds with relative high proton affinity are efficiently ionized under AP-DIOS conditions. The limits of detection (LODs) achieved in MS mode with midazolam, propranolol, and angiotensin II were 80 fmol, 20 pmol, and 1 pmol, respectively. In MS/MS mode the LODs for midazolam and propranolol were 10 fmol and 5 pmol, respectively. The good linearity (r(2) > 0.991), linear dynamic range of 3 orders of magnitude, and reasonable repeatability showed that the method is suitable for quantitative analysis.

Topics: Acetaminophen; Air Ionization; Atmospheric Pressure; Carboxylic Acids; Ketoprofen; Mass Spectrometry; Midazolam; Molecular Structure; Naphthaleneacetic Acids; Naphthalenes; Naphthoquinones; Pharmaceutical Preparations; Propranolol; Silicon; Testosterone

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that are converted to cytotoxic and carcinogenic metabolites, quinones, by detoxifying enzyme systems in animals. PAH metabolites such as the quinones can form Michael adducts with biological macromolecules containing reactive nucleophiles, making detection of exposure to PAHs difficult using conventional techniques. A technique has been developed for detecting exposure to PAHs. Tetramethylammonium hydroxide (TMAH) thermochemolysis coupled with GC/MS is proposed as an assay method for PAH quinones that have formed Michael adducts with biological molecules. Three PAH quinones (1,4-naphthoquinone, 1,2-naphthoquinone, and 1,4-anthraquinone) and 1,4-benzoquinone were reacted with cysteine, and the TMAH thermochemolysis method was used to assay for both thiol and amine adduction between the quinones and the cysteine. Additional studies with 1,4-naphthoquinone adducts to glutathione and bovine serum albumin showed the same thiol and amine TMAH thermochemolysis products with larger peptides as was observed with cysteine adducts. The TMAH GC/MS method clearly shows great promise for detecting PAH quinones, produced by enzymatic conversion of PAHs in biological systems, that have been converted to respective Michael adducts.

Topics: Animals; Anthraquinones; Benzoquinones; Cattle; Cysteine; Evaluation Studies as Topic; France; Gas Chromatography-Mass Spectrometry; Glutathione; Molecular Structure; Naphthoquinones; Polycyclic Aromatic Hydrocarbons; Quaternary Ammonium Compounds; Serum Albumin, Bovine

The antibacterial activity of a series of 1,4-naphthoquinones was demonstrated. Disk diffusion tests were carried out against several Gram-positive and Gram-negative bacteria. The compound 5-amino-8-hydroxy-1,4-naphthoquinone was the most effective, presenting inhibition zones measuring 20 mm against staphylococci, streptococci and bacilli at 50 microg/ml. Methicillin-resistant Staphylococcus aureus and several clinical isolates of this bacterium were also inhibited. Naphthazarin, 5-acetamido-8-hydroxy-1,4-naphthoquinone, and 2,3-diamino-1,4-naphthoquinone were the next most active compounds. The minimal inhibitory concentration of the active compounds was determined against S. aureus, ranging from 30 to 125 microg/ml. All compounds presented a minimal bactericidal concentration higher than 500 microg/ml, indicating that their effect was bacteriostatic. The EC50, defined as the drug concentration that produces 50% of maximal effect, was 8 microg/ml for 5-amino-8-hydroxy-1,4-naphthoquinone against S. aureus, S. intermedius, and S. epidermidis. These results indicate an effective in vitro activity of 5-amino-8-hydroxy-1,4-naphthoquinone and encourage further studies for its application in antibiotic therapy.

Topics: Animals; Anti-Bacterial Agents; Drug Resistance, Microbial; Gram-Negative Bacteria; Gram-Positive Bacteria; Listeria; Microbial Sensitivity Tests; Naphthoquinones; Sheep; Staphylococcus aureus; Streptococcus

Naphthalene is an important industrial chemical, which has recently been shown to cause tumors of the respiratory tract in rodents. It is thought that one or more reactive metabolites of naphthalene, namely, naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ), and 1,4-naphthoquinone (1,4-NPQ) contribute to the tumorigenicity of this chemical. These electrophiles are all capable of covalent binding to macromolecules including DNA and proteins. The stability of cysteinyl adducts of NPO, 1,2-NPQ, and 1,4-NPQ were investigated in both hemoglobin (Hb) and albumin (Alb) of male F344 rats following a single administration of 2 different doses (400 or 800 mg naphthalene per kg body weight). To assess the stability of Alb adducts, we compared the rates of NPO-Alb turnover (half-life of approximately 2 days) and 1,2-NPQ-Alb (half-life of approximately 1 day) to the normal turnover rate of Alb in the rat (half-life = 2.5-3 days). Based on the rapid turnover of these adducts relative to Alb itself, we concluded that they were unstable. However, the stability of Alb adducts was not affected by the dose of naphthalene administered (400 or 800 mg/kg). In contrast, NPO-Hb adducts were relatively stable (rate constant of adduct instability

Topics: Albumins; Animals; Biotransformation; Cysteine; Dose-Response Relationship, Drug; Half-Life; Hemoglobins; Male; Models, Biological; Naphthalenes; Naphthoquinones; Protein Binding; Rats; Rats, Inbred F344; Time Factors

Naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ) and 1,4-naphthoquinone (1,4-NPQ) are the major metabolites of naphthalene that are thought to be responsible for the cytotoxicity and genotoxicity of this chemical. We measured cysteinyl adducts of these metabolites in hemoglobin (Hb) and albumin (Alb) from F344 rats dosed with 100-800 mg naphthalene per kg body weight. The method employs cleavage and derivatization of these adducts by trifluoroacetic anhydride and methanesulfonic acid followed by gas chromatography-mass spectrometry in negative ion chemical ionization mode. Cysteinyl adducts of both proteins with NPO, and 1,2- and 1,4-NPQ (designated NPO-Hb and -Alb, 1,2-NPQ-Hb and -Alb, and 1,4-NPQ-Hb and -Alb, respectively) were produced in a dose-dependent manner. Of the two structural isomers resulting from NPO, levels of NPO1 adducts were greater than those of NPO2 adducts in both Hb and Alb, indicating that aromatic substitution is favored in vivo at positions 1 over 2. Of the quinone adducts, 1,2-NPQ-Hb and -Alb were produced in greater quantities than 1,4-NPQ-Hb and -Alb, indicating either that the formation of 1,2-NPQ from NPO is favored or that more than one pathway leads to the formation of 1,2-NPQ. The shapes of the dose-response curves were generally nonlinear at doses above 200 mg naphthalene per kg body weight. However, the nature of nonlinearity differed, showing evidence of supralinearity for NPO-Hb, NPQ-Hb and NPQ-Alb and of sublinearity for NPO-Alb. Low background levels of 1,2-NPQ-Hb and -Alb and 1,4-NPQ-Hb and -Alb were detected in control animals without known exposure to naphthalene. However, the corresponding NPO-Hb and -Alb adducts were not detected in control animals.

Topics: Acetylcysteine; Animals; Gas Chromatography-Mass Spectrometry; Hemoglobins; Humans; Male; Mesylates; Molecular Structure; Naphthalenes; Naphthoquinones; Protein Binding; Rats; Rats, Inbred F344; Sensitivity and Specificity; Serum Albumin

Quinones have been shown to possess antineoplastic activity; however, their effects on ionic currents remain unclear. The effects of 2-mercaptophenyl-1,4-naphthoquinone (2-MPNQ), menadione (MD) and 1,4-naphthoquinone (1,4 NQ) on cell proliferation and ionic currents in pituitary GH3 lactotrophs were investigated in this study. 2-MPNQ was more potent than menadione or 1,4-naphthoquinone in inhibiting the growth of GH3 cells. 2-MPNQ decreased cell proliferation in a concentration-dependent manner with an IC50 value of 3 microM. In whole-cell recording experiments, 2-MPNQ reversibly caused an inhibition of Ca2+-activated K+ current (I(K(Ca)) in a concentration-dependent manner. The IC50 value for 2-MPNQ-induced inhibition of I(K(Ca)) was 7 microM. In the inside-out configuration of single channel recording, 2-MPNQ (30 microM) applied intracellularly suppressed the activity of large-conductance Ca2+-activated K+ (BK(Ca)) channels but did not modify single channel conductance. Menadione (30 microM) had no effect on the channel activity, whereas 1,4-naphthoquinone (30 microM) suppressed it by about 26%. Both 2-MPNQ and thimerosal suppressed the dithiothreitol-stimulated channel activity. 2-MPNQ also blocked voltage-dependent K+ currents, but it produced a slight reduction of L-type Ca2+ inward current. However, unlike E-4031, 2-MPNQ (30 microM) did not suppress inwardly rectifying K+ current present in GH3 cells. Under the current clamp configuration, the presence of 2-MPNQ (30 microM) depolarized the cells, and increased the frequency and duration of spontaneous action potentials. The 2-MPNQ-mediated inhibition of K+ currents would affect hormone secretion and cell excitability. The blockade of these ionic channels by 2-MPNQ may partly explain its inhibitory effect on the proliferation of GH3 cells.

Topics: Action Potentials; Animals; Calcium; Calcium Channels, L-Type; Cell Division; Dose-Response Relationship, Drug; Naphthoquinones; Pituitary Neoplasms; Potassium Channels; Rats; Thimerosal; Tumor Cells, Cultured; Vitamin K 3

Aloe is a familiar ingredient in a wide range of health care and cosmetic products and has been reported to possess various physiological effects, antioxidative, anticarcinogenic, antiinflammatory and laxative. Aloe has also been reported to have an effect on liver function. The cytoprotective effect of aloe extract against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone (100 microM), a decrease in cell viability measured as >60% lactate dehydrogenase depletion was induced. Cellular glutathione (GSH) and protein-SH levels were also significantly decreased in a time-dependent manner. However addition of aloe extract resulted in a dose-dependent improvement of these effects. This cytoprotective effect of aloe could be attributed to its inhibition of GSH and protein-SH depletions. The effect of the aloe extracts were also dose-dependent. Addition of diethyl maleate (1 mM), a cellular glutathione-depleting agent, to hepatocytes treated with both 1,4-naphthoquinone and aloe extract, induced depletion of GSH, but did not affect protein-SH or lactate dehydrogenase. These results suggest that the 1,4-naphthoquinone-induced toxicity in rat hepatocytes was inhibited by aloe extract, and that this protective effect was due to the maintenance of cellular thiols, especially protein-SH.

Topics: Aloe; Animals; Cells, Cultured; Glutathione; Hepatocytes; L-Lactate Dehydrogenase; Male; Naphthoquinones; Plant Extracts; Protective Agents; Rats; Rats, Sprague-Dawley; Sulfhydryl Compounds

Atovaquone is a chemotherapeutic agent used to treat pneumonia caused by Pneumocystis carinii in some immunocompromised patients. A set of cyclic 1,4-diones were tested in vitro for ability to inhibit growth of P. carinii, including 22 variously substituted 1,4-naphthoquinones, one bis-1,4-naphthoquinone, and three other quinones. For comparison, the antipneumocystic primaquine and its 5-hydroxy-6-desmethyl metabolite were also tested. At 1.0 microg/ml, seven compounds inhibited growth by at least 39%, with atovaquone at 92%; of these seven, five are 2-hydroxy-1,4-naphthoquinones, while one is a 2-chloro- and another is a 2-methyl-1,4-naphthoquinone. At 0.1 microg/ml, however, the most active compound tested was the primaquine metabolite, which inhibited growth by more than 42% at this concentration. To ascertain a structure-activity relationship, all 1,4-naphthoquinones were compared conformationally by means of computer-based molecular modeling (Spartan) incorporating the Sybyl force field. Without exception, for all 21 monomers tested, the substituent at position 3 of the 1,4-naphthoquinone favored activity most strongly when it simultaneously occupied (i) space centered at about 3 A from position 3, without projecting steric bulk from the area encompassed by atovaquone's cyclohexyl ring, and (ii) roughly planar space at about 7.3 A from position 3, without projecting steric bulk perpendicularly. This structure-activity relationship may prove useful in the rational design of better antipneumocystis agents.

Topics: Antifungal Agents; Humans; Microbial Sensitivity Tests; Naphthoquinones; Pneumocystis; Structure-Activity Relationship

Various anti-platelet drugs, including quinones, are being investigated as potential treatments for cardiovascular disease because of their ability to prevent excessive platelet aggregation. In the present investigation 3 naphthoquinones (2,3-dimethoxy-1,4-naphthoquinone [DMNQ], menadione, and 1,4-naphthoquinone [4-NQ]) were compared for their abilities to inhibit platelet aggregation, deplete glutathione (GSH) and protein thiols, and cause cytotoxicity. Platelet-rich plasma, isolated from Sprague-Dawley rats, was used for all experiments. The relative potency of the 3 quinones to inhibit platelet aggregation, deplete intracellular GSH and protein thiols, and cause cytotoxicity was 1,4-NQ > menadione >> DMNQ. Experiments using 2 thiol-modifying agents, dithiothreitol (DTT) and 1-chloro-2,4-dintrobenzene (CDNB), confirmed the key roles for GSH in quinone-induced platelet anti-aggregation and for protein thiols in quinone-induced cytotoxicity. Furthermore, the anti-aggregative effects of a group of 12 additional quinone derivatives were positively correlated with their ability to cause platelet cytotoxicity. Quinones that had a weak anti-aggregative effect did not induce cytotoxicity (measured as LDH leakage), whereas quinones that had a potent anti-aggregative effect resulted in significant LDH leakage (84-96%). In one instance, however, p-chloranil demonstrated a potent anti-aggregative effect, but did not induce significant LDH leakage. This can be explained by the inability of p-chloranil to deplete protein thiols, even though intracellular GSH levels decreased rapidly. These results suggest that quinones that deplete GSH in platelets demonstrate a marked anti-aggregative effect. If this anti-aggregative effect is subsequently followed by depletion of protein thiols, cytotoxicity results.

Topics: Animals; Blood Platelets; Cell Survival; Chloranil; Dinitrochlorobenzene; Dithiothreitol; Female; Glutathione; L-Lactate Dehydrogenase; Naphthoquinones; Platelet Aggregation; Proteins; Rats; Rats, Sprague-Dawley; Sulfhydryl Compounds; Vitamin K

Interruption of the phylloquinone (PhQ) biosynthetic pathway by interposon mutagenesis of the menA and menB genes in Synechocystis sp. PCC 6803 results in plastoquinone-9 (PQ-9) occupying the A(1) site and functioning in electron transfer from A(0) to the FeS clusters in photosystem (PS) I (Johnson, T. W., Shen, G., Zybailov, B., Kolling, D., Reategui, R., Beauparlant, S., Vassiliev, I. R., Bryant, D. A., Jones, A. D., Golbeck, J. H., and Chitnis, P. R. (2000) J. Biol. Chem. 275, 8523-8530. We report here the isolation of menB26, a strain of the menB mutant that grows in high light by virtue of a higher PS I to PS II ratio. PhQ can be reincorporated into the A(1) site of the menB26 mutant strain by supplementing the growth medium with authentic PhQ. The reincorporation of PhQ also occurs in cells that have been treated with protein synthesis inhibitors, consistent with a displacement of PQ-9 from the A(1) site by mass action. The doubling time of the menB26 mutant cells, but not the menA mutant cells, approaches the wild type when the growth medium is supplemented with naphthoquinone (NQ) derivatives such as 2-CO(2)H-1,4-NQ and 2-CH(3)-1,4-NQ. Since PhQ replaces PQ-9 in the supplemented menB26 mutant cells, but not in the menA mutant cells, the phytyl tail accompanies the incorporation of these quinones into the A(1) site. Studies with menB26 mutant cells and perdeuterated 2-CH(3)-1,4-NQ shows that phytylation occurs at position 3 of the NQ ring because the deuterated 2-methyl group remains intact. Therefore, the specificity of the phytyltransferase enzyme is selective with respect to the group present at ring positions 2 and 3. Supplementing the growth medium of menB26 mutant cells with 1,4-NQ also leads to its incorporation into the A(1) site, but typically without either the phytyl tail or the methyl group. These findings open the possibility of biologically incorporating novel quinones into the A(1) site by supplementing the growth medium of menB26 mutant cells.

Topics: Alkyl and Aryl Transferases; Chlorophyll; Cyanobacteria; Electron Spin Resonance Spectroscopy; Free Radicals; Genes, Bacterial; Light; Light-Harvesting Protein Complexes; Mutation; Naphthoquinones; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Plastoquinone; Vitamin K 1; Vitamin K 3

Topics: Anti-Inflammatory Agents; Antiparasitic Agents; Bromine; Naphthoquinones

Interaction of camel lens zeta-crystallin, an NADPH:quinone oxidoreductase, with several quinone derivatives was examined by fluorescence spectroscopy and activity measurements. Fluorescence of zeta-crystallin was quenched to different levels by the different quinones:juglone (5-OH, 1,4 naphthoquinone), 1,4 naphthoquinone (1,4-NQ), and 1,2 naphthoquinone (1,2-NQ) considerably quenched the fluorescence of zeta-crystallin, where as the commonly used substrate, 9,10-phenanthrenequinone (PQ) did not induce significant quenching. Activity measurements showed only PQ served as a substrate for camel lens zeta-crystallin, while juglone, 1,4-NQ, and 1,2-NQ were inhibitors. Thus quinones that interacted with zeta-crystallin directly inhibited the enzyme, whereas the substrate had very low affinity for the enzyme in the absence of NADPH. Another substrate, dichlorophenol indophenol (DCIP), conformed to the same pattern; DCIP did not quench the fluorescence of the enzyme significantly, but served as a substrate. This pattern is consistent with an ordered mechanism of catalysis with quinone being the second substrate. All three naphthoquinones were uncompetitive inhibitors with respect to NADPH and noncompetitive with respect to PQ. These kinetics are similar to those exhibited by cysteine- and/or lysine-modifying agents. Juglone, 1,4-NQ, and 1,2-NQ interacted with and quenched the fluorescence of camel lens alpha-crystallin, but to lesser extent than that of zeta-crystallin.

Topics: 2,6-Dichloroindophenol; Animals; Camelus; Catalysis; Crystallins; Cysteine; Dose-Response Relationship, Drug; Kinetics; Lens, Crystalline; Ligands; NADP; Naphthoquinones; Protein Binding; Spectrometry, Fluorescence

Topics: Animals; Anthracenes; Benz(a)Anthracenes; DNA Damage; Fluorenes; Fresh Water; Glutathione; Mice; Models, Biological; Molecular Structure; Naphthoquinones; Oxidative Stress; Polycyclic Aromatic Hydrocarbons; Quinones; Tumor Cells, Cultured; Vitamin K 3

Flash-induced redox changes of b-type and c-type cytochromes have been studied in chromatophores from the aerobic photosynthetic bacterium Roseobacter denitrificans under redox-controlled conditions. The flash-oxidized primary donor P+ of the reaction center (RC) is rapidly re-reduced by heme H1 (Em,7 = 290 mV), heme H2 (Em,7 = 240 mV) or low-potential hemes L1/L2 (Em,7 = 90 mV) of the RC-bound tetraheme, depending on their redox state before photoexcitation. By titrating the extent of flash-induced low-potential heme oxidation, a midpoint potential equal to -50 mV has been determined for the primary quinone acceptor QA. Only the photo-oxidized heme H2 is re-reduced in tens of milliseconds, in a reaction sensitive to inhibitors of the bc1 complex, leading to the concomitant oxidation of a cytochrome c spectrally distinct from the RC-bound hemes. This reaction involves cytochrome c551 in a diffusional process. Participation of the bc1 complex in a cyclic electron transfer chain has been demonstrated by detection of flash-induced reduction of cytochrome b561, stimulated by antimycin and inhibited by myxothiazol. Cytochrome b561, reduced upon flash excitation, is re-oxidized slowly even in the absence of antimycin. The rate of reduction of cytochrome b561 in the presence of antimycin increases upon lowering the ambient redox potential, most likely reflecting the progressive prereduction of the ubiquinone pool. Chromatophores contain approximately 20 ubiquinone-10 molecules per RC. At the optimal redox poise, approximately 0.3 cytochrome b molecules per RC are reduced following flash excitation. Cytochrome b reduction titrates out at Eh < 100 mV, when low-potential heme(s) rapidly re-reduce P+ preventing cyclic electron transfer. Results can be rationalized in the framework of a Q-cycle-type model.

Topics: Antimycin A; Bacteria; Bacterial Physiological Phenomena; Benzoquinones; Cytochrome b Group; Cytochrome c Group; Electron Transport Complex III; Electrons; Enzyme Inhibitors; Ferricyanides; Kinetics; Light; Methacrylates; Naphthoquinones; Oxidation-Reduction; Phenylenediamines; Photosynthesis; Photosynthetic Reaction Center Complex Proteins; Proteobacteria; Thiazoles; Time Factors; Titrimetry

The rates of autoxidation of a number of pure naphthohydroquinones have been determined, and the effects of pH, superoxide dismutase (SOD) and of the parent naphthoquinone on the oxidation rates have been investigated. Most compounds were slowly oxidised in acid solution with the rates increasing with increasing pH, although 2-hydroxy-, 2-hydroxy-3-methyl- and 2-amino-1,4-naphthohydroquinone were rapidly oxidised at pH 5 and the rates of oxidation of these substances were comparatively unresponsive to changes in pH. At pH 7.4, autoxidation rates decreased in the order 2,3-dichloro-1,4-naphthohydroquinone > 5-hydroxy > 2-bromo > 2-hydroxy-3-methyl > 2-amino > 2-hydroxy > 2-methoxy > 2,3-dimethoxy > 2,3-dimethyl > 2-methyl > unsubstituted hydroquinone. The autoxidation rates of the alkyl, alkoxy, hydroxy and amino derivatives were decreased in the presence of SOD, but this enzyme had no effect on the rate of autoxidation of the 2,3-dichloro and 2-bromo derivatives while that of the 5-hydroxy derivative was increased. The rates of autoxidation of all compounds except the halogen derivatives and 5-hydroxy-1,4-naphthohydroquinone were increased by addition of the parent naphthoquinone, and quinone addition partially or completely overcame the inhibitory effect of SOD. There is evidence that the reduction of quinones to hydroquinones in vivo may lead either to detoxification or to activation. This may be due to differences in the rate or mechanism of autoxidation of the hydroquinones that are formed, and the data gained in this study will provide a framework for testing this possibility.

Topics: Animals; Cattle; Electrochemistry; Erythrocytes; Hydrogen-Ion Concentration; Hydroquinones; Kinetics; Naphthoquinones; Oxidation-Reduction; Oxygen; Superoxide Dismutase

Solid- and solution-phase parallel syntheses of 1,4-naphthoquinones (1,4-NQ) are described. A library of 1360 amides was constructed from the combination of 12 newly synthesised 1,4-NQ carboxylic acid and 120 amines, and was screened for inhibition of trypanothione reductase (TR) from Trypanosoma cruzi. The most active hits from a primary screening were re-synthesised and confirmed. This approach proves that it is possible to design potent and highly specific TcTR inhibitors deriving from menadione, juglone and plumbagin.

Topics: Animals; Antiprotozoal Agents; Automation; Drug Evaluation, Preclinical; Inhibitory Concentration 50; NADH, NADPH Oxidoreductases; Naphthoquinones; Quality Control; Trypanosoma cruzi

The human colon carcinoma cell lines Caco-2 and HT-29 were exposed to three structurally related naphthoquinones. Menadione (MEN), 1,4-naphthoquinone (NQ), and 2,3-dimethoxy-1,4-naphthoquinone (DIM) redoxcycle at similar rates, NQ is a stronger arylator than MEN, and DIM does not arylate thiols. The Caco-2 cell line was particularly vulnerable to NQ and MEN and displayed moderate toxic effects of DIM. The HT-29 cell line was only vulnerable to NQ and MEN after inhibition of DT-diaphorase (DTD) with dicoumarol, whereas dicoumarol did not affect the toxicity of quinones to Caco-2 cells. DTD activity in the HT-29 and Caco-2 cell lines, as estimated by the dicoumarol-sensitive reduction of 2,6-dichlorophenolindophenol, was 393.7 +/- 46.9 and 6.4 +/- 2.2 nmol NADPH x min(-1) x mg protein(-1), respectively. MEN depleted glutathione to a small extent in the HT-29 cell line, but a rapid depletion similar to Caco-2 cells was achieved when dicoumarol was added. The data demonstrated that the DTD-deficient Caco-2 cell line was more vulnerable to arylating or redoxcycling quinones than DTD-expressing cell lines. Exposure of the Caco-2 cell line to quinones produced a rapid rise in protein disulphides and oxidised glutathione. In contrast to NQ and DIM, no intracellular GSSG was observed with MEN. The relatively higher levels of ATP in MEN-exposed cells may account for the efficient extrusion of intracellular GSSG. The reductive potential of the cell as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide reduction was only increased by MEN and not with NQ and DIM. We conclude that arylation is a major contributing factor in the toxicity of quinones. For this reason, NQ was the most toxic quinone, followed by MEN, and the pure redoxcycler DIM elicited modest toxicity in Caco-2 cells.

Topics: Adenosine Triphosphate; Cell Survival; Colonic Neoplasms; Dicumarol; Glutathione; Glutathione Disulfide; Humans; Kinetics; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Neoplasm Proteins; Sulfhydryl Compounds; Tumor Cells, Cultured; Vitamin K

One-electron reduction of quinones (Q) by ascorbate (AscH ); (1) AscH + Q --> Q*- + Asc*- + H+, followed by the oxidation of semiquinone (Q*-) by molecular oxygen; (2) Q*- + O2 --> Q + O2*-, results in the catalytic oxidation of ascorbate (with Q as a catalyst) and formation of active forms of oxygen. Along with enzymatic redox cycling of Q. this process may be related to Q cytotoxicity and underlie an antitumor activity of some Qs. In this work, the kinetics of oxygen consumption accompanied the interaction of ascorbate with 55 Qs including substituted 1,4- and 1,2-benzoquinones, naphthoquinones and other quinoid compounds were studied in 50 mM sodium phosphate buffer, pH 7.40, at 37 degrees C by using the Clark electrode technique. The capability of Q to catalyze ascorbate oxidation was characterized by the effective value of kEFF calculated from the initial rate of oxygen consumption (R(OX)) by the equation R(OX) = kEFF[Q][AscH-] as well as by a temporary change in R(OX). The correlation of kEFF with one-electron reduction potential, E(Q/Q*-), showed a sigma-like plot, the same for different kinds of Qs. Only the Qs which reduction potential E(Q/Q*-) ranged from nearly -250 to + 50 mV displayed a pronounced catalytic activity, kEFF increased with shifting E(Q/Q*-) to positive values. The following linear correlation between kEFF (in M (-1) s(-1)) and E(Q/Q*-) (in mV) might be suggested for these Qs: lg(kEFF)= 3.91 + 0.0143E(Q/Q*-). In contrast, Qs with E(Q/Q*-) < - 250 mV and E(Q/Q*-) > + 50 mV showed no measurable catalytic activity. The Qs studied displayed a wide variety in the kinetic regularities of oxygen consumption. When E(Q/Q*-) was more negative than - 100 mV, Q displayed a simple ('standard') kinetic behavior--R(OX) was proportional to [AscH-][Q] independently of concentration of individual reagents, [AscH-] and [Q]; R(OX) did not decrease with time if [AscH-] was held constant: Q recycling was almost reversible. Meanwhile, Qs with E(Q/Q*-) > - 100 mV demonstrated a dramatic deviation from the 'standard' behavior that was manifested by the fast decrease in R(OX) with time and non-linear dependence of even starting values of R(OX) on [Q] and [AscH-]. These deviations were caused basically by the participation of Q*- in side reactions different from (2). The above findings were confirmed by kinetic computer simulations. Some biological implications of Q-AscH- interaction were discussed.

Topics: Aerobiosis; Ascorbic Acid; Benzoquinones; Catalysis; Computer Simulation; Kinetics; Naphthoquinones; Oxidation-Reduction; Quinones; Structure-Activity Relationship

Sonolysis of argon-saturated aqueous quinone solutions resulted in an enhancement in ferricytochrome c (Cyt c) reduction. Upon addition of superoxide dismutase, Cyt c reduction was partially inhibited, thus implying a role of superoxide ion in this reduction process. Neither quinone hydrophobicity nor reduction potential exclusively controls the Cyt c reduction enhancement, although a preference for hydrophobicity versus reduction potential is noted.

Topics: Animals; Argon; Benzoquinones; Cytochrome c Group; Naphthoquinones; Oxidation-Reduction; Polarography; Quinones; Solutions; Sonication; Superoxide Dismutase; Vitamin K 3; Water

A random screening approach has identified 2-chloro-3-substituted-1,4-naphthoquinones as potent inactivators of HCMV protease. Enzyme inactivation is due to modification of Cys202. Two of the most potent compounds maintain activity against HCMV in a plaque reduction assay.

Topics: Binding Sites; Cell Line; Cysteine; Glutathione; Humans; Leukocyte Elastase; Molecular Structure; Naphthoquinones; Serine Endopeptidases; Serine Proteinase Inhibitors; Thrombin; Viral Plaque Assay

Quinones play a vital role in the processes of electron transfer in bacterial photosynthetic reaction centers. It is of interest to investigate photochemical reactions involving quinones with a view to elucidate structure-function relationships in biological processes. Resonance Raman and FTIR spectra of electrochemically generated radical anions of 2-methyl-1,4-naphthoquinone, and 2-methyl-3-phytyl-1,4-naphthoquinone, also known as Vitamin K3 and Vitamin K1, respectively, (model compound for QA in Rhodopseudomonas viridis, a bacterial photosynthetic reaction center) have been reported. The same study has also been extended to 1,4-naphthoquinone for comparison. The vibrational assignments were carried out on the basis of comparison with our earlier time resolved resonance Raman studies on photochemically generated radical anions of 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone (Balakrishnan et al., J. Phys. Chem., 100, (1996), 16472-16478). These in vitro results have been compared with the reported vibrational spectral data under in vivo conditions.

Topics: Absorption; Anions; Models, Molecular; Naphthoquinones; Nuclear Magnetic Resonance, Biomolecular; Photosynthesis; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Vitamin K 1; Vitamin K 3

Thioredoxin reductase (TrxR) catalyzes the reduction of thioredoxin (Trx) by NADPH. A unique gene organization of TrxR and Trx has been found in Mycobacterium leprae, where TrxR and Trx are encoded by a single gene and, therefore, are expressed as a fusion protein (MlTrxR-Trx). This fusion enzyme is able to catalyze the reduction of thioredoxin or 5,5'-dithiobis(2-nitrobenzoic acid) or 1, 4-naphthoquinone by NADPH, though the activity is much lower than that of Escherichia coli TrxR. It has been proposed that a large conformational change is required in catalysis of E. coli TrxR. Because the reductase portion of the enzyme from M. leprae shows significant primary structure similarity with E. coli TrxR, it is possible that MlTrxR-Trx may require a similar conformational change and that the change in conformation may be affected by the tethered Trx. The reductase has been expressed without Trx attached (MlTrxR). As reported here, comparison of the steady-state and pre-steady-state kinetics of MlTrxR-Trx with those of MlTrxR suggests that the low reductase activity of the fusion enzyme is an inherent property of the reductase, and that any steric limitation caused by the attached thioredoxin in the fusion protein makes only a minor contribution to the low activity. Titration of MlTrxR-Trx and MlTrxR with 3-aminopyridine adenine dinucleotide phosphate (AADP+), an NADP(H) analogue, results in only slight quenching of FAD fluorescence, suggesting an enzyme conformation in which the binding site of AADP+ is not close to the FAD, as in one of the conformations of E. coli TrxR.

Topics: Adenine Nucleotides; Alkylation; Deuterium; Dithionite; Dithionitrobenzoic Acid; Escherichia coli; Hydrogen; Hydrogen-Ion Concentration; Kinetics; Mycobacterium leprae; NADP; Naphthoquinones; Oxidation-Reduction; Protons; Recombinant Fusion Proteins; Solvents; Thioredoxin-Disulfide Reductase; Thioredoxins; Titrimetry

Lipoamide dehydrogenase was purified around 22-fold relative to the crude extracts of Streptomyces seoulensis with an overall yield of 9. 5%. The enzyme was composed of two identical subunits with a molecular mass of 54 kDa and contained 1 mol of FAD per mol of subunit. The absorption spectra of the enzyme revealed the absorption maxima of flavoprotein at 272, 349, and 457 nm. Catalytically active two-electron reduced lipoamide dehydrogenase was produced by anaerobic reduction with one equivalent of NADH. Addition of excess amount of NADH led to the four-electron reduced lipoamide dehydrogenase. The reaction of the enzyme in the reduction reaction of lipoamide or lipoic acid could be explained by a ping-pong mechanism like many other lipoamide dehydrogenases reported earlier. The enzyme also catalysed the reduction of various quinone compounds with NADH as electron donor via a ping-pong mechanism. The enzyme can catalyse a single electron transfer in case of quinone-reducing process, evidenced by the production of 1, 4-naphthosemiquinone radical anion. The quinone-reducing activity of the enzyme was dramatically inhibited by NAD+, indicating the involvement of four-electron reduced form. The structural gene for the enzyme was cloned using a DNA fragment PCR-amplified with the primers designed from N-terminal and internal amino acid sequences. The deduced amino acid sequence shared striking similarity with those of lipoamide dehydrogenases from prokaryotes and eukaryotes. The gene was named lpd. All tested Streptomyces contained one homologue of the lpd gene, which is consistent with the fact that most organisms contain only one lipoamide dehydrogenase.

Topics: Amino Acid Sequence; Bacterial Proteins; Base Sequence; Cloning, Molecular; Dihydrolipoamide Dehydrogenase; Electron Spin Resonance Spectroscopy; Kinetics; Molecular Sequence Data; NAD; Naphthoquinones; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Spectrometry, Fluorescence; Spectrophotometry; Streptomyces; Substrate Specificity

The mitochondrial permeability pore is subject to regulation by a thiol-dependent voltage sensor (Petronilli, V., Costantini, P., Scorrano, L., Colonna, R., Passamonti, S., and Bernardi, P., J. Biol. Chem. 269, 16638-16642, 1994); thiol oxidation increases the gating potential, which increases the probability of pore opening. Monofunctional sulfhydryl-alkylating agents, by preventing formation of the disulfide, inhibit oxidant-induced changes in the gating potential. According to this paradigm, redox-cycling and arylating quinones should have distinct and opposing effects on the voltage-dependent permeabilization of mitochondrial membranes. Freshly isolated rat liver mitochondria were susceptible to a calcium-dependent permeability transition characterized by osmotic swelling and membrane depolarization, both of which were inhibited by Cyclosporine A. 1,4-Naphthoquinone, 2-methyl-1,4-naphthoquinone (menadione), and 2,3-dimethoxy-1,4-naphthoquinone elicited an increase in gating potential of the permeability pore that was prevented by Cyclosporine A or N-ethylmaleimide and reversed by dithiothreitol. Benzoquinone, on the other hand, inhibited NADH-ubiquinone oxidoreductase. Accordingly, in mitochondria energized with glutamate plus malate benzoquinone caused a direct, calcium-independent depolarization of membrane potential and mitochondrial swelling that were not inhibited by Cyclosporine A. In contrast, benzoquinone did not interfere with succinate-supported mitochondrial bioenergetics. In fact, adding benzoquinone to succinate-energized mitochondria prevented induction of the mitochondrial permeability transition by all three redox-cycling naphthoquinones. We attribute this to the electrophilic, sulfhydryl-arylating reactivity of benzoquinone. The results suggest that differences in the mechanisms by which quinones of varying chemical reactivity interfere with mitochondrial bioenergetics can be explained in terms of the distinct manner in which they react with the thiol-dependent voltage sensor of the mitochondrial permeability pore.

Topics: Animals; Benzoquinones; Energy Metabolism; Glutamic Acid; In Vitro Techniques; Indicators and Reagents; Intracellular Membranes; Ion Channels; Malates; Membrane Potentials; Membrane Proteins; Mitochondria, Liver; Mitochondrial Swelling; Naphthoquinones; Oxidation-Reduction; Permeability; Porins; Rats; Voltage-Dependent Anion Channels

The cytoprotective effect of green tea extract and its phenolic compounds against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone, lactate dehydrogenase (LDH) leakage and cell viability were both improved by the presence of the tea extract and tea polyphenols. This cytoprotective effect was related to the structure of tea polyphenols, the galloyl group of (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate being particularly effective. The production of liquid peroxidation by 1,4-naphthoquinone was not inhibited by the tea extract nor by tea polyphenol addition. After 2 h of incubation, the protein thiol concentration was reduced by 1,4-naphthoquinone, but this reduction was prevented by the tea extract and tea polyphenols. The reduction in protein thiol content of the cells closely paralleled the LDH leakage and loss of cell viability. These results suggest that the mechanism of protection by tea polyphenols against 1,4-naphthoquinone-induced toxicity to rat hepatocytes was due to the maintenance of protein thiol levels.

Topics: Animals; Cells, Cultured; Chemical and Drug Induced Liver Injury; Drug Interactions; Liver; Liver Diseases; Male; Naphthoquinones; Phenols; Plant Extracts; Polymers; Rats; Rats, Sprague-Dawley; Sulfhydryl Compounds; Tea

Nitric oxide (NO) has been postulated as a regulator of vascular reactivity, and the current study tested the hypothesis that NO-induced decreased sensitivity to vasoconstrictors persists following removal of NO. Endothelium-denuded segments of rat aorta were incubated 2-4 h at 37 degrees C with the NO donor S-nitroso-N-acetylpenicillamine (SNAP). Incubation produced rightward shifts in concentration response curves for phenylephrine [i.e., half-maximum effective concentration (EC50; in microM): control = 0.016, NO = 0.14], aluminum fluoride (i.e., EC50 in mM: control = 1.66, NO = 2.29), and KCl (i.e., EC50 in mM: control = 5.9, NO = 23.9). Similar shifts were seen for two other NO donors. The SNAP-induced shift was not attenuated by a guanylyl cyclase inhibitor, LY-83583 (10 microM) and was not mimicked by 8-bromoguanosine 3',5'-cyclic monophosphate (100 microM). It was attenuated by 1,4-naphthoquinone (50 microM), an inhibitor of endogenous mono-ADP ribosyltransferases. NO incubation increased cGMP content (4.6 +/- 0.8 vs. 1.5 +/- 0.15 pmol/mg protein), an increase unaffected by 1,4-naphthoquinone (3.3 +/- 1.0 pmol/mg protein) but prevented by LY-83583 (1.6 +/- 0.36 pmol/mg protein). ADP ribosylation of three proteins was observed in membranes from HEK 293 cells: 88,66, and 38 kDa. ADP ribosylation of the 38-kDa protein was stimulated in a concentration-dependent manner by NO but was not decreased by 1,4-naphthoquinone. In conclusion, NO produces a long-lasting inhibition of vascular contractility by both a cGMP-dependent and -independent mechanism. Based on the observations of 1,4-naphthoquinone, we conclude that the cGMP-independent mechanism is not stimulation of endogenous ADP ribosylation but some other covalent modification in the pathway that mediates contraction.

Topics: ADP Ribose Transferases; Aluminum Compounds; Aminoquinolines; Animals; Aorta; Cyclic GMP; Fluorides; Guanylate Cyclase; In Vitro Techniques; Male; Naphthoquinones; Nitric Oxide; Penicillamine; Poly(ADP-ribose) Polymerase Inhibitors; Potassium Chloride; Rats; Rats, Inbred WKY; S-Nitroso-N-Acetylpenicillamine; Time Factors; Vasoconstriction; Vasoconstrictor Agents; Vasodilator Agents

The role of mitochondrial dysfunction in the mechanisms of cell killing by quinones of differing chemical reactivities was investigated. Freshly isolated hepatocyte suspensions were exposed to 2,3-dimethoxy-1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 1,4-naphthoquinone or 1,4-benzoquinone in the presence or absence of cyclosporine A, ruthenium red, fructose or the combination of fructose plus oligomycin. All of the quinones caused concentration-dependent cell killing as assessed by the leakage of lactate dehydrogenase. However, only 2,3-dimethoxy- and 2-methyl-naphthoquinone caused a depolarization of mitochondrial membrane potential; cell killing by 1,4-naphthoquinone or 1,4-benzoquinone was not accompanied by mitochondrial depolarization. Neither cyclosporine A nor ruthenium red protected against cell killing or loss of mitochondrial membrane potential caused by any of the quinones examined. In contrast, fructose protected cells against all four quinones. For the redox cycling naphthoquinones, oligomycin reversed the protection afforded by fructose. However, the cytoprotective effect of fructose against the arylating quinones, 1,4-naphthoquinone and 1,4-benzoquinone, was not reversed by oligomycin. The results suggest that cell killing by redox cycling naphthoquinones is a manifestation of mitochondrial depolarization, not ATP depletion. In contrast, the fructose-mediated protection from arylating quinones is consistent with ATP depletion being a critical event leading to cell death. According, although a vast array of quinone compounds are known to be cytotoxic, the mechanism of cell killing by individual members of this chemical class differs and is determined primarily by the chemical reactivity of the individual quinone.

Topics: Animals; Cell Survival; Cells, Cultured; Dose-Response Relationship, Drug; Liver; Male; Membrane Potentials; Mitochondria, Liver; Naphthoquinones; Rats; Rats, Sprague-Dawley; Vitamin K 3

Naphthalene (NA) is metabolically activated to the reactive intermediates, naphthalene oxide (NO) and naphthoquinones. To investigate the role of circulating reactive metabolites in NA toxicity, the half-life of NO was examined. The in vitro half-life of NO in both whole blood and plasma was 10 min. Detectable levels of NO were seen in perfusate leaving the isolated perfused liver of B6C3F1 mice infused with 10 mumol/h NA. Identification of protein sulfhydryl adducts in NA-exposed mice (50 and 100 mg/kg, IP, 24 h) revealed a predominance of quinone adducts in liver, lung, kidney, red blood cells and brain. The epoxide adduct predominated in plasma protein. Administration of the sulfate conjugate of 1,4-dihydroxynaphthalene (NHQS) (100 mg/kg) resulted in formation of naphthoquinone protein sulfhydryl adducts in lung, liver and kidney. Administration of 1,4-naphthoquinone (NQ) (5 mg/kg) produced NQ adducts in liver, lung, kidney, plasma and brain.

Topics: Animals; Binding Sites; Brain; Half-Life; Hydroquinones; Kidney; Liver; Lung; Male; Mass Spectrometry; Mice; Naphthalenes; Naphthoquinones; Structure-Activity Relationship; Tissue Distribution

Freshly-isolated rat hepatocytes were exposed in glucose (15 mM) or fructose (5 mM) medium to menadione (2-methyl-1,4-naphthoquinone) (85 microM) or 1,4-naphthoquinone (NQ) (50 microM). Menadione and NQ are closely related quinones and have an approximately equal potential to induce redox cycling. However, NQ has a higher potential to arylate and is more toxic than menadione. During 2 hr of incubation, cell viability, thiol status, adenine nucleotide level and lactate production were determined. LDH-leakage was used as a measure of cell viability. In glucose medium, exposure of hepatocytes to menadione or NQ resulted in a faster excretion rate of oxidized glutathione as compared to those cells in fructose medium. As a result, quinone-exposed hepatocytes in fructose medium retained higher amounts of oxidized glutathione. Menadione-exposed hepatocytes in fructose medium exhibited a diminished rate of transthiolation of protein thiols with oxidized glutathione as compared to those cells in glucose medium. The adenine nucleotide level of hepatocytes in glucose medium was markedly higher than in fructose medium. This was caused by an ATP decrease in hepatocytes in fructose medium resulting in a low energy charge (E.C.) (0.6) as compared to hepatocytes in glucose medium (0.9). Only menadione caused a decrease in the E.C. in glucose medium while NQ caused a decrease of all three adenine nucleotides. In fructose medium, quinone-exposed hepatocytes showed no change in their adenine nucleotides as compared to control cells. Despite the higher oxidized glutathione content and the lower ATP level of NQ-exposed hepatocytes in fructose medium, they had a better viability than those cells in glucose medium. From our results we conclude that a high ATP content is not always beneficial for cell survival.

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Cell Survival; Cells, Cultured; Fructose; Glucose; Glutathione; Liver; Male; Naphthoquinones; Rats; Rats, Wistar; Sulfhydryl Compounds; Vitamin K

The cytotoxic events in freshly isolated rat hepatocytes following exposure over 2 h to menadione (2-methyl-1,4-naphthoquinone) and two closely related quinones, 2,3-dimethyl-1,4-naphthoquinone (DMNQ) and 1,4-naphthoquinone (NQ), were examined. These quinones differ in their arylation capacity (NQ > menadione >> DMNQ) and in their potential to induce redox cycling (NQ approximately menadione >> DMNQ) The glutathione status (reduced and oxidized glutathione) of the hepatocytes was determined using HPLC after derivatization with monobromobimane. Protein thiols were measured spectrophotometrically and the energy charge of the cells was determined with HPLC using ion pair chromatography. The leakage of lactate dehydrogenase was used as a marker for cell viability. All three quinones caused alterations of the glutathione status of the exposed cells but the effects were markedly different. Exposure to DMNQ resulted in a slow decrease of reduced glutathione and an increase of mixed disulfides. The other two quinones caused an almost complete depletion of reduced glutathione within 5 min. Hepatocytes exposed to NQ accumulated oxidized glutathione whereas menadione-exposed hepatocytes showed increased levels of mixed disulfides. We did not find any effects of DMNQ (200 microM) on protein thiols, energy charge or cell viability. There was a clear difference in the effects of menadione and NQ on protein thiols, energy charge and cell viability; exposure to NQ resulted in a more extensive decrease of protein thiols and energy charge and an earlier onset of lactate dehydrogenase leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cell Survival; Energy Metabolism; Glutathione; Homeostasis; In Vitro Techniques; Liver; Male; Naphthoquinones; Rats; Rats, Wistar; Sulfhydryl Compounds; Vitamin K

Exposure of rat hepatocytes to hydrazine, carbon tetrachloride or 1,4-naphthoquinone results in cytotoxicity determined as uptake of Trypan blue and leakage of lactate dehydrogenase (LDH). After exposure of hepatocytes to hydrazine and 1,4-naphthoquinone, ATP was also measured and was found to be depleted. Addition of the beta-amino acid taurine to the hepatocyte incubation buffer partially protects the cells against the cytotoxicity of these three different cytotoxic compounds, as indicated by Trypan blue uptake and LDH leakage. Taurine also reduces the depletion of ATP caused by 1,4-naphthoquinone but not hydrazine. It is suggested that taurine may have a cytoprotective effect in vitro and may be a useful tool for the investigation of mechanisms of cytotoxicity.

Topics: Animals; Carbon Tetrachloride; Cell Survival; Cells, Cultured; Hydrazines; L-Lactate Dehydrogenase; Liver; Male; Naphthoquinones; Rats; Rats, Sprague-Dawley; Taurine; Trypan Blue

The kinetic parameters of the redox transitions subsequent to the two-electron transfer implied in the glutathione (GSH) reductive addition to 2- and 6-hydroxymethyl-1,4-naphthoquinone bioalkylating agents were examined in terms of autoxidation, GSH consumption in the arylation reaction, oxidation of the thiol to glutathione disulfide (GSSG), and free radical formation detected by the spin-trapping electron spin resonance method. The position of the hydroxymethyl substituent in either the benzenoid or the quinonoid ring differentially influenced the initial rates of hydroquinone autoxidation as well as thiol oxidation. Thus, GSSG- and hydrogen peroxide formation during the GSH reductive addition to 6-hydroxymethyl-1,4-naphthoquinone proceeded at rates substantially higher than those observed with the 2-hydroxymethyl derivative. The distribution and concentration of molecular end products, however, was the same for both quinones, regardless of the position of the hydroxymethyl substituent. The [O2]consumed/[GSSG]formed ratio was above unity in both cases, thus indicating the occurrence of autoxidation reactions other than those involved during GSSG formation. EPR studies using the spin probe 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) suggested that the oxidation of GSH coupled to the above redox transitions involved the formation of radicals of differing structure, such as hydroxyl and thiyl radicals. These were identified as the corresponding DMPO adducts. The detection of either DMPO adduct depended on the concentration of GSH in the reaction mixture: the hydroxyl radical adduct of DMPO prevailed at low GSH concentrations, whereas the thiyl radical adduct of DMPO prevailed at high GSH concentrations. The production of the former adduct was sensitive to catalase, whereas that of the latter was sensitive to superoxide dismutase as well as to catalase. The relevance of free radical formation coupled to thiol oxidation is discussed in terms of the thermodynamic and kinetic properties of the reactions involved as well as in terms of potential implications in quinone cytotoxicity.

Topics: Alkylating Agents; Chromatography, High Pressure Liquid; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Electrons; Free Radicals; Glutathione; Hydroxides; Hydroxyl Radical; Naphthoquinones; Oxidation-Reduction; Polarography; Spectrophotometry

The effect of hydroxy substitution on 1,4-naphthoquinone toxicity to cultured rat hepatocytes was studied. Toxicity of the quinones decreased in the series 5,8-dihydroxy-1,4-naphthoquinone greater than 5-hydroxy-1,4-naphthoquinone greater than 1,4-naphthoquinone greater than 2-hydroxy-1,4-naphthoquinone, and intracellular GSSG formation decreased in the order 5,8-dihydroxy-1,4-naphthoquinone greater than 5-hydroxy-1,4-naphthoquinone much greater than 1,4-naphthoquinone much greater than 2-hydroxy-1,4-naphthoquinone. The electrophilicity of the quinones decreased in the order 1,4-naphthoquinone much greater than 5-hydroxy-1,4-naphthoquinone greater than 5,8-dihydroxy-1,4-naphthoquinone much greater than 2-hydroxy-1,4-naphthoquinone. Treatment of the hepatocytes with BSO (buthionine sulfoximine) or BCNU (1,3-bis-2-chloroethyl-1-nitrosourea) increased 5-hydroxy-1, 4-naphthoquinone and 5,8-dihydroxy-1,4-naphthoquinone toxicity, whereas neither BSO nor BCNU largely affected 1,4-naphthoquinone and 2-hydroxy-1, 4-naphthoquinone toxicity. Dicumarol increased the toxicity of 1,4-naphthoquinone dramatically and somewhat the toxicity of 2-hydroxy-1,4- naphthoquinone, whereas 5-hydroxy-1,4-naphthoquinone and 5,8-dihydroxy-1,4-naphthoquinone toxicity increased only slightly. The toxicity of 5,8-dihydroxy-1,4-naphthoquinone decreased dramatically in reduced O2 concentration, whereas 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, and 2-hydroxy-1,4-naphthoquinone toxicity was not largely affected. It was concluded that 5,8-dihydroxy-1,4-naphthoquinone toxicity is due to free radical formation, whereas the toxicity of 1,4-naphthoquinone and of 5-hydroxy-1,4-naphthoquinone also has an electrophilic addition component. The toxicity of 2-hydroxy-1,4-naphthoquinone could not be fully explained by either of these phenomena.

Topics: Animals; Buthionine Sulfoximine; Carmustine; Cell Survival; Dicumarol; Glutathione; Liver; Male; Methionine Sulfoximine; Mitochondria, Liver; Molecular Structure; Naphthoquinones; Oxidation-Reduction; Oxygen Consumption; Rats; Rats, Inbred Strains; Structure-Activity Relationship

The effect of superoxide dismutase on the autoxidation of hydro- and semi-1,4-naphthoquinones with different substitution pattern and covering a one-electron reduction potential range from -95 to -415 mV was examined. The naphthoquinone derivatives were reduced via one or two electrons by purified NADPH-cytochrome P-450 reductase or DT-diaphorase, respectively. Superoxide dismutase did not alter or slightly enhance the initial rates of enzymic reduction, whereas it affected in a different manner the following autoxidation of the semi- and hydroquinones formed. Autoxidation was assessed as NADPH oxidation in excess to the amounts required to reduce the quinone present, H2O2 formation, and the redox state of the quinones. Superoxide dismutase enhanced 2--8-fold the autoxidation of 1,4-naphthosemiquinones, following the reduction of the oxidized counterpart by NADPH-cytochrome P-450 reductase, except for the glutathionyl-substituted naphthosemiquinones, whose autoxidation was not affected by superoxide dismutase. Superoxide dismutase exerted two distinct effects on the autoxidation of naphthohydroquinones formed during DT-diaphorase catalysis: on the one hand, it enhanced slightly the autoxidation of 1,4-naphthohydroquinones with a hydroxyl substituent in the benzene ring: 5-hydroxy-1,4-naphthoquinone and the corresponding derivatives with methyl- and/or glutathionyl substituents at C2 and C3, respectively. On the other hand, superoxide dismutase inhibited the autoxidation of naphthohydroquinones that were either unsubstituted or with glutathionyl-, methyl-, methoxyl-, hydroxyl substituents (the latter in the quinoid ring). The inhibition of hydroquinone autoxidation was reflected as a decrease of NADPH oxidation, suppression of H2O2 production, and accumulation of the reduced form of the quinone. The enhancement of autoxidation of 1,4-naphthosemiquinones by superoxide dismutase has been previously rationalized in terms of the rapid removal of O2-. by the enzyme from the equilibrium of the autoxidation reaction (Q2-. + O2----Q + O2-.), thus displacing it towards the right. The superoxide dismutase-dependent inhibition of H2O2 formation as well as NADPH oxidation during the autoxidation of naphthohydroquinones--except those with a hydroxyl substituent in the benzene ring--seems to apply to those organic substrates which can break down with simultaneous formation of a semiquinone and O2-.. Inhibition of hydroquinone autoxidation by superoxide dismutase can be

Topics: Animals; Chemical Phenomena; Chemistry; Chromatography, High Pressure Liquid; Kinetics; Molecular Structure; NAD(P)H Dehydrogenase (Quinone); NADP; NADPH-Ferrihemoprotein Reductase; Naphthoquinones; Oxidation-Reduction; Quinone Reductases; Rats; Superoxide Dismutase; Thermodynamics

Naphthalene-induced pulmonary and renal toxicity and polycyclic aromatic hydrocarbon-induced carcinogenesis are known to be mediated by their reactive metabolites. Subchronic exposure (90 d) of mice to naphthalene does not alter humoral and cellular-mediated immune responses, whereas polycyclic aromatic hydrocarbons, such as benzo[a]pyrene and 7,12-dimethylbenzanthracene, are known to be immunosuppressive. To understand these differences, the antibody-forming cell (AFC) responses of splenocyte cultures exposed to naphthalene (2, 20, and 200 microM) were evaluated. At these concentrations, the antibody-forming cell response to sheep red blood cells (RBC) was not affected. To determine if reactive metabolites of naphthalene were immunosuppressive, splenocytes were exposed to naphthalene metabolites by direct addition or through the use of a metabolic activation system. The addition of 1-naphthol (70 and 200 microM) and 1,4-naphthoquinone (2, 7, and 20 microM) resulted in a decreased antibody-forming cell response. Suppression of AFC responses was also obtained by culturing splenocytes with liver S9 and naphthalene. Since splenic metabolism of naphthalene to nonimmunosuppressive metabolites may account for the absence of immunotoxicity, the types of naphthalene metabolites generated by splenic microsomes were determined. It was observed that splenic microsomes were unable to generate any detectable naphthalene metabolites, whereas liver microsomes were able to generate both 1,2-naphthalene diol and 1-naphthol. Thus, the absence of an immunosuppressive effect by naphthalene exposure may be related to the inability of splenocytes to metabolize naphthalene. Moreover, the concentration of naphthalene metabolites generated within the liver that may diffuse to the spleen may be inadequate to produce immunotoxicity.

Topics: Animals; Antibody Formation; Antibody-Producing Cells; Benzo(a)pyrene; Cell Survival; Female; Liver; Mice; NADP; Naphthalenes; Naphthols; Naphthoquinones; Spleen

The effect on red blood cell metabolism of a series of substituted 1,4-naphthoquinones has been investigated. 2-Methoxy-1,4-naphthoquinone was found to be a potent oxidative compound, generating hydrogen peroxide in erythrocytes and causing both methemoglobin formation and glutathione depletion in the absence of glucose. Flux of glucose through both glycolysis and the hexose monophosphate shunt was stimulated. 2-Hydroxy- and 2,3-dihydroxy-1,4-naphthoquinone were less oxidative. Both compounds caused oxidation of glutathione and formation of hydrogen peroxide with corresponding stimulation of the hexose monophosphate shunt, but did not cause methemoglobin formation. 2-Hydroxy-3-alkyl-1,4-naphthoquinones were not oxidative but did increase the flux of glucose through glycolysis, possibly reflecting membranal damage. The in vitro oxidative effects of these substances do not correlate with their hemolytic activity in rats, indicating that factors other than oxidative damage are important in mediating the in vivo toxicity of these substances.

Topics: Animals; Erythrocytes; Glutathione; Glycolysis; Humans; Hydrogen Peroxide; Methemoglobin; Naphthoquinones; Pentose Phosphate Pathway; Sheep; Structure-Activity Relationship

The copper-chelating thiol drug, diethyldithiocarbamate (DEDC) had previously been used to inhibit superoxide dismutase (SOD) and enhance oxidative stress mediated cytotoxicity. Using isolated rat hepatocytes, it was confirmed that DEDC enhances oxidative stress cytotoxicity induced by 1,4-naphthoquinone (1,4-NQ) and 1,4-naphthoquinone-2-sulphonate (1,4-NQ-2S). However, equimolar concentrations of DEDC also enhances cytotoxicity induced by benzoquinone, previously shown to cause cytotoxicity as a result of alkylation and not oxidative stress. Higher DEDC concentrations on the other hand protected against benzoquinone-induced cytotoxicity. Finally, the susceptibility of hepatocytes to quinone mediated oxidative stress cytotoxicity was not enhanced if the DEDC was removed before incubating the hepatocytes with naphthoquinone or benzoquinone. Enhanced oxidative stress cytotoxicity was only observed if the DEDC was present when hepatocytes were treated with quinones. It was concluded that DEDC forms conjugates with quinones which undergo futile redox cycling in the hepatocyte and form H2O2 as well as increase the susceptibility of hepatocytes to H2O2.

Topics: Animals; Cell Survival; Ditiocarb; Glutathione; In Vitro Techniques; Liver; Male; Naphthoquinones; Oxidation-Reduction; Quinones; Rats; Rats, Inbred Strains; Superoxide Dismutase

The effect of several structurally related 1,4-benzoquinones (BQ) and 1,4-naphthoquinones (NQ) on the activity of rat hepatic glutathione S-transferases (GST) was studied. For the 1,4-benzoquinones, the extent of inhibition increased with an increasing number of halogen substituents. Neither the type of halogen nor the position of chlorine-atoms was of major importance. Similarly, 2,3-dichloro-NQ demonstrated a considerably higher inhibitory activity than 5-hydroxy-NQ. 2-Methyl derivatives of NQ did not inhibit GST activity at all. The irreversible nature of the inhibition was shown both by the time-course of the inhibition as well as by the fact that removal of the inhibitor by ultrafiltration did not restore the enzymatic activity. Incubation of quinones and enzyme in the presence of the competitive inhibitor S-hexyl-glutathione, slowed the inhibition considerably, indicating an involvement of the active site. Isoenzyme 3-3 was found to be most sensitive towards the whole series of inhibitors, whereas the activity of isoenzyme 2-2 was least affected in all cases. The inhibition by quinones is probably mainly due to covalent modification of a specific cysteine residue in or near the active site. The differential sensitivities of individual isoenzymes indicates that this residue is more accessible and/or easier modified in isoenzyme 3-3 than in any of the other isoenzymes tested. The findings suggest that quinones form a class of compounds from which a selective in vivo inhibitor of the GST might be developed.

Topics: Animals; Benzoquinones; Glutathione; Glutathione Transferase; Isoenzymes; Liver; Molecular Structure; Naphthoquinones; Quinones; Rats; Structure-Activity Relationship

The nucleophilic addition of GSH to quinonoid compounds, characterized as a 1,4-reductive addition of the Michael type, was studied with p-benzoquinone- and 1,4-naphthoquinone epoxides with different degree of methyl substitution. Identification and evaluation of molecular products from the above reaction were assessed by h.p.l.c. with either reductive or oxidative electrochemical detection, based on the redox properties retained in the molecular products formed. It was found that the degree of methyl substitution of the quinone epoxide, from either the 1,4-naphthoquinone- or p-benzoquinone epoxide series, determined their rate of reaction with GSH. The reductive addition implied the rearrangement of the quinone structure with opening of the epoxide ring yielding as the primary product a hydroxy-glutathionyl substituted adduct of either p-benzohydroquinone or 1,4-naphthohydroquinone. The primary product undergoes elimination reactions and redox transitions which bring about a number of secondary molecular products. The distribution pattern of the latter depends on the degree of methyl substitution of the quinone epoxide studied and on the concentration of O2 in the solution. The occurrence of the hydroxy-substituent in position alpha, adjacent to the carbonyl group, enhances the autoxidation properties of the compound resulting in an augmented O2 consumption and H2O2 production. Therefore, it could be expected that the chemical reactivity of the products originating from the thiol-mediated nucleophilic addition to quinone epoxides would be of toxicological interest.

Topics: Benzoquinones; Chemical Phenomena; Chemistry; Chromatography, High Pressure Liquid; Epoxy Compounds; Ethers, Cyclic; Free Radicals; Glutathione; Hydrogen Peroxide; Kinetics; Naphthoquinones; Oxidation-Reduction; Oxygen; Quinones; Vitamin K

1,4-Benzoquinone is cytotoxic in V79 Chinese hamster cells and induces gene mutations and micronuclei. The cell-damaging effects of quinones are usually attributed to thiol depletion, oxidation of NAD(P)H, and redox-cycling involving the formation of semiquinone radicals and reactive oxygen species. To elucidate the role of these mechanisms in the genotoxicity of 1,4-benzoquinone, we measured various genotoxic effects, cytotoxicity, and the levels of glutathione, NADPH, NADH, and their oxidized forms all in the same experiment. 1,4-Naphthoquinone, which does not induce gene mutations in V79 cells, was investigated for comparative reasons. The quinones had a similar effect on the levels of cofactors. Total glutathione was depleted, but levels of oxidized glutathione were slightly increased. The levels of NADPH and NADH were reduced at high concentrations of the quinones with a simultaneous increase in the levels of NADP+ and NAD+. Both compounds induced micronuclei, but neither increased the frequency of sister chromatid exchange. Only 1,4-benzoquinone induced gene mutations. This effect was observed at low concentrations, where none of the other parameters studied was affected. When the cells were depleted of glutathione prior to treatment with the quinones, the induction of gene mutations and micronuclei remained virtually unchanged. We conclude that a) induction of micronuclei and glutathione depletion by the two quinones are not linked causally, b) 1,4-benzoquinone induces gene mutations by a mechanism different from oxidative stress and glutathione depletion, and c) glutathione does not fully protect the cells against the genotoxicity of quinones.

Topics: Animals; Benzoquinones; Cell Line; Cell Survival; Glutathione; Mutagenicity Tests; Mutagens; NAD; NADP; Naphthoquinones; Oxidation-Reduction; Quinones

Pseudomonas putida J1 and J2, enriched from soil with juglone, are capable of a total degradation of 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, and 2-chloro-1,4-naphthoquinone. Naphthazerin and plumbagin are only converted into the hydroxyderivatives 2-hydroxynaphthazerin and 3-hydroxyplumbagin, respectively, whereas 2-amino-1,4-naphthoquinone is not attacked at all. The degradation of 1,4-naphthoquinone begins with a hydroxylation of the quinoid ring, yielding 2-hydroxy-1,4-naphthoquinone (lawsone). Lawsone is reduced to 1,2,4-trihydroxynaphthalene with consumption of NADH. The fission product of the quinol could not be detected by direct means because of its instability. However, the presence of 2-chromonecarboxylic acid, a secondary product of lawsone degradation, leads to the conclusion, that the cleavage of the quinol takes place in the meta-position. The resulting ring fission product is converted into salicylic acid by removal of the side chain, presumably as pyruvate. Further degradation of salicyclic acid leads to the formation of catechol, which is then cleaved in the ortho-position and then metabolized via the 3-oxoadipate pathway. The initial steps in the degradation of 2-chloro-1,4-naphthoquinone, namely, the hydroxylation of the quinone to 2-chloro-3-hydroxy-1,4-naphthoquinone, followed by the elimination of the chlorine substituent lead to lawsone, which is further degraded through the pathway described. The degradation steps could be verified by the accumulation products of mutant strains blocked in different steps of lawsone metabolism. Generation of mutants was carried out by chemical and by transposon mutagenesis. The regulation of the first steps of the pathway catalysed by juglone hydroxylase and lawsone reductase, was investigated by induction experiments.

Topics: Biotransformation; Chromatography, Thin Layer; Kinetics; Mutation; Naphthoquinones; Pseudomonas; Species Specificity; Structure-Activity Relationship

Several quinoid compounds mediated the reduction of ferrylmyoglobin (MbIV) to metmyoglobin (MbIII). The efficiency of the MbIV reduction to MbIII was accomplished by the quinones in the following order: p-benzoquinone greater than 1,4-naphthoquinone greater than 2-OH-1,4-naphthoquinone greater than 2,3-epoxy-1,4-naphthoquinone. The quinone-mediated reduction of MbIV to MbIII had the following characteristics: (a) it was stoichiometrically--rather than catalytically--related to the number of cycles of the MbIV----MbIII transition involving the reduction of H2O2. (b) It proceeded with similar efficiencies under aerobic and anaerobic conditions. (c) It did not require the free radical form of MbIV(.MbIV), thus excluding a two-electron oxidation of the quinone. (d) the nucleophilic addition of--NH2 groups of the apoprotein on the quinone seemed not to be involved through an alternative pathway in the reduction of MbIV, especially since 2-OH-1,4-naphthoquinone, a compound which cannot undergo nucleophilic addition, also facilitated the reduction of the ferryl compound. (e) No two-electron oxidation products of the unsubstituted quinones, such as quinone epoxides, were detected in the spent reaction mixture analyzed by HPLC with electrochemical detection. On the basis of these observations, it is suggested that the reduction of MbIV to MbIII by the above quinonoid compounds is a one-electron transfer process, with electron abstraction being probably accomplished at some site in the benzo ring of the quinone.

Topics: Benzoquinones; Chemical Phenomena; Chemistry; Chromatography, High Pressure Liquid; Hemeproteins; Hydrogen Peroxide; Kinetics; Metmyoglobin; Naphthoquinones; Oxidation-Reduction; Quinones; Spectrophotometry

Phenol and 1-naphthol, products of benzene and naphthalene biotransformation, are metabolized during O2- generation by xanthine oxidase/hypoxanthine and phorbol myristate acetate (PMA)-stimulated human neutrophils. The addition of 1-naphthol to xanthine oxidase/hypoxanthine incubations resulted in the formation of 1,4-naphthoquinone (1,4-NQ) whereas phenol addition yielded only small quantities of hydroquinone, catechol and a unidentified reducible product but not 1,4-benzoquinone. This formation of 1,4-NQ was dependent upon hypoxanthine, xanthine oxidase, and 1-naphthol and was inhibited by the addition of superoxide dismutase (SOD) demonstrating that the conversion was O2-mediated. During O2- generation by PMA-stimulated neutrophils, the addition of phenol interfered with luminol-dependent chemiluminescence and resulted in covalent binding of phenol to protein. Protein binding was 80% inhibited by the addition of azide or catalase to the incubations indicating that bioactivation was peroxidase-mediated. In contrast, the addition of 1-naphthol to PMA-stimulated neutrophils interfered with superoxide-dependent cytochrome c reduction as well as luminol-dependent chemiluminescence and also resulted in protein binding. Protein binding was only partially inhibited by azide or catalase. The addition of SOD in combination with catalase resulted in a significantly greater inhibition of binding when compared to that of catalase alone. The results of these experiments indicate that phenol and 1-naphthol are converted to reactive metabolites during superoxide generating conditions but by different mechanisms. The formation of reactive metabolites from phenol was almost exclusively peroxidase-mediated whereas the bioactivation of 1-naphthol could occur by two different mechanisms, a peroxidase-dependent and a direct superoxide-dependent mechanism.

Topics: Benzoquinones; Biotransformation; Blood Proteins; Chromatography, High Pressure Liquid; Humans; Hypoxanthine; Hypoxanthines; Luminescent Measurements; Naphthols; Naphthoquinones; Neutrophils; Phenol; Phenols; Quinones; Superoxide Dismutase; Superoxides; Tetradecanoylphorbol Acetate; Xanthine Oxidase

The nonenzymatic reaction of the cytotoxic compounds menadione (2-methyl-1,4-naphthoquinone) and 1,4-naphthoquinone (a reactive metabolite of 1-naphthol) with reducing agents such as NADPH and glutathione led to the formation of semiquinone-free radicals, which were detected with electron spin resonance spectroscopy. In the presence of glutathione as a reducing agent, menadione and 1,4-naphthoquinone underwent net one-electron reduction and conjugation with glutathione. At higher concentrations of glutathione, 1,4-naphthoquinone formed the semiquinones of both the monoconjugate and the diconjugate. The naphthoquinone-glutathione conjugates should redox cycle in a manner already known for the menadione conjugate. The semiquinone intermediates could be detected only under a nitrogen atmosphere and are probably the primary oxygen-reactive species responsible for the redox cycling of menadione- and naphthoquinone-glutathione conjugates.

Topics: Benzoquinones; Electron Spin Resonance Spectroscopy; Glutathione; NADP; Naphthoquinones; Oxidation-Reduction; Quinones; Vitamin K

Levels of glutathione (GSH) in tumour tissue may be important in determining the clinical response to certain anticancer agents. Recent reports have suggested that D,L-buthionine-S,R-sulphoximine (BSO), a specific inhibitor of GSH synthesis, may be used to deplete tumour cell GSH and thus increase the therapeutic ratio of these agents. We have previously shown that 1-naphthol is a potential antitumour agent, and that its possible metabolite 1,4-naphthoquinone is thiol reactive and capable of redox cycling. It was therefore of interest to investigate the effect of pretreatment with BSO, on the toxicity of these agents, to tumour cells. For comparison we included three other cytotoxic agents, melphalan, helenalin and menadione, the toxicities of which are reported to be modulated by intracellular GSH. Depletion of GSH using BSO did not effect the toxicity of 1-naphthol, or 1,4-NQ but did produce slight potentiation of the cytotoxicities of menadione, helanalin and melphalan. The lack of effect of BSO on 1-naphthol and 1,4-NQ is not easily explained but if one also considers the modest potentiation of cytotoxicity+ achieved with the other agents studied, the potential use of BSO in combined chemotherapy is at best rather modest.

Topics: Antimetabolites; Antineoplastic Agents, Phytogenic; Buthionine Sulfoximine; Cell Line; Cell Survival; Colonic Neoplasms; Drug Evaluation, Preclinical; Glutathione; Humans; Melphalan; Methionine Sulfoximine; Naphthols; Naphthoquinones; Sesquiterpenes; Sesquiterpenes, Guaiane; Vitamin K

Using ESR spectroscopy, we show that benzoquinone, 1,4-naphthoquinone and 5-hydroxy-1,4-naphthoquinone react readily with thiol containing compounds, such as glutathione, to form their respective semiquinone anion radicals. These quinones react similarly, but less readily, with the amino group of amino acids. The therapeutic or toxicological significance of the formation of semiquinone anion radicals from the reaction of quinones with nucleophiles, such as thiols and amines, remains to be assessed.

Topics: Amino Acids; Benzoquinones; Chemical Phenomena; Chemistry; Electron Spin Resonance Spectroscopy; Glutathione; Naphthoquinones; Quinones

Topics: Animals; Carbon Radioisotopes; Glutathione; Kinetics; Magnetic Resonance Spectroscopy; Male; Mass Spectrometry; Microsomes, Liver; Naphthols; Naphthoquinones; Rats; Rats, Inbred Strains

The ability of an anti-sickling drug lawsone, 2-OH-1,4-naphthoquinone, and two related compounds to inhibit the haematoporphyrin-sensitised photohaemolysis of normal and sickle cell erythrocytes has been investigated. The compounds appear to protect the erythrocyte membranes by reaction with transient oxidative species. Differential effects between normal and sickle cells are shown and these are attributed to the different membrane composition of irreversibly sickled erythrocytes. This report describes a possible basis for the decreased formation of irreversibly sickled cells in the presence of lawsone.

Topics: Erythrocyte Membrane; Hematoporphyrins; Hemolysis; Humans; Naphthoquinones; Photochemistry

From humus obtained from Stuttgart, a bacterium was isolated with lawsone (2-hydroxy-1,4-naphthoquinone) as selective source of carbon. This bacterium is capable of utilizing lawsone as sole source of carbon and energy. Morphological and physiological characteristics of the bacterium were examined and it was identified as a strain of Pseudomonas putida. The organism is referred to as Pseudomonas putida L2. The degradation of lawsone by Pseudomonas putida L2 was investigated. Salicylic acid and catechol were isolated and identified as metabolites. In lawsone-induced cells of Pseudomonas putida L2, salicylic acid is converted to catechol by salicylate 1-monooxygenase. Catechol 1,2-dioxygenase catalyses ortho-fission of catechol which is then metabolized via the beta-ketoadipate pathway. Formation of cis,cis-muconate and beta-ketoadipate was demonstrated by enzyme assays. Salicylate 1-monooxygenase and catechol 1,2-dioxygenase are induced sequentially. The enzymes of the beta-ketoadipate pathway are also inducible. Naphthoquinone hydroxylase, however, was demonstrated in induced and non-induced cells. This constitutive enzyme enables Pseudomonas putida L2 to degrade various 1,4-naphthoquinones in experiments with resting cells.

Topics: Biotransformation; Cell-Free System; Chromatography, Thin Layer; Mixed Function Oxygenases; Naphthoquinones; Pseudomonas; Spectrophotometry, Ultraviolet

The hepatic microsomal metabolism of 1-naphthol, 1,2- and 1,4-naphthoquinone has been shown to generate active oxygen species by using electron spin resonance spin-trapping techniques. 1-Naphthol, in the presence of NADPH, and 1,2- and 1,4-naphthoquinone, with either NADH or NADPH, caused a stimulation in both the rate of microsomal oxygen consumption and the formation of superoxide spin adduct, 5,5-dimethyl-2-hydroxyperoxypyrrolidino-1-oxyl (DMPO-OOH). Superoxide dismutase, but not catalase, prevented the formation of this spin adduct, further supporting the suggestion that the superoxide free radical was the major oxy-radical formed during the microsomal metabolism of 1-naphthol and the naphthoquinones. These results are compatible with the suggestion that 1-naphthol may exert its toxicity to isolated hepatocytes and other cellular systems by metabolism to naphthoquinones followed by their redox cycling with concomittant generation of active oxygen species in particular superoxide free radicals.

Topics: Animals; Electron Spin Resonance Spectroscopy; In Vitro Techniques; Male; Microsomes, Liver; NAD; Naphthols; Naphthoquinones; Oxygen Consumption; Rats; Rats, Inbred Strains; Superoxides

1-Naphthol was metabolized by rat liver microsomes, in the presence of an NADPH-generating system, both to methanol-soluble metabolites including 1,4-naphthoquinone and an uncharacterized product(s) (X) and also to covalently bound products. NADH was much less effective as an electron donor than NADPH. Metyrapone, SKF 525-A and carbon monoxide all inhibited the metabolism of 1-naphthol to 1,4-naphthoquinone and to covalently bound products suggesting the involvement of cytochrome P-450 in at least one step in the metabolic activation of 1-naphthol to reactive products. Ethylene diamine, which reacts selectively with 1,2-naphthoquinone but not 1,4-naphthoquinone, did not affect the covalent binding whereas glutathione, which reacts with both naphthoquinones, caused an almost total inhibition of covalent binding. These and other results suggested that 1,4-naphthoquinone, or a metabolite derived from it, was responsible for most of the covalent binding observed and that little if any of the binding was due to 1,2-naphthoquinone.

Topics: Animals; Ascorbic Acid; Biotransformation; Cytochrome P-450 Enzyme System; Ethylenediamines; Glutathione; In Vitro Techniques; Male; Microsomes, Liver; Naphthols; Naphthoquinones; Rats; Rats, Inbred Strains; Superoxide Dismutase

First and second half-wave reduction potentials of 11 1,4-naphthoquinones and 42 9,10-anthraquinones have been measured for solutions in dimethylformamide. The presence of hydroxy groups at the 5- and 8-positions of the 1,4-naphthoquinone nucleus, and at the 1-, 4-, 5- and 8-positions of the 9,10-anthraquinone (the alpha-positions) markedly raises both reduction potentials. Measurements on the corresponding methoxy- and acetoxyquinones indicate that internal hydrogen bonding in the alpha-hydroxyquinones makes a major contribution to stabilisation of the semiquinone, probably as a result of increased delocalisation due to exchange of the hydroxy hydrogen between the two neighbouring oxygen atoms. The bearing of this phenomenon on the mechanism of action of anthracycline antitumour quinones is discussed, and the stabilising effect on the semiquinone of hydroxy groups at the 1- and 5-positions of the 9,10-anthraquinone nucleus is highlighted.

Topics: Anthraquinones; Antineoplastic Agents; Chemical Phenomena; Chemistry; Dimethylformamide; Hydrogen Bonding; Naphthoquinones; Oxidation-Reduction; Solutions; Structure-Activity Relationship

Twelve 1,4-naphthoquinones have been tested against the ascitic form of sarcoma 180 in Swiss mice. Statistical analysis shows that the most important molecular parameter determining their effectiveness in prolonging the life of mice bearing this tumor is their redox potentials. Although the toxicities of the compounds are also related to the redox potentials in the same way, the therapeutic indexes can be increased by adding substituents of greater lipophilicity. The naphthoquinones differ greatly in antitumor activities and may inhibit the growth of malignant cells by different mechanisms.

Topics: Animals; Lethal Dose 50; Magnetic Resonance Spectroscopy; Mathematics; Mice; Naphthoquinones; Sarcoma 180; Structure-Activity Relationship

Three strains of Succinivibrio dextrinosolvens isolated from the rumen of cattle or sheep under diverse conditions grew well in a minimal medium containing glucose, minerals, cysteine, methionine, leucine, serine, ammonia, 1,4-naphthoquinone, p-aminobenzoic acid, and bicarbonate-carbonic acid buffer, pH 6.7. When menadione or vitamin K5 was substituted for 1,4-naphthoquinone, the growth rate was somewhat depressed. Growth was poor with vitamin K1 and ammonia, further addition of the amino acids aspartic acid, arginine, histidine, and tryptophan was necessary for good growth of type strain 24, but the other two strains grew well only in media containing ammonia. Strains C18 and 22B produced urease and grew well when ammonia replaced urea. When urea replaced ammonia, strain 24 grew poorly and urease activity could not be detected. Strain 24 required no B-vitamins, but the other two strains were stimulated by p-aminobenzoic acid. The methionine requirement was not placed by vitamin B12, betaine, or homocysteine. Cysteine was replaced by sulfide in strain 24 but less well in the other two strains. Very poor growth was obtained when sulfate replaced cysteine. The half-saturation constant for ammonia during growth of S. dextrinosolvens is more than 500 microM, a much higher value than that of many rumen bacteria.

Topics: Animals; Cattle; Gram-Negative Anaerobic Bacteria; Kinetics; Naphthoquinones; Nitrogen; Rumen; Vitamin K

When associated with a planar phospholipid membrane, chromatophores isolated from photosynthetic sulfur bacteria Chromatium minutissimum, Ectothiorhodospira shaposhnikovii, and Chlorobium limicola f. thiosulfatophilum were shown to generate a light-induced transmembrane electric potential difference measured by a direct method using macroelectrodes and a voltmeter. The maximal photoelectric responses were observed upon the addition of 1,4-naphthoquinone in combination with phenazine methosulfate (or TMPD) and ascorbate. The photoeffects were inhibited by CCCP and gramicidin. The data demonstrate that similar mechanisms of photoelectric generation function in membranes of the different bacteria studied.

Topics: Ascorbic Acid; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Chlorobium; Chromatium; Ectothiorhodospira; Gramicidin; Light; Membrane Potentials; Methylphenazonium Methosulfate; Naphthoquinones

Topics: Chemical Phenomena; Chemistry; Chromatography; Mercaptoethanol; Naphthoquinones; Research; Retinoids; Sulfhydryl Compounds; Sulfides; Vitamin K

Topics: Chromatography; Enterococcus faecalis; Escherichia coli; Naphthoquinones; Research; Spectrophotometry

Topics: Amebicides; Analgesics; Anilides; Anti-Infective Agents; Chemistry, Pharmaceutical; Hydroquinones; Naphthoquinones; Research

Topics: Chemical Phenomena; Chemistry; Dactinomycin; DNA; Models, Theoretical; Naphthoquinones; Nucleosides; Research; Spectrophotometry

Topics: Dinitrophenols; Enzyme Inhibitors; Hydroxyquinolines; Liver; Metabolism; Mitochondria; Naphthoquinones; Oxidation-Reduction; Oxides; Pharmacology; Quinolines; Rats; Research; Succinates; Succinic Acid

Topics: Antifibrinolytic Agents; Chemistry, Pharmaceutical; Naphthoquinones; Pharmacy; Research; Retinoids; Vitamin K; Vitamin K 3

Topics: Animals; Fibrinolytic Agents; Metabolism; Mitochondria; Naphthoquinones; Oxidative Phosphorylation; Vitamin K; Vitamin K 1

Topics: Analgesics; Analgesics, Non-Narcotic; Antipyretics; Naphthoquinones

Topics: Antifungal Agents; Naphthoquinones

Topics: Naphthoquinones

Topics: Antimalarials; Naphthoquinones; Polyenes

Topics: Antimalarials; Naphthoquinones

Topics: Hydrazones; Naphthoquinones; Research

Topics: Blood Coagulation; Hemorrhage; Humans; Naphthoquinones

Topics: Hemorrhage; Humans; Naphthoquinones