naphthoquinones and 1-2-naphthoquinone

Air pollutants such as diesel exhaust particles (DEP) are thought to cause pulmonary diseases such as asthma as a result of oxidative stress. While DEP contain a large number of polycyclic aromatic hydrocarbons, we have focused on 9,10-phenanthrenequinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ) because of their chemical properties based on their oxidative and chemical modification capabilities. We have found that 9,10-PQ interacts with electron donors such as NADPH (in the presence of enzymes) and dithiols, resulting in generation of excess reactive oxygen species (ROS) through redox cycling. We have also shown that 1,2-NQ is able to modify protein thiols, leading to protein adducts associated with activation of redox signal transduction pathways at lower concentrations and toxicity at higher concentrations. In this review, we briefly introduce our findings from the last two decades.

Topics: Air Pollutants; Antioxidant Response Elements; Asthma; NADP; Naphthoquinones; Oxidation-Reduction; Oxidative Stress; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Reactive Oxygen Species; Signal Transduction; Sulfhydryl Compounds; Vehicle Emissions

Prolonged exposure of humans to ambient particulate matter such as diesel exhaust particles (DEP) induces a variety of adverse health effects including cardiovascular diseases, asthma and cancer. Polycyclic aromatic hydrocarbons (PAHs) and their derivatives in DEP are thought to be potential candidates for the deleterious effects of DEP. We have identified 1,2-naphthoquinone (1,2-NQ) as a novel PAH quinone that contaminates DEP. Because 1,2-NQ is covalently bound to macromolecules through reactive thiols (thiolate ions), our rationale was that cellular proteins modified by 1,2-NQ seem to act as a redox-sensor and thus the interaction of thiol proteins with 1,2-NQ may disrupt their functions. To address our hypothesis, we prepared specific antibody against 1,2-NQ bound to proteins. In this review, we introduce an inhibitor of kappaB kinasebeta (IKKbeta) and protein tyrosine phosphatase 1B (PTP1B) as target molecules for 1,2-NQ. Although IKKbeta activates transcription factor NF-kappaB and PTP1B negatively regulates the receptor-protein tyrosine kinase, such as epidermal growth factor receptor (EGFR) in cells, covalent modification of these proteins caused by 1,2-NQ results in inhibition of NF-kappaB activity and transactivation of EGFR.

Topics: Air Pollutants; Animals; Antibodies; ErbB Receptors; Humans; I-kappa B Kinase; Naphthoquinones; NF-kappa B; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Signal Transduction; Transcriptional Activation; Vehicle Emissions

Topics: Animals; Antineoplastic Agents; Cytosol; Electron Spin Resonance Spectroscopy; Humans; Liver Extracts; Microsomes; Molecular Structure; NADP; NADPH-Ferrihemoprotein Reductase; Naphthoquinones; Neoplasms; Oxidation-Reduction; Reactive Oxygen Species

This work describes the design, sustainable synthesis, evaluation of electrochemical and biological properties against HepG2 cell lines, and AChE enzymes of different substituted derivatives of 1,4- and 1,2-naphthoquinones (NQ). A microwave-assisted protocol was optimized with success for the synthesis of the 2-substituted-1,4-NQ series and extended to the 4-substituted-1,2-NQ family, providing an alternative and more sustainable approach to the synthesis of naphthoquinones. The electrochemical properties were studied by cyclic voltammetry, and the redox potentials related to the molecular structural characteristics and the biological properties. Compounds were tested for their potential anti-cancer activity against a hepatocellular carcinoma cell line, HepG2, using MTT assay, and 1,2-NQ derivatives were found to be more active than their 1,4-NQ homologues (

Topics: Acetylcholinesterase; Cell Line; Naphthoquinones

1,2-Naphthoquinone (2-NQ) is a nucleophile acceptor that non-selectively makes covalent bonds with cysteine residues in various cellular proteins, and is also found in diesel exhaust, an air pollutant. This molecule has rarely been considered as a pharmacophore of bioactive compounds, in contrast to 1,4-naphthoquinone. We herein designed and synthesized a compound named N-(7,8-dioxo-7,8-dihydronaphthalen-1-yl)-2-methoxybenzamide (MBNQ), in which 2-NQ was hybridized with the nuclear factor-κB (NF-κB) inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) as a nucleophile acceptor. Although 50 µM MBNQ did not inhibit NF-κB signaling, 10 µM MBNQ induced cell death in the lung cancer cell line A549, which was insensitive to 2-NQ (10 µM). In contrast, MBNQ was less toxic in normal lung cells than 2-NQ. A mechanistic study showed that MBNQ mainly induced apoptosis, presumably via the activation of p38 mitogen-activated protein kinase (MAPK). Collectively, the present results demonstrate that the introduction of an appropriate substituent into 2-NQ constitutes a new biologically active entity, which will lead to the development of 2-NQ-based drugs.

Topics: Apoptosis; Humans; Lung Neoplasms; Naphthoquinones; NF-kappa B

A biomimetic alcohol dehydrogenase (ADH)-like oxidation protocol was developed using an

Topics: Alcohol Dehydrogenase; Alcohols; Aldehydes; Catalysis; Ketones; Metals; Naphthoquinones; Oxidation-Reduction

The epidermal growth factor receptor (EGFR) is the most extensively examined receptor tyrosine kinase. Several EGFR mutations and modifications have been shown to induce self-activation, which plays a central role in carcinogenesis. Recently, environmental chemicals such as PM2.5 can also activate EGFR and become risk factors for cancer. Although, the detailed mechanism remains unknown. In this study, we focused on 1,2-naphthoquinone (1,2-NQ) which is a secondary metabolite of naphthalene. Humans are exposed to 1,2-NQ through the combustion of fossil and diesel fuel and from tobacco smoke and PM2.5. Here, we demonstrate that 1,2-NQ is a novel EGFR-specific activator. We found that 1,2-NQ forms a covalent bond called N-arylation with EGFR Lys80 which is in the extracellular domain by LC-MS/MS. This modification activates the EGFR-Akt signaling pathway, which inhibits serum deprivation-induced apoptosis in A549 cells. Our study reveals an original mode of EGFR activation via covalent binding. We propose the correlation between EGFR activation without ligands and environmental pollutant-associated diseases such as cancer.

Topics: Chromatography, Liquid; Environmental Pollutants; ErbB Receptors; Humans; Naphthoquinones; Particulate Matter; Phosphorylation; Signal Transduction; Tandem Mass Spectrometry

We report the molecular design of a novel multifunctional reagent and its application for light-controlled selective protein labeling. This molecule integrates functions of protein-ligand recognition, bioconjugation, ligand cleavage, and photoactivation by merging the photochemistries of 2-nitrophenylpropyloxycarbonyl and 3-hydroxymethyl-2-naphthol with an affinity ligand and fluorescein. Highly electrophilic

Topics: Carbonic Anhydrases; Fluoresceins; Ligands; Naphthoquinones; Proteins; Tumor Necrosis Factor Ligand Superfamily Member 14

Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.

Topics: Amines; Carboxylic Acids; Catalysis; Molecular Structure; Naphthoquinones; Oxidation-Reduction

Topics: Chromatography, High Pressure Liquid; DNA Adducts; Naphthalenes; Naphthoquinones; Tandem Mass Spectrometry

Electrophiles, ubiquitously found in the environment, modify thiol groups of sensor proteins, leading to activation of redox signaling pathways such as the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor E2 related factor 2 (Nrf2) pathway. Nrf2 activation by exposure to single electrophiles has been established. However, the effect of exposure to a combination of electrophiles on Nrf2 activation has not been well evaluated. The current study examined whether combined exposure to electrophiles enhances the modification of thiol groups and Keap1/Nrf2 activation in HepG2 cells. Six electrophiles [1,2-naphthoquinone (1,2-NQ), 1,4-NQ, 1,4-benzoquinone, (E)-2-hexenal (hexenal), (E)-2-decenal, and (E)-2-butenal] were tested for S-modification of albumin in vitro and for cytotoxicity to HepG2 cells. Interestingly, a mixture of the electrophiles enhanced S-modification of albumin and cytotoxicity compared with exposure to each electrophile separately. Herein, we focused on 1,2-NQ, 1,4-NQ, and hexenal to clarify the combined effect of electrophiles on Keap1/Nrf2 activation in HepG2 cells. A concentration addition model revealed that 1,2-NQ and/or 1,4-NQ additively enhanced hexenal-mediated S-modification of GSH in vitro, whereas the cytotoxicity of hexenal was synergistically increased by simultaneous exposure of HepG2 cells to the NQs. Furthermore, an NQ cocktail (2.5 μM each) that does not activate Nrf2 enhanced hexenal-mediated Nrf2 activation. These results suggest that combined exposure to electrophiles at low concentrations induces stronger activation of redox signaling compared with exposure to each electrophile alone and worsens their cytotoxicity.

Topics: Aldehydes; Benzoquinones; Cell Survival; Dose-Response Relationship, Drug; Environmental Pollutants; Exposome; Glutathione; Hep G2 Cells; Hepatocytes; Humans; Kelch-Like ECH-Associated Protein 1; Naphthoquinones; NF-E2-Related Factor 2; Oxidation-Reduction; Serum Albumin, Human; Signal Transduction; Sulfhydryl Compounds

1,2-Naphthoquinone, a secondary metabolite of naphthalene, is an environmental pollutant found in diesel exhaust particles that displays cytotoxic and genotoxic properties. Because many quinones have been shown to act as topoisomerase II poisons, the effects of this compound on DNA cleavage mediated by human topoisomerase IIα and IIβ were examined. The compound increased the levels of double-stranded DNA breaks generated by both enzyme isoforms and did so better than a series of naphthoquinone derivatives. Furthermore, 1,2-naphthoquinone was a more efficacious poison against topoisomerase IIα than IIβ. Topoisomerase II poisons can be classified as interfacial (which interact noncovalently at the enzyme-DNA interface and increase DNA cleavage by blocking ligation) or covalent (which adduct the protein and increase DNA cleavage by closing the N-terminal gate of the enzyme). Therefore, experiments were performed to determine the mechanistic basis for the actions of 1,2-naphthoquinone. In contrast to results with etoposide (an interfacial poison), the activity of 1,2-naphthoquinone against topoisomerase IIα was abrogated in the presence of sulfhydryl and reducing agents. Moreover, the compound inhibited cleavage activity when incubated with the enzyme prior to the addition of DNA and induced virtually no cleavage with the catalytic core of the enzyme. It also induced stable covalent topoisomerase IIα-DNA cleavage complexes and was a partial inhibitor of DNA ligation. Findings were also consistent with 1,2-naphthoquinone acting as a covalent poison of topoisomerase IIβ; however, mechanistic studies with this isoform were less conclusive. Whereas the activity of 1,2-naphthoquinone was blocked in the presence of a sulfhydryl reagent, it was much less sensitive to the presence of a reducing agent. Furthermore, the reduced form of 1,2-naphthoquinone, 1,2-dihydroxynaphthalene, displayed high activity against the β isoform. Taken together, results suggest that 1,2-naphthoquinone increases topoisomerase II-mediated double-stranded DNA scission (at least in part) by acting as a covalent poison of the human type II enzymes.

Topics: DNA Cleavage; DNA Topoisomerases, Type II; Humans; Molecular Structure; Naphthoquinones; Recombinant Proteins; Topoisomerase II Inhibitors

Cataract induced by exposure to naphthalene is thought to mainly involve its metabolic activation, forming 1,2-naphthoquinone (1,2-NQ), which can modify proteins through chemical modifications. In the present study, we examined the effect of 1,2-NQ on aggregation of crystallins (cry) associated with cataract. Incubation of bovine β-cry with 1,2-NQ caused covalent modification of β-cry at Cys117 and Lys125 accompanied by reduction in its thiol content, resulting in a concentration- and temperature-dependent aggregation of β-cry, whereas only little aggregation of α-cry induced by 1,2-NQ was seen. Interestingly, addition of α-cry to the reaction mixture of β-cry and 1,2-NQ markedly blocked β-cry aggregation induced by 1,2-NQ in a concentration-dependent manner. These results suggest that β-cry predominantly undergoes chemical modification by 1,2-NQ, causing its aggregation, which is suppressed by the chaperone-like protein, α-cry. This β-cry aggregation may be, at least in part, involved in the induction of cataract caused by 1,2-NQ.

Topics: alpha-Crystallins; beta-Crystallins; Cataract; Humans; Molecular Chaperones; Naphthoquinones; Protein Aggregation, Pathological; Protein Binding

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

Quinones may be formed metabolically or abiotically from environmental pollutants and polycyclic aromatic hydrocarbons (PAHs); many are recognized as toxicological intermediates that cause a variety of deleterious cellular effects including mutagenicity. The PAH-

Topics: Deoxyguanosine; DNA; DNA Adducts; DNA Damage; Epoxy Compounds; Hydrogen Peroxide; Mutagens; Naphthoquinones; Oxidation-Reduction

A palladium-promoted oxidative annulation reaction for the synthesis of structurally diverse naphthoquinone-containing heterocycles has been developed, providing switchable access to 1,2-naphthofuroquinones and densely functionalized cyclobutene-fused 1,4-naphthofuroquinones by selective enol/enolate-directed processes. The synthetic application was extended by late-stage functionalization of an anti-HIV drug. The practical value of 1,2-naphthofuroquinone synthesis was highlighted in endothelial protective lead compound development.

Topics: Anti-HIV Agents; Apoptosis; Catalysis; Cyclization; Human Umbilical Vein Endothelial Cells; Humans; Naphthoquinones; Oxidation-Reduction; Palladium

Nocardia is a potent bacterial producer of bioactive compounds. From a culture of Nocardia beijingensis NBRC 16342, we isolated four aromatic compounds, named beijinchromes A-D (1-4). We purified them by silica gel chromatography and reverse phase HPLC, and identified their structures by NMR and high resolution (HR)-MS analyses. 1, 2, and 4 are novel 1,2,3,8-tetrasubstituted naphthalenes, and 3 is a novel 3,8-disubstituted ortho-naphthoquinone. 1 and 2 exert antioxidant activities, and 3 exhibits antibiotic activity. Remarkably, the putative biosynthetic gene clusters for 1-4 are widely distributed in 37 Nocardia species, implying their potential to produce this family of compounds and important biological functions of beijinchromes.

Topics: Molecular Structure; Naphthalenes; Naphthoquinones; Nocardia; Stereoisomerism

Several ortho-naphthoquinones (o-NQs) have trypanocidal activity against Trypanosoma cruzi, the aetiological agent of Chagas disease. Previously, we demonstrated that the aldo-keto reductase from this parasite (TcAKR) reduces o-NQs, such as β-lapachone (β-Lap) and 9,10-phenanthrenequinone (9,10-PQ), with concomitant reactive oxygen species (ROS) production. Recent characterization of TcAKR activity and expression in two T. cruzi strains, CL Brener and Nicaragua, showed that TcAKR expression is 2.2-fold higher in CL Brener than in Nicaragua. Here, we studied the trypanocidal effect and induction of several death phenotypes by β-Lap and 9,10-PQ in epimastigotes of these two strains. The CL Brener strain was more resistant to both o-NQs than Nicaragua, indicating that greater TcAKR activity is unlikely to be a major influence on o-NQ toxicity. Evaluation of changes in ROS production, mitochondrial membrane potential, phosphatidylserine exposure and monodansylcadaverine labelling evidenced that β-Lap and 9,10-PQ induce different death phenotypes depending on the combination of drug and T. cruzi strain analysed. To study whether TcAKR participates in o-NQ activation in intact parasites, β-Lap and 9,10-PQ trypanocidal effect was next evaluated in TcAKR-overexpressing parasites. Only β-Lap was more effective and induced greater ROS production in TcAKR-overexpressing epimastigotes than in controls, suggesting that TcAKR may participate in β-Lap activation.

Topics: Aldo-Keto Reductases; Animals; Chlorocebus aethiops; Membrane Potential, Mitochondrial; Naphthoquinones; Phenotype; Protozoan Proteins; Reactive Oxygen Species; Trypanocidal Agents; Trypanosoma cruzi; Vero Cells

A photo-driven bioanode was constructed using the thylakoid membrane from spinach, carbon nanotubes, and an artificial mediator. By considering a linear free-energy relationship in the electron transfer from the thylakoid membrane to the mediators, and the oxygen resistance of the reduced mediators, 1,2-naphthoquinone was selected as the most suitable mediator for the photo-driven bioanode. Water-dispersed multi-walled carbon nanotubes served as scaffolds to hold the thylakoid membrane on a porous electrode. The constructed photo-driven bioanode exhibited a photocurrent density of over 100μAcm

Topics: Bioelectric Energy Sources; Catalysis; Electrodes; Electron Transport; Light; Nanotubes, Carbon; Naphthoquinones; Spinacia oleracea; Thermodynamics; Thylakoids

Particulate matter with aerodynamic diameter ≤2.5 μm (PM

Topics: Animals; Antigen-Presenting Cells; Benzo(a)pyrene; Bone Marrow Cells; Carbon; Cytokines; Epithelial Cells; Humans; Lymphocytes; Mice; Naphthoquinones; Particulate Matter; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Respiratory Mucosa; Spleen; Vehicle Emissions

This paper provides an efficient platform to diversify the structure and pharmaceutical potentials of known natural products. Seven metabolites were obtained via the biotransformation of cryptotanshinone by the fungus Mucor rouxii AS 3.3447, and assigned as 13R-14R-hydroxy-anhydride of 16R-cryptotanshinone (1), 1S-hydroxy-anhydride of 16R-cryptotanshinone (2), 1R-hydroxy-anhydride of 16R-cryptotanshinone (3), 3S-hydroxy-epicryptoacetalide (4), 3S-hydroxy-cryptoacetalide (5), epicryptoacetalide (6), and cryptoacetalide (7). Among these compounds, 1-5 are novel. The ortho-naphthoquinone chromophore of cryptotanshinone was degraded and rearranged by M. rouxii. 1 and 3 showed good anti-influenza A virus activities with the reduced cytotoxic activities compared to the parent substrate cryptotanshinone (8). The structures of all the new compounds were determined on the basis of HRESIMS (high-resolution electrospray ionization mass spectroscopy) spectrometry, NMR (nuclear magnetic resonance) spectroscopy, ECD (electronic circular dichroism) calculations, and the CD (circular dichroism) of "in situ" method with [Rh

Topics: Antiviral Agents; Biological Products; Biotransformation; Diterpenes; Influenza A virus; Magnetic Resonance Spectroscopy; Molecular Structure; Mucor; Naphthoquinones; Phenanthrenes

Electrophiles such as methylmercury (MeHg) affect cellular functions by covalent modification with endogenous thiols. Reactive persulfide species were recently reported to mediate antioxidant responses and redox signaling because of their strong nucleophilicity. In this study, we used MeHg as an environmental electrophile and found that exposure of cells to the exogenous electrophile elevated intracellular concentrations of the endogenous electrophilic molecule 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), accompanied by depletion of reactive persulfide species and 8-SH-cGMP which is a metabolite of 8-nitro-cGMP. Exposure to MeHg also induced S-guanylation and activation of H-Ras followed by injury to cerebellar granule neurons. The electrophile-induced activation of redox signaling and the consequent cell damage were attenuated by pretreatment with a reactive persulfide species donor. In conclusion, exogenous electrophiles such as MeHg with strong electrophilicity impair the redox signaling regulatory mechanism, particularly of intracellular reactive persulfide species and therefore lead to cellular pathogenesis. Our results suggest that reactive persulfide species may be potential therapeutic targets for attenuating cell injury by electrophiles.

Topics: Animals; Antibodies; Cell Survival; Chromatography, High Pressure Liquid; Cyclic GMP; Extracellular Signal-Regulated MAP Kinases; Immunohistochemistry; Male; Methylmercury Compounds; Microscopy, Fluorescence; Naphthoquinones; Nitric Oxide; Oxidation-Reduction; PC12 Cells; ras Proteins; Rats; Rats, Wistar; Reactive Oxygen Species; Signal Transduction; Spectrometry, Mass, Electrospray Ionization; Sulfides

Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that plays a crucial role in protection of cells from electrophile-induced toxicity through up-regulating phase II detoxifying enzymes and phase III transporters. We previously reported that oxidative stress induces up-regulation of interleukin-11 (IL-11), a member of the IL-6 family that ameliorates acetaminophen-induced liver toxicity. However, a role for IL-11 in protection of cells from electrophile-induced toxicity remains unclear. Here we show that an environmental electrophile, 1,2-naphthoquinone (1,2-NQ), but not 15d-prostaglandin J

Topics: Animals; Antineoplastic Agents; Cells, Cultured; Gene Expression Regulation; HEK293 Cells; Hep G2 Cells; Humans; Hydrogen Peroxide; Interleukin-11; Interleukin-11 Receptor alpha Subunit; Intestinal Diseases; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mice, Knockout; Naphthoquinones; NF-E2-Related Factor 2; Oxidants; Oxidative Stress; Peritonitis; Prostaglandin D2; Reactive Oxygen Species

To develop in vivo monitoring meter for pH measurements is still the bottleneck for understanding the role of pH plays in the brain diseases. In this work, a selective and sensitive electrochemical pH meter was developed for real-time ratiometric monitoring of pH in different regions of rat brains upon ischemia. First, 1,2-naphthoquinone (1,2-NQ) was employed and optimized as a selective pH recognition element to establish a 2H(+)/2e(-) approach over a wide range of pH from 5.8 to 8.0. The pH meter demonstrated remarkable selectivity toward pH detection against metal ions, amino acids, reactive oxygen species, and other biological species in the brain. Meanwhile, an inner reference, 6-(ferrocenyl)hexanethiol (FcHT), was selected as a built-in correction to avoid the environmental effect through coimmobilization with 1,2-NQ. In addition, three-dimensional gold nanoleaves were electrodeposited onto the electrode surface to amplify the signal by ∼4.0-fold and the measurement was achieved down to 0.07 pH. Finally, combined with the microelectrode technique, the microelectrochemical pH meter was directly implanted into brain regions including the striatum, hippocampus, and cortex and successfully applied in real-time monitoring of pH values in these regions of brain followed by global cerebral ischemia. The results demonstrated that pH values were estimated to 7.21 ± 0.05, 7.13 ± 0.09, and 7.27 ± 0.06 in the striatum, hippocampus, and cortex in the rat brains, respectively, in normal conditions. However, pH decreased to 6.75 ± 0.07 and 6.52 ± 0.03 in the striatum and hippocampus, upon global cerebral ischemia, while a negligible pH change was obtained in the cortex.

Topics: Animals; Brain; Chemistry Techniques, Analytical; Corpus Striatum; Electrochemical Techniques; Gold; Hippocampus; Hydrogen-Ion Concentration; Male; Microelectrodes; Naphthoquinones; Rats; Rats, Wistar

A new series of ortho-naphthoquinone analogs of β-lapachone were designed, synthesized and evaluated. The biological results indicated that most of our compounds were efficient substrates for NQO1. The new scaffold with water-soluble side chain resulted in greater solubility under acidic condition compared to β-lapachone. Thus avoiding the use of hydroxylpropyl β-cyclodextrin which would finally cause the rapid drug clearance from the blood and dose-limiting toxicity in the form of hemolytic anemia. The most soluble and promising compound in this series was 2-((4-benzylpiperazin-1-yl)methyl)naphtho[2,1-d]oxazole-4,5-dione (3k), which inhibited cancer cell (NQO1-rich A549 cell line) growth at IC50 values of 4.6±1.0μmol·L(-1). Furthermore, compound 3k had in vivo antitumor activity in an A549 tumor xenografts mouse model comparable to the activity obtained with β-lapachone. The results indicated that these ortho-naphthoquinones could serve as promising leads for further optimization as novel substrates for NQO1.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Humans; Lung; Lung Neoplasms; Mice; Mice, Nude; Molecular Docking Simulation; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Solubility; Water

Rapid detection of sarcosine is a key requirement for both diagnosis and treatment of disease. We report here a simple yet sensitive colorimetric nanocomposite platform for rapid detection of sarcosine in alkaline media. The approach exploited the benefits of a rapid color-producing reaction between an organic indicator, 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS), and the analyte of sarcosine species as well as the good catalytic ability of graphene oxide (GO) to the formation of highly colored products due to its good water dispersibility, extremely large surface area and facile surface modification. As a result, a NQS functionalized GO nanocomposite through π-π stacking has been demonstrated to be useful as a highly efficient catalyst system for the selective and sensitive colorimetric determination of sarcosine by providing a nanocomposite-amplified colorimetric response. Meanwhile, the strategy offered excellent selectivity toward sarcosine species against other amino acids as well as a satisfying detection limit of 0.73 μM. More importantly, by using an electrochemical method, a credible sensing mechanism of GO nanocomposite-based colorimetric platform for a special analyte determination can be easily verified and elucidated, which also provides an attractive alternative to conventional characterization strategies.

Topics: Catalysis; Colorimetry; Cost-Benefit Analysis; Electrochemistry; Graphite; Hydrogen-Ion Concentration; Metal Nanoparticles; Nanocomposites; Nanotechnology; Naphthoquinones; Oxides; Sarcosine; Solubility; Sulfonic Acids

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

Sulfhydration by a hydrogen sulfide anion and electrophile thiolation by reactive sulfur species (RSS) such as persulfides/polysulfides (e.g., R-S-SH/R-S-Sn-H(R)) are unique reactions in electrophilic signaling. Using 1,2-dihydroxynaphthalene-4-thioacetate (1,2-NQH2-SAc) as a precursor to 1,2-dihydroxynaphthalene-4-thiol (1,2-NQH2-SH) and a generator of reactive oxygen species (ROS), we demonstrate that protein thiols can be modified by a reactive sulfenic acid to form disulfide adducts that undergo rapid cleavage in the presence of glutathione (GSH). As expected, 1,2-NQH2-SAc is rapidly hydrolyzed and partially oxidized to yield 1,2-NQ-SH, resulting in a redox cycling reaction that produces ROS through a chemical disproportionation reaction. The sulfenic acid forms of 1,2-NQ-SH and 1,2-NQH2-SH were detected by derivatization experiments with dimedone. 1,2-NQH2-SOH modified Keap1 at Cys171 to produce a Keap1-S-S-1,2-NQH2 adduct. Subsequent exposure of A431 cells to 1,2-NQ or 1,2-NQH2-SAc caused an extensive chemical modification of cellular proteins in both cases. Protein adduction by 1,2-NQ through a thio ether (C-S-C) bond slowly declined through a GSH-dependent S-transarylation reaction, whereas that originating from 1,2-NQH2-SAc through a disulfide (C-S-S-C) bond was rapidly restored to the free protein thiol in the cells. Under these conditions, 1,2-NQH2-SAc activated Nrf2 and upregulated its target genes, which were enhanced by pretreatment with buthionine sulfoximine (BSO), to deplete cellular GSH. Pretreatment of catalase conjugated with poly(ethylene glycol) suppressed Nrf2 activation by 1,2-NQH2-SAc. These results suggest that RSS-mediated reversible electrophilic signaling takes place through sulfenic acids formation under oxidative stress.

Topics: Cell Line, Tumor; Cysteine; Humans; Intracellular Signaling Peptides and Proteins; Kelch-Like ECH-Associated Protein 1; Naphthols; Naphthoquinones; NF-E2-Related Factor 2; Oxidative Stress; Signal Transduction; Sulfenic Acids; Sulfhydryl Compounds; Sulfur

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

The photophysical and photochemical reactions of β-lapachone were studied using femtosecond transient absorption, nanosecond transient absorption, and nanosecond time-resolved resonance Raman spectroscopy techniques and density functional theory calculations. In acetonitrile, β-lapachone underwent an efficient intersystem crossing to form the triplet state of β-lapachone. However, in water-rich solutions, the singlet state of β-lapachone was predominantly quenched by the photoinduced protonation of the carbonyl group at the β position (O9). After protonation, a series of fast reaction steps occurred to eventually generate the triplet state α-lapachone intermediate. This triplet state of α-lapachone then underwent intersystem crossing to produce the ground singlet state of α-lapachone as the final product. 1,2-Naphthoquinone is examined in acetonitrile and water solutions in order to elucidate the important roles that water and the pyran ring play during the photoconversion from β-lapachone to α-lapachone. β-Lapachone can also be converted to α-lapachone in the ground state when a strong acid is added to an aqueous solution. Our investigation indicates that β-lapachone can be converted to α-lapachone by photoconversion in aqueous solutions by a protonation-assisted singlet excited state reaction or by an acid-assisted ground state reaction.

Topics: Acetonitriles; Naphthoquinones; Photochemical Processes; Protons; Quantum Theory; Solutions; Spectrum Analysis

The treatment of activated B cell-like DLBCL (ABC-DLBCL) is one of the urgent unmet medical needs because it is the most resistant DLBCL subtype to current therapies eagerly awaiting effective therapeutic strategies. Recently, the paracaspase MALT1 has emerged as a promising therapeutic target for the treatment of ABC-DLBCL. Herein, we report a new class of MALT1 inhibitors developed by high-throughput screening and structure-based drug design. The original hit, 4-amino-1,2-naphthoquinone series inhibited MALT1 activity but suffered from poor cellular activity. The extensive pharmacophore search led to the discovery of structurally similar β-lapachone that is a direct inhibitor of MALT1 and possesses favorable physicochemical properties. Molecular simulation studies suggested the possibility of the formation of a covalent bond between MALT1 and β-lapachone, which was corroborated by experimental wash-out studies. Inspired by this, we explored the structure-activity relationships by incorporating electron-withdrawing substituents at C8 position of β-lapachone. These MALT1 inhibitors exhibited potent antiproliferative activity to OCI-LY3 cell line and inhibited the cleavage of CYLD mediated MALT1.

Topics: Antineoplastic Agents; Caspases; Cell Line, Tumor; Cell Proliferation; Humans; Lymphoma, Large B-Cell, Diffuse; Models, Molecular; Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; Naphthoquinones; Neoplasm Proteins; Structure-Activity Relationship

Oxidative stress is a commonly cited mechanism of toxicity of environmental agents. Ubiquitous environmental chemicals such as the diesel exhaust component 1,2-naphthoquinone (1,2-NQ) induce oxidative stress by redox cycling, which generates hydrogen peroxide (H2O2). Cysteinyl thiolate residues on regulatory proteins are subjected to oxidative modification by H2O2 in physiological contexts and are also toxicological targets of oxidant stress induced by environmental contaminants. We investigated whether exposure to environmentally relevant concentrations of 1,2-NQ can induce H2O2-dependent oxidation of cysteinyl thiols in regulatory proteins as a readout of oxidant stress in human airway epithelial cells. BEAS-2B cells were exposed to 0-1000 μM 1,2-NQ for 0-30 min, and levels of H2O2 were measured by ratiometric spectrofluorometry of HyPer. H2O2-dependent protein sulfenylation was measured using immunohistochemistry, immunoblotting, and isotopic mass spectrometry. Catalase overexpression was used to investigate the relationship between H2O2 generation and protein sulfenylation in cells exposed to 1,2-NQ. Multiple experimental approaches showed that exposure to 1,2-NQ at concentrations as low as 3 μM induces H2O2-dependent protein sulfenylation in BEAS-2B cells. Moreover, the time of onset and duration of 1,2-NQ-induced sulfenylation of the regulatory proteins GAPDH and PTP1B showed significant differences. Oxidative modification of regulatory cysteinyl thiols in human lung cells exposed to relevant concentrations of an ambient air contaminant represents a novel marker of oxidative environmental stress.

Topics: Cells, Cultured; Humans; Models, Biological; Naphthoquinones; Oxidative Stress; Protein Processing, Post-Translational; Proteins; Sulfenic Acids

Biflorin is an o-naphthoquinone isolated from the roots of the plant Capraria biflora L. (Scrophulariaceae). In this study, the cytotoxic effects of biflorin were verified, and late apoptosis was detected in various cancer cell lines by in situ analysis. The cytotoxicity was further evaluated exclusively for 48 h of treatment in different tumor and non-tumor cell lines (Hep-2, HeLa, HT-29, A-375, and A-549, and HEK-293, respectively). The results indicated that biflorin induced selective cytotoxicity in tumor cells. HeLa cells were more susceptible to biflorin, followed by HT-29, A-549, A-375, and Hep-2 at all concentrations (range 5-50 μg/mL), and the highest half-maximal inhibitory concentration IC50 (56.01 ± 1.17 μg/mL) was observed in HEK-293 cells. Late apoptotic/necrotic events, observed by in situ immunostaining with Annexin V, varied with each cell line; an increase in late apoptotic events was observed corresponding to the increase in biflorin dosage. Hep-2 cells showed a greater percentage of late apoptotic events among the tumor cell lines when treated with higher concentrations of biflorin (69.63 ± 2.28%). The non-tumor HEK-293 line showed greater resistance to late apoptotic events, as well as a lower level of cytotoxicity (77.69 ± 6.68%) than the tested tumor lines. The data presented indicate that biflorin showed an important, possibly selective, cytotoxicity against tumor cell lines, thereby revealing a promising novel substance with potential anticancer activity for tumor therapy.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Cell Line, Tumor; HEK293 Cells; Humans; Naphthoquinones; Neoplasms; Scrophulariaceae

There is increasing interest in using live cell imaging to monitor not just individual intracellular endpoints, but to investigate the interplay between multiple molecular events as they unfold in real time within the cell. A major impediment to simultaneous acquisition of fluorescent signals from multiple probes is that emission spectra of many fluorophores overlap, often with maxima that are only a few nanometers apart. Spectral acquisition of mixed fluorescence signals captured within a dedicated scanning range can be used to quantitatively separate signals into component spectra. We report here the development of a novel live cell application of spectral unmixing for the simultaneous monitoring of intracellular events reported by closely-emitting fluorophores responding dynamically to external stimuli. We validate the performance of dynamic spectral unmixing microscopy (DynSUM) using genetically encoded sensors to simultaneously monitor changes in glutathione redox potential (Egsh) and H2O2 production in living cells exposed to oxidizing and reducing agents. We further demonstrate the utility of the DynSUM approach to observe the relationship between the increases in Egsh and H2O2 generation induced in airway epithelial cells exposed to an environmental electrophile.

Topics: Antioxidants; Cell Line; Green Fluorescent Proteins; Humans; Hydrogen Peroxide; Microscopy, Fluorescence; Naphthoquinones; Oxidation-Reduction; Oxidative Stress; Single-Cell Analysis

We describe a novel method for the measurement of protein tyrosine phosphatase (PTP) activity in single human airway epithelial cells (hAECs) using capillary electrophoresis. This technique involved the microinjection of a fluorescent phosphopeptide that is hydrolyzed specifically by PTPs. Analyses in BEAS-2B immortalized bronchial epithelial cells showed rapid PTP-mediated dephosphorylation of the substrate (2.2 pmol min(-1) mg(-1)) that was blocked by pretreatment of the cells with the PTP inhibitors pervanadate, Zn(2+), and 1,2-naphthoquinone (76%, 69%, and 100% inhibition relative to PTP activity in untreated controls, respectively). These studies were then extended to a more physiologically relevant model system: primary hAECs cultured from bronchial brushings of living human subjects. In primary hAECs, dephosphorylation of the substrate occurred at a rate of 2.2 pmol min(-1) mg(-1) and was also effectively inhibited by preincubation of the cells with the inhibitors pervanadate, Zn(2+), and 1,2-naphthoquinone (91%, 88%, and 87% median PTP inhibition, respectively). Reporter proteolysis in single BEAS-2B cells occurred at a median rate of 43 fmol min(-1) mg(-1) resulting in a mean half-life of 20 min. The reporter displayed a similar median half-life of 28 min in these single primary cells. Finally, single viable epithelial cells (which were assayed for PTP activity immediately after collection by bronchial brushing of a human volunteer) showed dephosphorylation rates ranging from 0.34 to 36 pmol min(-1) mg(-1) (n = 6). These results demonstrate the utility and applicability of this technique for the ex vivo quantification of PTP activity in small, heterogeneous, human cells and tissues.

Topics: Bronchi; Cell Line; Electrophoresis, Capillary; Enzyme Inhibitors; Epithelial Cells; Half-Life; Humans; Hydrolysis; Microinjections; Naphthoquinones; Phosphoproteins; Primary Cell Culture; Protein Tyrosine Phosphatases; Single-Cell Analysis; Vanadates

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

High diesel exhaust particle levels are associated with increased health effects; however, knowledge on the impact of its chemical contaminant 1,2-naphthoquinone (1,2-NQ) is limited. We investigated whether postnatal and adult exposures to 1,2-NQ influence allergic reaction and the roles of innate and adaptive immunity. Male neonate (6 days) and adult (56 days) C57Bl/6 mice were exposed to 1,2-NQ (100 nM; 15 min) for 3 days, and on day 59, they were sensitized and later challenged with ovalbumin (OVA). Airway hyper-responsiveness (AHR) and production of cytokines, immunoglobulin E (IgE) and leukotriene B4 (LTB4) were measured in the airways. Postnatal exposure to 1,2-NQ activated dendritic cells in splenocytes by increasing expressing cell surface molecules (e.g., CD11c). Co-exposure to OVA effectively polarized T helper (Th) type 2 (Th2) by secreting Th2-mediated cytokines. Re-stimulation with unspecific stimuli (PMA and ionomycin) generated a mixed Th1 (CD4(+)/IFN-γ(+)) and Th17 (CD4(+)/IL-17(+)) phenotype in comparison with the vehicle-matched group. Postnatal exposure to 1,2-NQ did not induce eosinophilia in the airways at adulthood, although it evoked neutrophilia and exacerbated OVA-induced eosinophilia, Th2 cytokines, IgE and LTB4 production without affecting AHR and mast cell degranulation. At adulthood, 1,2-NQ exposure evoked neutrophilia and increased Th1/Th2 cytokine levels, but failed to affect OVA-induced eosinophilia. In conclusion, postnatal exposure to 1,2-NQ increases the susceptibility to antigen-induced asthma. The mechanism appears to be dependent on increased expression of co-stimulatory molecules, which leads to cell presentation amplification, Th2 polarization and enhanced LTB4, humoral response and Th1/Th2 cytokines. These findings may be useful for future investigations on treatments focused on pulmonary illnesses observed in children living in heavy polluted areas.

Topics: Adaptive Immunity; Aging; Air Pollutants; Animals; Animals, Newborn; Cytokines; Disease Susceptibility; Immunity, Innate; Immunoglobulin E; Inhalation Exposure; Leukotriene B4; Male; Naphthoquinones; Ovalbumin; Pneumonia; Respiratory Hypersensitivity; Vehicle Emissions

Covalent modification of cellular proteins by electrophiles affects electrophilic signal transduction and the dysfunction of enzymes that is involved in cytotoxicity. We have recently found a unique reaction which restores glyceraldehyde-3-phosphate dehydrogenase (GAPDH) that has been modified by 1,2-naphthoquinone (1,2-NQ) through a glutathione (GSH)-dependent S-transarylation reaction. We report here that ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) undergoes the same reaction. Exposure of human neuroblastoma SH-SY5Y cells to 1,2-NQ after pretreatment with buthionine sulfoximine (BSO) to deplete GSH resulted in an enhancement of covalent modification of UCH-L1 by 1,2-NQ. With recombinant human UCH-L1, we demonstrated that UCH-L1 underwent arylation by 1,2-NQ through Cys152 and Lys4, thereby decreasing its catalytic activity. Addition of GSH to an incubation mixture of 1,2-NQ-UCH-L1 adduct partially restored this decline in enzyme activity which was accompanied by decreased covalent attachment of 1,2-NQ, together with production of 1,2-NQ-GSH adduct. UCH-L1 in which Lys4 was mutated exhibited a lower level of covalent modification and enzyme inhibition, but completely recovered after addition of GSH. Taken together, these results suggest that Cys152 modification in UCH-L1 by 1,2-NQ is reversible via GSH-mediated S-transarylation reaction whereas Lys4 modification by 1,2-NQ is irreversible by GSH. Because UCH-L1 dysfunction has been associated with neurodegeneration, the electrophilic modification of Lys rather than Cys in UCH-L1 may be implicated in such neurodegenerative diseases.

Topics: Blotting, Western; Cell Line, Tumor; Cysteine; Electrophoresis, Gel, Two-Dimensional; Glutathione; Humans; Lysine; Naphthoquinones; Recombinant Proteins; Ubiquitin Thiolesterase; Ubiquitination

Using human lung epithelial A549 cells, viability was measured by MTT assay after treated with 1-nitropyrene (1-NP); lactate dehydrogenase (LDH) leakage was determined to evaluate the cellular membrane injury; DNA damage was detected with comet assay; reactive oxygen species (ROS) generation was measured with fluorescent probe. The combined toxic effects of 1-NP and 1,2-naphthoquinone (1,2-NQ) on A549 were also evaluated. 1-NP caused a significantly concentration-dependent and time-dependent viability decrease. The LC50 for 24 h and 48 h were 5.2 μmol x L(-1) and 2.8 μmol x L(-1), respectively. DNA damage and intracellular ROS levels were also increased significantly through a dose-dependent manner after exposure to 1-NP. The LDH leakage were not significantly changed. Compared with the groups treated with 1-NP alone, the viability and LDH leakage was not changed significantly in combined-treated groups with 1-NP and 1,2-NQ. However, the DNA damage and ROS levels were significantly reduced in the combined-treated groups compared with the groups treated with 1-NP alone. These results suggest that 1-NP may mediated the genotoxic and cytotoxic effects through ROS generation, and pretreatment with 1,2-NQ, may inhibit the ROS generation induced by 1-NP, and thereby reducing the DNA damage in A549 cells.

Topics: Cell Line, Tumor; Comet Assay; DNA Damage; Epithelial Cells; Humans; L-Lactate Dehydrogenase; Lung; Naphthoquinones; Pyrenes; Reactive Oxygen Species

1,2-Naphthoquinone (1,2-NQ) is found to be an electrophile contaminated in the atmosphere. Although we found that 1,2-NQ activates epidermal growth factor receptor (EGFR) coupled to inhibition of protein tyrosine phosphatase 1B (PTP1B) activity through covalent modification of Cys121 in human epithelial A431 cells, modulation of its downstream signal transduction pathway caused by 1,2-NQ remains to be elucidated. In the present study, we examined whether 1,2-NQ could affect such cellular signaling in human pulmonary A549 cells. Exposure of A549 cells to 1,2-NQ increased EGFR phosphorylation, resulting in activation of MEK/ERK signaling that was blocked by either PD15035 or PD98059. As a result, DNA binding activity of transcription factor AP-1 was enhanced during exposure to 1,2-NQ in the cells. These results suggest that the atmospheric electrophile phosphorylates EGFR, thereby activating the MEK/ERK/AP-1 signal transduction pathway in A549 cells.

Topics: Air Pollutants; Cells, Cultured; DNA; ErbB Receptors; Humans; MAP Kinase Signaling System; Naphthoquinones; Phosphorylation; Protein Binding; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Signal Transduction; Transcription Factor AP-1

Naphthalene induces cataract formation through the accumulation of its reactive metabolite, 1,2-naphthoquinone (1,2-NQ), in the ocular lens. 1,2-NQ increases lens protein oxidation and disrupts fiber cell membrane function; however, the association of these effects with changes in membrane structure is not understood. The goal of this study was to determine the direct effects of 1,2-NQ on membrane lipid oxidation and structural organization.. Iodometric approaches were used to measure the effects of naphthalene and 1,2-NQ on lipid hydroperoxide (LOOH) formation in model membranes composed of cholesterol and dilinoleoylphosphatidylcholine. Membrane samples were prepared at various cholesterol-to-phospholipid mole ratios and subjected to autoxidation at 37°C for 48 hours in the absence or presence of either agent alone (0.1-5.0 μM) or in combination with vitamin E. Small-angle x-ray diffraction was used to measure the effects of naphthalene and 1,2-NQ on membrane structure before and after exposure to oxidative stress.. 1,2-NQ increased LOOH formation by 250% (P < 0.001) and 350% (P < 0.001) at 1.0 and 5.0 μM, respectively, whereas naphthalene decreased LOOH levels by 25% (P < 0.01) and 10% (NS). The pro-oxidant effect of 1,2-NQ was inversely affected by membrane cholesterol enrichment and completely blocked by vitamin E. 1,2-NQ also increased cholesterol domain formation by 360% in membranes exposed to oxidative stress; however, no significant changes in membrane lipid organization were observed with naphthalene under the same conditions.. These data suggest a novel mechanism for naphthalene-induced cataract, facilitated by the direct effects of 1,2-NQ on lipid peroxidation and cholesterol domain formation.

Topics: Analysis of Variance; Cataract; Cholesterol; Humans; Lipid Peroxidation; Lipid Peroxides; Membrane Lipids; Models, Biological; Naphthalenes; Naphthoquinones

Topics: Catalysis; Chlorides; Cycloaddition Reaction; Ferric Compounds; Naphthalenes; Naphthoquinones; Silanes; Stereoisomerism

Toxicological studies have correlated inflammatory effects of diesel exhaust particles (DEP) with its organic constituents, such as the organic electrophile 1,2-naphthoquinone (1,2-NQ).. To elucidate the mechanisms involved in 1,2-NQ-induced inflammatory responses, we examined the role of oxidant stress in 1,2-NQ-induced expression of inflammatory and adaptive genes in a human airway epithelial cell line.. We measured cytosolic redox status and hydrogen peroxide (H2O2) in living cells using the genetically encoded green fluorescent protein (GFP)-based fluorescent indicators roGFP2 and HyPer, respectively. Expression of interleukin-8 (IL-8), cyclooxygenase-2 (COX-2), and heme oxygenase-1 (HO-1) mRNA was measured in BEAS-2B cells exposed to 1,2-NQ for 1-4 hr. Catalase overexpression and metabolic inhibitors were used to determine the role of redox changes and H2O2 in 1,2-NQ-induced gene expression.. Cells expressing roGFP2 and HyPer showed a rapid loss of redox potential and an increase in H2O2 of mitochondrial origin following exposure to 1,2-NQ. Overexpression of catalase diminished the H2O2-dependent signal but not the 1,2-NQ-induced loss of reducing potential. Catalase overexpression and inhibitors of mitochondrial respiration diminished elevations in IL-8 and COX-2 induced by exposure to 1,2-NQ, but potentiated HO-1 mRNA levels in BEAS cells.. These data show that 1,2-NQ exposure induces mitochondrial production of H2O2 that mediates the expression of inflammatory genes, but not the concurrent loss of reducing redox potential in BEAS cells. 1,2-NQ exposure also causes marked expression of HO-1 that appears to be enhanced by suppression of H2O2. These findings shed light into the oxidant-dependent events that underlie cellular responses to environmental electrophiles.

Topics: Air Pollutants; Bronchi; Catalase; Cell Line; Cyclooxygenase 2; Environmental Health; Epithelial Cells; Gene Expression Regulation; Green Fluorescent Proteins; Heme Oxygenase-1; Humans; Hydrogen Peroxide; Inflammation; Interleukin-8; Naphthoquinones; Oxidation-Reduction; Oxidative Stress; Particulate Matter; Reactive Oxygen Species; RNA, Messenger; Vehicle Emissions

In the present study substituted 1,2-naphthoquinones were synthesized, purified and characterized by spectroscopic studies (UV, FT-IR, ¹H NMR, ¹³ C NMR and elemental analysis). These compounds were evaluated for cytotoxicity against a panel of human cancer cell lines (Hep-G₂ for liver sarcoma, MG-63 for osteosarcoma and MCF-7 for human breast cancer). The cells were dosed with these ortho-naphthoquinone derivatives at varying concentrations, and cell viability was measured by a 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay with doxorubicin as positive control. Significant anticancer activities were observed in vitro for some members of the series, and compounds 1,2-naphthoquinone 2-thiosemicarbazone, 1,2-naphthoquinone-2-semicarbazone, 4-amino-1,2-naphthoquinone 2-thiosemicarbazone and 4-amino-1,2-naphthoquinone-2-semicarbazone are active cytotoxic agents against different cancer cell lines with IC₅₀ values in the range of 5.73-17.67 μM. The obtained data suggested that better anticancer activity was linked with introduction of thiosemicarbazone and semicarbazone moiety in 1,2-naphthoquinone ring system. Outcomes of experimentation also reveal that incorporation of amino group in 1,2-naphthoquinone moiety contributes positively for cytotoxic action of compounds. Docking experiments showed a good correlation between their calculated interaction energies with the topoisomerase-II and the observed IC₅₀ values of all these compounds.

Topics: Absorption; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chemistry Techniques, Synthetic; DNA Topoisomerases, Type II; Humans; Inhibitory Concentration 50; Models, Molecular; Naphthoquinones

1,2-Naphthoquinone (1,2-NQ) is an atmospheric chemical capable of (1) redox cycling with electron donors and (2) covalent modification of nucleophilic groups on proteins. In the present study, we investigated its interaction with the redox protein, thioredoxin1 (Trx1), which led to oxidative stress-dependent cell damage. In experiments with purified wild-type Trx1 and its double mutant (32S/35S Trx1), we found that incubation of Trx1 with 1,2-NQ resulted in a redox cycling reaction, generating superoxide and hydrogen peroxide involving Cys32 and Cys35 and an arylation reaction resulting in covalent modification of Lys85 together with a loss of Trx activity. A significant fraction of the lost Trx1 activity following interaction with 1,2-NQ was restored by dithiothreitol. Exposure of RAW264.7 cells to 1,2-NQ generated reactive oxygen species (ROS) and caused a decrease in Trx activity. Trx is a negative regulator of apoptosis signal-regulating kinase 1 (ASK1), and under the conditions of the experiment, 1,2-NQ activated ASK1 and p38, leading to PARP cleavage and apoptotic cell death that were blocked by pretreatment with polyethylene glycol-catalase. These results suggest that Trx1 readily undergoes oxidative modification by 1,2-NQ through the proximal thiols Cys32 and Cys35. It seems likely that ROS production concomitant with decline in cellular Trx activity plays a role in the activation of ASK1/p38 signaling to promote apoptotic cell death cause by 1,2-NQ exposure.

Topics: Animals; Biocatalysis; Cell Death; Cell Survival; Cells, Cultured; Cysteine; MAP Kinase Kinase Kinase 5; Mice; Naphthoquinones; Oxidation-Reduction; p38 Mitogen-Activated Protein Kinases; Reactive Oxygen Species; Signal Transduction; Thioredoxins

New, simple and rapid spectrophotometric method has been developed and validated for the assay of two macrolide drugs, azithromycin (AZT) and erythromycin (ERY) in pure and pharmaceutical formulations. The proposed method was based on the reaction of AZT and ERY with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium at 25 °C to form an orange-colored product of maximum absorption peak at 452 nm. All variables were studied to optimize the reaction conditions and the reaction mechanism was postulated. Beer's law was obeyed in the concentration range 1.5-33.0 and 0.92-8.0 μg mL(-1) with limit of detection values of 0.026 and 0.063 μg mL(-1) for AZT and ERY, respectively. The calculated molar absorptivity values are 4.3 × 10(4) and 12.3 × 10(4) L mol(-1) cm(-1) for AZT and ERY, respectively. The proposed methods were successfully applied to the determination of AZT and ERY in formulations and the results tallied well with the label claim. The results were statistically compared with those of an official method by applying the Student's t-test and F-test. No interference was observed from the concomitant substances normally added to preparations.

Topics: Anti-Bacterial Agents; Azithromycin; Coloring Agents; Erythromycin; Limit of Detection; Naphthoquinones; Pharmaceutical Preparations; Spectrophotometry; Sulfonic Acids

Quinones are reactive chemical species that cause cellular damage by modifying protein thiols and/or catalyzing the reduction of oxygen to reactive oxygen species, thereby promoting oxidative stress. Transcription factor Nrf2 plays a crucial role in cellular defense against electrophilic modification and oxidative stress. In studies using 1,2-naphthoquinone (1,2-NQ) as a model quinone, we found that Keap1, the negative regulator of Nrf2, was readily arylated at its reactive thiols by 1,2-NQ. Exposure of primary mouse hepatocytes to 1,2-NQ resulted in the activation of Nrf2 and the upregulation of some of Nrf2's downstream genes. This interaction was further investigated in hepatocytes from Nrf2 knockout mice in which the proteins responsible for the metabolism and excretion of 1,2-NQ are minimally expressed. The chemical modification of cellular proteins by 1,2-NQ was enhanced by Nrf2 deletion, resulting in increased toxicity. However, deletion of the negative regulatory protein, Keap1, drastically reduced the covalent binding by 1,2-NQ and its cellular toxicity. Experiments with chemicals that inhibit the biotransformation and extracellular excretion of 1,2-NQ suggest that 1,2-NQ undergoes detoxification and excretion into the extracellular space predominantly by two-electron reduction and subsequent glucuronidation by NAD(P)H:quinone oxidoreductase 1 and uridine 5'-diphosphate-glucuronosyltransferases, followed by multidrug resistance-associated protein-dependent excretion. These findings suggest that the Keap1/Nrf2 system is essential for the prevention of cell damage resulting from exposure to 1,2-NQ.

Topics: Adaptor Proteins, Signal Transducing; Animals; Cells, Cultured; Cytoskeletal Proteins; Glucuronosyltransferase; Hepatocytes; Kelch-Like ECH-Associated Protein 1; Mice; Mice, Knockout; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; NF-E2-Related Factor 2; Peptides; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

1,2-Naphthoquinone (1,2-NQ) is an atmospheric electrophile that reacts covalently with protein thiols. Our previous study revealed that exposure of bovine aortic endothelial cells to 1,2-NQ causes covalent modification of cAMP response element-binding protein (CREB), thereby inhibiting its DNA binding activity and substantial gene expression of B-cell lymphoma-2 (Bcl-2) that is regulated by this transcription factor. In this study, we identified the modification sites of CREB that are associated with the decreased transcriptional activity. Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis indicated that three amino acids (Cys-286, Lys-290, and Lys-319) were irreversibly modified by 1,2-NQ. Mutational analysis revealed that electrophilic modification of Cys-286, but not the other two amino acids, at the DNA binding domain is essential for the reduced CREB activity. Substitution of Cys-286 with tryptophan (C286W), which mimics CREB modification by 1,2-NQ, supported this notion. These results suggest that the covalent interaction of CREB with 1,2-NQ through Cys-286 blocks the DNA binding activity of CREB, resulting in the repression of CREB-regulated genes.

Topics: Cell Line, Tumor; Cyclic AMP Response Element-Binding Protein; Cysteine; Environmental Pollutants; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Mutagens; Naphthoquinones

A novel comb-like derivative CPEG-g-DNQ was prepared by incorporating light responsive 2-diazo-1,2-naphthoquinone (DNQ) groups into the structure of comb-like poly(ethylene glycol) (CPEG). DLS and TEM results showed that CPEG-g-DNQ self-assembled into spherical micelles with an average size of about 135 nm in water. Upon exposure to light, the micelles could be disrupted because of the conversion of hydrophobic DNQ to hydrophilic 3-indenecarboylic acid. Additionally, hydrophobic coumarin 102 was successfully loaded into the micelles and photo-induced ON-OFF release was demonstrated by fluorescence spectroscopy. MTT assay revealed that the micelles are biocompatible. These photo-responsive micelles might have great potential for controlled release of hydrophobic drugs.

Topics: Biocompatible Materials; Drug Carriers; Drug Delivery Systems; Hep G2 Cells; Humans; Hydrophobic and Hydrophilic Interactions; Micelles; Naphthoquinones; Photochemical Processes; Polyethylene Glycols; Polymers; Ultraviolet Rays

Many cellular proteins with reactive thiols form covalent bonds with electrophiles, thereby modifying their structures and activities. Here, we describe the recovery of a glycolytic protein, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), from such an electrophilic attack by 1,2-napthoquinone (1,2-NQ). GAPDH readily formed a covalent bond with 1,2-NQ through Cys152 at a low concentration (0.2 μM) in a cell-free system, but when human epithelial A549 cells were exposed to this quinone at 20 μM, only minimal binding was observed although extensive binding to numerous other cellular proteins occurred. Depletion of cellular glutathione (GSH) with buthionine sulfoximine (BSO) resulted in some covalent modification of cellular GAPDH by 1,2-NQ and a significant reduction of GAPDH activity in the cells. Incubation of native, but not boiled, human GAPDH that had been modified by 1,2-NQ with GSH resulted in a concentration-dependent removal of 1,2-NQ from the GAPDH conjugate, accompanied by partial recovery of lost catalytic activity and formation of a 1,2-NQ-GSH adduct (1,2-NQ-SG). While GAPDH is recognized as a multifunctional protein, our results show that GAPDH also has a unique ability to recover from electrophilic modification by 1,2-NQ through a GSH-dependent S-transarylation reaction.

Topics: Buthionine Sulfoximine; Cell Line; Cell-Free System; Cloning, Molecular; Epithelial Cells; Escherichia coli; Glutathione; Glyceraldehyde-3-Phosphate Dehydrogenases; Glycolysis; Humans; Mutation; Naphthoquinones; Oxidation-Reduction; Plasmids; Protein Denaturation; Protein Processing, Post-Translational; Recombinant Proteins; Sulfhydryl Compounds; Transformation, Bacterial

1,2-Naphthoquinone (1,2-NQ) is electrophilic, and forms covalent bonds with protein thiols, but its two-electron reduction product 1,2-dihydroxynaphthalene (1,2-NQH(2)) is not, so enzymes catalyzing the reduction with reduced pyridine nucleotides as cofactors could protect cells from electrophile-based chemical insults. To assess this possibility, we examined proteins isolated from the 9000g supernatant from mouse liver for 1,2-NQ reductase activity using an HPLC assay procedure for the hydroquinone of 1,2-NQ and Cibacron Blue 3GA column chromatography and Western blot analysis with specific antibody to determine 1,2-NQ-bound proteins. Among the proteins with high affinities for pyridine nucleotides that also inhibited 1,2-NQ-protein adduct formation in the presence of NADH, a 37-kDa protein was found and identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Using recombinant human GAPDH, we found that this glycolytic enzyme indeed catalyzes the two-electron reduction of 1,2-NQ accompanied by extensive NADH consumption under 20% oxygen conditions. When either 1,2-NQH(2) or 1,2-NQ was incubated with GAPDH in the presence of NADH, minimal covalent bonding to the enzyme occurred compared to that in its absence. These results indicate that GAPDH can inhibit 1,2-NQ-based electrophilic protein modification by conversion to the nonelectrophilic 1,2-NQH(2) via an NADH-dependent process.

Topics: Amino Acid Sequence; Animals; Biocatalysis; Glyceraldehyde-3-Phosphate Dehydrogenases; Humans; Male; Mice; Mice, Inbred ICR; Molecular Sequence Data; NAD; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones

1,2-Naphthoquinone (1,2-NQ) is an electrophile found in the atmosphere, which reacts readily with protein nucleophiles to form a stable protein adduct. Peroxiredoxin 6 (Prdx6) is predominantly expressed in lung tissue and functions in antioxidant defense by facilitating the repair of damaged cell membranes via reduction of peroxidized phospholipids. In the present study, human A549 pulmonary epithelial cells were exposed to 1,2-NQ to explore whether 1,2-NQ can bind covalently to Prdx6, thereby disrupting its catalytic activity. Two-dimensional SDS/PAGE followed by western blot analysis with a specific antibody against 1,2-NQ showed that Prdx6 was covalently modified by 1,2-NQ. Using purified human Prdx6, it was found that 1,2-NQ bound covalently to Prdx6 through Cys47, Lys144 and Cys91, resulting in a significant reduction in phospholipase A(2) activity. These results suggest that arylation of Prdx6 by 1,2-NQ may, at least in part, be involved in the cellular toxicity induced by 1,2-NQ.

Topics: Air Pollutants; Blotting, Western; Cell Line; Chromatography, Liquid; Electrophoresis, Polyacrylamide Gel; Epithelial Cells; Humans; Mass Spectrometry; Naphthoquinones; Peroxiredoxin VI; Phospholipases A2; Protein Binding

The environmental chemical 1,2-naphthoquinone (1,2-NQ) is implicated in the exacerbation of airways diseases induced by exposure to diesel exhaust particles (DEP), which involves a neurogenic-mediated mechanism. Plasma extravasation in trachea, main bronchus and lung was measured as the local (125)I-bovine albumin accumulation. RT-PCR quantification of TRPV1 and tachykinin (NK(1) and NK(2)) receptor gene expression were investigated in main bronchus. Intratracheal injection of DEP (1 and 5 mg/kg) or 1,2-NQ (35 and 100 nmol/kg) caused oedema in trachea and bronchus. 1,2-NQ markedly increased the DEP-induced responses in the rat airways in an additive rather than synergistic manner. This effect that was significantly reduced by L-732,138, an NK(1) receptor antagonist, and in a lesser extent by SR48968, an NK(2) antagonist. Neonatal capsaicin treatment also markedly reduced DEP and 1,2-NQ-induced oedema. Exposure to pollutants increased the TRPV1, NK(1) and NK(2) receptors gene expression in bronchus, an effect was partially suppressed by capsaicin treatment. In conclusion, our results are consistent with the hypothesis that DEP-induced airways oedema is highly influenced by increased ambient levels of 1,2-NQ and takes place by neurogenic mechanisms involving up-regulation of TRPV1 and tachykinin receptors.

Topics: Air Pollutants; Animals; Female; Inflammation; Male; Naphthoquinones; Neurons, Afferent; Rats; Rats, Wistar; Respiratory System; TRPV Cation Channels; Vehicle Emissions

The synthesis and characterization of three novel iridium(III) complexes and one rhodium(III) complex with 1-nitroso-2-naphthol (3) chelating as a 1,2-naphthoquinone-1-oximato ligand are described. The reaction of mu(2)-halogenido-bridged dimers [(eta(5)-C(5)Me(5))IrX(2)](2) [X is Cl (1a), Br (1b), I (1c)] and [(eta(5)-C(5)Me(5))RhCl(2)](2) (2a) with 3 in CH(2)Cl(2) yields the mononuclear complexes (eta(5)-C(5)Me(5))IrX(eta(2)-C(10)H(6)N(2)O) (4a, 4b, 4c) and (eta(5)-C(5)Me(5))RhCl(eta(2)-C(10)H(6)N(2)O) (5a). All compounds were characterized by their (1)H and (13)C NMR, IR, and mass spectra, UV/vis spectra were recorded for 4a and 5a. The X-ray structure analyses revealed a pseudo-octahedral "piano-stool" configuration for the metals with bidentate coordination through oximato-N and naphthoquinone-O, forming a nearly planar five-membered metallacycle. The metal complexes 4a and 5a were evaluated in respect to their cytotoxicity and binding affinity toward double-stranded DNA. As determined in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, both exerted a much stronger cytotoxic effect toward HeLa and HL60 cancer cell lines than did cisplatin. The remarkable cytotoxicity of the compounds tested may be attributed to necrosis, rather than to apoptosis, as it is evidenced by the caspase-3/7 activation assay. No clear evidence was found for interaction with double-stranded DNA. The melting experiments showed no significant differences between thermodynamic parameters of intact DNA and DNA incubated with 3, 4a, or 5a, although these derivatives altered DNA recognition by the BamHI restriction enzyme. Therefore, the screened iridium and rhodium complexes 4a and 5a may still be interesting as potential anticancer drugs owing to their high cytotoxicity toward cancer cell lines, whereas they do not modify DNA in a way similar to that of cisplatin.

Topics: Antineoplastic Agents; Caspase 3; Caspase 7; Cell Death; Cell Line, Tumor; Cells, Cultured; Circular Dichroism; Coordination Complexes; Crystallography, X-Ray; DNA; HeLa Cells; Humans; Iridium; Models, Molecular; Naphthoquinones; Neoplasms; Rhodium

To explore biodegradation of 2-naphthol and its metabolites accumulated in wastewater treatment, a series of bio-degradation experiments were conducted. Two main metabolites of 2-naphthol, 1,2-naphthalene-diol and 1,2-naphthoquinone, were identified by high-performance liquid chromatography with standards. Combining fungus Aspergillus niger with bacterium Bacillus subtilis in the treatment enhanced 2-naphthol degradation efficiency, lowered the accumulation of the two toxic metabolites. There were two main phases during the degradation process by the kinetic analysis: 2-naphthol was first partly degraded by the fungus, producing labile and easily accumulated metabolites, and then the metabolites were mainly degraded by the bacterium, attested by the degradation processes of 1,2-naphthalene-diol and 1,2-naphthoquinone as sole source of carbon and energy. Sodium succinate, as a co-metabolic substrate, was the most suitable compound for the continuous degradation. The optimum concentration of 2-naphthol was 50 mg/L. The overall 2-naphthol degradation rate was 92%, and the CODcr removal rate was 80% on day 10. These results indicated that high degradation rate of 2-naphthol should not be considered as the sole desirable criterion for the bioremediation of 2-naphthol-contaminated soils/wastewater.

Topics: Aspergillus niger; Bacillus subtilis; Biodegradation, Environmental; Kinetics; Minerals; Naphthols; Naphthoquinones

Naphthalene undergoes biotransformation by a variety of enzymes to yield 1,2-naphthoquinone (1,2-NQ), a reactive metabolite that binds covalently to proteins. Because this covalent modification is thought to account for naphthalene toxicity, a procedure to detect 1,2-NQ bound to macromolecules is required. In this study, we prepared a polyclonal antibody against 1,2-NQ and examined the specificities of the antibody for various aromatic structures and for the regiochemistry of the quinone functionality. Western blot analysis revealed that the antibody prepared against 1,2-NQ recognized the naphthalene moiety with the ortho-dicarbonyl group, but not with the para-dicarbonyl group; in addition, little cross-reactivity of ortho-quinones with different numbers of aromatic rings (n = 1, 3, 4, 5, 6) was seen. Dot blot and Western blot analyses with the polyclonal antibody enabled quantitative determination of the formation of protein-bound 1,2-NQ during the metabolic activation of naphthalene. The present method can be expected to applicable for the identification of the molecular targets of 1,2-NQ derived from naphthalene in cells and tissues.

Topics: Adjuvants, Immunologic; Animals; Antibodies; Biotransformation; Blotting, Western; Cells, Cultured; Electrophoresis, Polyacrylamide Gel; Environmental Pollutants; Hemocyanins; Hepatocytes; Immune Sera; Immunochemistry; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Naphthalenes; Naphthoquinones; Protein Binding; Proteins; Rabbits

1,2-Naphthoquinone (1,2-NQ) is an uncoupling agent for constitutive nitric oxide (NO) synthase (NOS), thereby inhibiting its catalytic activity. However, little information on whether this quinone can affect inducible NOS (iNOS) is available. To address this issue, we examined the effect of 1,2-NQ on lipopolysaccharide (LPS)-mediated induction of iNOS. Exposure of LPS-challenged RAW264.7 cells to 1,2-NQ resulted in decreased NO formation through a reduction in iNOS production. Under these conditions, LPS-induced activation of nuclear transcription factor-κB (NF-κB) coupled to phosphorylation of inhibitory κBα (IκBα) declined. Similar effects of 1,2-NQ were observed in the lungs of mice exposed to LPS. Using IκB kinase β (IKKβ)-transfected RAW264.7 cells and recombinant IKKβ protein, we found that 1,2-NQ diminished the phosphorylation of IκB by IKKβ enzymatic activity. Taken together, these results suggest that 1,2-NQ reduces iNOS-catalyzed NO production through 1) an uncoupling reaction, as reported previously, and/or 2) disruption of IKKβ/NF-κB signaling.

Topics: Animals; Blotting, Western; Cell Culture Techniques; Cell Line; Electrophoretic Mobility Shift Assay; I-kappa B Kinase; Immunoprecipitation; Lipopolysaccharides; Lung; Macrophages; Mice; Mice, Inbred ICR; Naphthoquinones; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase Type II; Signal Transduction; Transfection

To determine how endogenously secreted beta-amyloid 42 (Abeta42) aggregates regulate synaptic functions, we examined effects of Abeta42 at the neuromuscular junction of Drosophila larvae. Voltage-clamp recordings of synaptic transmission and optical analysis of vesicle recycling at presynaptic terminals show that expression of Abeta42 in neurons leads to a reduction of neurotransmitter release. However, expression of Abeta42 in postsynaptic muscle cells enhanced neurotransmitter release. Both effects are neutralized by Abeta antibody, suggesting a role for secreted Abeta42 peptides. Application of exogenously prepared Abeta42 oligomers leads to a reduction in synaptic responses, whereas mixed Abeta42 aggregates with mainly fibrils elicit an opposite effect by increasing synaptic transmission. Further analysis of long-term depression (LTD) confirms differential effects of different Abeta42 aggregates. Taken together, our data suggest that Abeta42 is secreted from neurons primarily as oligomers that inhibit neurotransmitter release and exert no effect on LTD. Whereas larger-sized aggregates, possibly fibrils, are major components secreted from muscle cells, which enhance synaptic transmission and LTD. Thus, different types of cells may secrete distinct forms of Abeta42 aggregates, leading to different modulation of synaptic functions.

Topics: Amyloid beta-Peptides; Animals; Animals, Genetically Modified; Apigenin; Drosophila melanogaster; Exocytosis; Humans; Larva; Long-Term Synaptic Depression; Muscle, Skeletal; Naphthoquinones; Neuromuscular Junction; Neurons; Patch-Clamp Techniques; Peptide Fragments; Synapses; Synaptic Transmission

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

Topics: Adaptor Proteins, Signal Transducing; Animals; Asthma; Drug Delivery Systems; Mice; Naphthoquinones; Rats

Naphthalene is considered by the US Environmental Protection Agency to be a carcinogenic compound based on inhalation studies in rats. The primary metabolite of naphthalene is naphthalene 1,2-arene oxide. This unstable intermediate can lead to formation of 1-naphthol and naphthalene-1,2-dihydrodiol. Secondary metabolites include 1,2-dihydroxynaphthalene (1,2-DHN), which can be further oxidized to 1,2-naphthoquinone (1,2-NQ). Based on the metabolism of naphthalene and its similarity to the metabolic activation of carcinogenic natural estrogens, synthetic estrogens and benzene, we hypothesize that naphthalene is activated to initiate cancer by reaction of 1,2-NQ with DNA to form the depurinating adducts 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua. These adducts were synthesized by reaction of 1,2-NQ with Ade or dG in acetic acid/water/DMF (1:1:1). 1,2-NQ was reacted with DNA, and the depurinating 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua adducts were analyzed by ultraperformance liquid chromatography/tandem mass spectrometry and HPLC with electrochemical detection. After the reaction of 1,2-NQ with DNA, the N3Ade and N7Gua adducts were found. Similarly, when 1,2-DHN was activated by tyrosinase in the presence of DNA, higher amounts of the N3Ade and N7Gua adducts were detected. These same adducts were also formed when 1,2-DHN was activated by prostaglandin H synthase or 3-methylcholanthrene-induced rat liver microsomes in the presence of DNA. These depurinating adducts are analogous to those obtained from the ortho-quinones of natural estrogens, synthetic estrogens and benzene. These results suggest that reaction of ortho-quinones with DNA by 1,4-Michael addition is a general mechanism of weak carcinogenesis that occurs with naphthalene and a number of other aromatic compounds.

Topics: Adenine; Carcinogens; DNA Adducts; Guanine; Kinetics; Molecular Structure; Naphthalenes; Naphthols; Naphthoquinones; Neoplasms

1,2-Naphthoquinone (1,2-NQ) is an atmospheric contaminant with electrophilic properties that allow it to react readily with protein thiol groups such as those found on the cAMP response element-binding protein (CREB), a transcription factor with conserved cysteine residues that regulate DNA binding. In the present study, we explored the possibility that the interaction of 1,2-NQ with CREB will affect its activity, resulting in down-regulation of gene expression. With bovine aortic endothelial cells (BAECs) and a cell-free system, 1,2-NQ was found to covalently bind to CREB, and inhibit its DNA binding activity under conditions that were blocked by dithiothreitol. CRE-dependent luciferase activity and the down-regulation of Bcl-2 expression were suppressed by exposure of BAECs to 1,2-NQ. This phenomenon was not seen with the hydrocarbon, naphthalene, which lacks any electrophilic properties. The results indicate that CREB is a molecular target for 1,2-NQ which through irreversible binding, inhibits the function of this transcription factor.

Topics: Air Pollutants; Animals; Cattle; Cells, Cultured; Cyclic AMP Response Element-Binding Protein; DNA; Down-Regulation; Endothelium, Vascular; Naphthoquinones; Proto-Oncogene Proteins c-bcl-2; Transcription, Genetic

1,2-Naphthoquinone (1,2-NQ), an atmospheric contaminant, causes the contraction of guinea pig trachea through the activation of epidermal growth factor receptor (EGFR) by inhibiting protein-tyrosine phosphatases (PTPs). Phosphorylation of EGFR is negatively regulated by PTPs, but details of the mechanism by which 1,2-NQ inhibits PTPs have not been elucidated. Results described in this report demonstrate that 1,2-NQ forms covalent bonds with PTP1B after exposure to human epithelial A431 cells. In this study, a concentration-dependent phosphorylation of EGFR was found to be coupled to the reduction of PTP activity in the cells. The reduction in PTP activity was due to the irreversible modification of PTP1B, and when PTP1B was overexpressed by the cells, the 1,2-NQ-mediated EGFR phosphorylation was suppressed. Studies with purified PTP1B and 1,2-NQ showed that the reduction in enzyme activity was due to a nucleophilic attack by the quinone on the enzyme, to form covalent bonds. Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry analysis and mutation experiments revealed that PTP1B inactivation was primarily due to covalent attachment of the quinone to Cys-121 of the enzyme, with binding to His-25 and Cys-215 as well. Collectively, the results show that covalent attachment of 1,2-NQ to PTP1B is at least partially responsible for the reduction of PTP activity, which leads to prolonged transactivation of EGFR in the cells.

Topics: Cell Line, Tumor; ErbB Receptors; Humans; Immunoprecipitation; Models, Chemical; Mutagenesis; Mutation; Naphthoquinones; Phosphorylation; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Quinones; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Transcriptional Activation; Transfection

This study was designed to characterize naphthalene metabolism in Polaromonas naphthalenivorans CJ2. Comparisons were completed using two archetypal naphthalene-degrading bacteria: Pseudomonas putida NCIB 9816-4 and Ralstonia sp. strain U2, representative of the catechol and gentisate pathways, respectively. Strain CJ2 carries naphthalene catabolic genes that are homologous to those in Ralstonia sp. strain U2. Here we show that strain CJ2 metabolizes naphthalene via gentisate using respirometry, metabolite detection by GC-MS and cell-free enzyme assays. Unlike P. putida NCIB 9816-4 or Ralstonia sp. strain U2, strain CJ2 did not grow in minimal medium saturated with naphthalene. Growth assays revealed that strain CJ2 is inhibited by naphthalene concentrations of 78 microM (10 p.p.m.) and higher, and the inhibition of growth is accompanied by the accumulation of orange-coloured, putative naphthalene metabolites in the culture medium. Loss of cell viability coincided with the appearance of the coloured metabolites, and analysis by HPLC suggested that the accumulated metabolites were 1,2-naphthoquinone and its unstable auto-oxidation products. The naphthoquinone breakdown products accumulated in inhibited, but not uninhibited, cultures of strain CJ2. Furthermore, naphthalene itself was shown to directly inhibit growth of a regulatory mutant of strain CJ2 that is unable to metabolize naphthalene. These results suggest that, despite being able to use naphthalene as a carbon and energy source, strain CJ2 must balance naphthalene utilization against two types of toxicity.

Topics: Chromatography, High Pressure Liquid; Comamonadaceae; Culture Media; Dioxygenases; Gas Chromatography-Mass Spectrometry; Gentisates; Mutation; Naphthalenes; Naphthoquinones; Oxygen Consumption

1,2-Naphthoquinone (1,2-NQ) has recently been identified as an environmental quinone in diesel exhaust particles (DEP) and atmospheric PM2.5. We have found that this quinone is capable of causing a concentration-dependent contraction of tracheal smooth muscle in guinea pigs with EC50 value of 18.7 microM. The contraction required extracellular calcium and was suppressed by L-type calcium channel blockers nifedipine and diltiazem. It was found that 1,2-NQ activated phospholipase A2 (PLA2)/lipoxygenase (LO)/vanilloid receptor (VR1) signaling. Additionally, 1,2-NQ was capable of transactivating protein tyrosine kinases (PTKs) such as epidermal growth factor receptor (EGFR) in guinea pig trachea, suggesting that phosphorylation of PTKs contributes to 1,2-NQ-induced tracheal contraction. Consistent with this notion, this action was blocked by the PTKs inhibitor genistein and the EGFR antagonist PD153035, indicating that contraction was, at least in part, attributable to PTKs phosphorylation that activates VR1, resulting in increased intracellular calcium content in the smooth muscle cells.

Topics: Air Pollutants; Animals; Calcium Channels, L-Type; Dose-Response Relationship, Drug; Guinea Pigs; In Vitro Techniques; Lipoxygenase; Male; Muscle Contraction; Muscle, Smooth; Naphthoquinones; Phospholipases A; Phospholipases A2; Phosphorylation; Protein-Tyrosine Kinases; Signal Transduction; Trachea; TRPV Cation Channels

Diesel exhaust particles contain redox-active quinones, such as 9,10-phenanthraquinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ), which act as potent electron acceptors, thereby altering electron transfer tgljoint @/Set Line Joint Styleon proteins. We have previously found that 9,10-PQ inhibits constitutive nitric oxide synthase (NOS) activity, by shunting electrons away from NADPH on the cytochrome P450 reductase domain of NOS, and thus suppresses acetylcholine (Ach)-induced vasorelaxation in the aortic ring. However, the effect of 1,2-NQ on endothelial NOS (eNOS) activity is still poorly understood. With the membrane fraction of cultured bovine aortic endothelial cells, we found that 1,2-NQ was a potent inhibitor of eNOS with an IC50 value of 1.4 microM, whereas trans-1,2-dihydroxy-1,2-dihydronaphthalene (1,2-DDN), a redox-negative naphthalene analog of 1,2-NQ, did not show such an inhibitory action. Although 1,2-DDN (5 microM) did not affect Ach-mediated vasorelaxation, 1,2-NQ caused a significant suppression of Ach-induced endothelium-dependent vasorelaxation in the aortic ring. However, 1,2-NQ did not affect sodium nitroprusside-induced endothelium-independent vasorelaxation. These results suggest that 1,2-NQ is an environmental quinone that inhibits eNOS activity, thereby disrupting NO-dependent vascular tone.

Topics: Animals; Aorta, Thoracic; Cattle; Cells, Cultured; Endothelial Cells; Endothelium, Vascular; In Vitro Techniques; Male; Muscle, Smooth, Vascular; Naphthoquinones; Nitric Oxide Synthase Type III; Oxidation-Reduction; Rabbits; Vasodilation; Vehicle Emissions

The quenching of the triplets of 1,2-naphthoquinone (NQ) and 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS) by various electron and H-atom donors was investigated by laser flash photolysis measurement in acetonitrile and benzene. The results showed that the reactivities and configurations of 3NQ* (3NQS*) are governed by solvent polarity. All the quenching rate constants (kq) measured in benzene are larger than those in acetonitrile. The SO3Na substituent at the C-4 position of NQS makes 3NQS* more reactive than 3NQ* in electron/H-atom transfer reactions. Large differences of kq values were discovered in H-atom transfer reactions for alcohols and phenols, which can be explained by different H-abstraction mechanisms. Detection of radical cations of amines/anilines in time-resolved transient absorption spectra confirms an electron transfer mechanism. Triplets are identified as precursors of formed radical anions of NQ and NQS in photoinduced reactions. The dependence of electron transfer rate constants on the free energy changes (DeltaG) was treated by using the Rehm-Weller equation. For the four anilines with different substituents on the para or meta position of amidocyanogen, good correlation between log kq values with Hammett sigma constants testifies the correctness of empirical Hammett equation. Charge density distributions, adiabatic ionization/affinity potentials and redox potentials of NQ (NQS) and some quenchers were studied by quantum chemistry calculation.

Topics: Electrons; Hydrogen; Lasers; Models, Chemical; Naphthoquinones; Oxygen; Photochemistry; Photolysis; Sensitivity and Specificity; Spectrophotometry; Ultraviolet Rays

Protein tyrosine phosphatase-1B (PTP1B) has been demonstrated to play a key role in the negative signalling pathway of insulin. Potent and orally active PTP1B inhibitors are considered to be promising pharmacological agents for the treatment of type-2 diabetes and resistance to weight gain. CoMSIA studies have been preformed on 1,2-naphthoquinone derivatives that are reported to be potential non-peptidic inhibitors of PTP1B. For the selection of dataset to develop the model, the reported molecules were subjected to property filters and segregated into training and test set. As the crystal structure of PTP1B-naphthoquinone derivative is not known, the most active molecule was subjected to simulated annealing dynamics method and the lowest energy conformer was reminimised and considered as the bioactive conformation. Database-inertial alignment was followed for aligning the molecules. Different CoMSIA models were built to get the best related field.

Topics: Enzyme Inhibitors; Inhibitory Concentration 50; Models, Molecular; Molecular Structure; Naphthoquinones; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases; Structure-Activity Relationship

We demonstrate for the first time that agglomerates of multiwalled carbon nanotubes (MWCNTs) can be formed in which the binder in the agglomerate is itself a redox-active molecular solid. Two separate agglomerates were formed by dissolving 9,10-phenanthraquinone (PAQ) or 1,2-napthaquinone (NQ) in acetone together with MWCNTs and adding an excess of aqueous solution to cause precipitation of agglomerates, approximately 10 microns in dimension, which consist of bundles of nanotubes running into and throughout the amorphous molecular solid that binds the agglomerate together. The nature of this structure, when immobilised on a substrate electrode and in contact with aqueous electrolyte solutions, gives rise to many three-phase boundaries, electrolyte|agglomerate|conductor, which is advantageous to the solid-state analytical electrochemistry of such a material as it imparts a larger electroactive surface area than other modified carbon electrodes. The two agglomerates each gave a voltammetrically measurable response to changes in pH; when abrasively immobilised on a basal plane pyrolitic graphite electrode a plot of peak potential against pH produced a linear response for both MWCNT-PAQ and MWCNT-NQ agglomerates over the pH range pH 1-12 and over the temperature range 20-70 degrees C.

Topics: Chemistry, Physical; Electrochemistry; Electrons; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Models, Molecular; Nanotubes, Carbon; Naphthoquinones; Oxidation-Reduction; Phenanthrenes; Temperature

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

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

A new series of 1,2-naphthoquinone derivatives was synthesized by various synthetic methods and evaluated for their ability to inhibit protein tyrosine phosphatase 1B (PTP1B). 1,2-Naphthoquinone derivatives with substituent at R(4) position showed submicromolar inhibitory activity, and compound 24 demonstrated 10- to 60-fold selectivity against the tested phosphatases. Also, several 4-aryl-1,2-naphthoquinone derivatives with substituents at R(3), R(6), R(7), or/and R(8) showed submicromolar inhibitory activity and good plasma stability.

Topics: Enzyme Inhibitors; Humans; Hypoglycemic Agents; Inhibitory Concentration 50; Naphthoquinones; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases; Stereoisomerism; Structure-Activity Relationship

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

An injection of 1,2-naphthoquinone (NQ) into the anterior chamber of mouse eye produces anterior cortical cataract. It was previously shown by histology that mitochondria in lens epithelial cells are the target of ocular drug toxicity. In this work we investigated NQ-induced cataract by closely examining morphological changes of mitochondria and other cellular organelles in the lens epithelium. Mitochondria exhibited marked swelling in 2 hrs after NQ injection but restored the normal condensed configuration at 4.5 hrs. The nuclear chromatin showed condensation at 2 hrs and returned to the normal appearance at 4.5 hrs. This was unexpected because the lens at 4.5 hrs was cataractous due to vacuole formation in fiber cell layers. The result indicates that, although lens epithelial mitochondria are the target of NQ toxicity, cataract begins to develop before mitochondria and other subcellular organelles become totally dysfunctional. At 1 week after NQ injection, most mitochondria disintegrated and the fragmented chromatin appeared to leak out through the ruptured nuclear membrane. SOD injected with NQ significantly delayed the onset of cataract and protected lens epithelial cells. A second SOD injection further delayed cataract development.

Topics: Animals; Cataract; Lens, Crystalline; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron; Mitochondria; Naphthoquinones; Superoxide Dismutase

N-acetyl-p-benzoquinone imine (NAPQI), a semiquinone metabolite of acetaminophen, produces cataract in mice. Naphthalene is biotransformed to the cataractogenic metabolite 1,2-naphthoquinone (NQ). Intracameral injection of NAPQI elicits a rapid increase in free intracellular Ca2+ in the lens epithelium and calpain activation before lens opacification begins. In order to test whether the cellular response is a common feature of quinone-induced cataracts, we injected in this work 1,2-naphthoquinone (NA) in the anterior chamber of mouse eye and followed cellular responses in the lens prior to opacity development. A marked rise in free intracellular Ca2+ in the lens epithelium and concurrent activation of calpain were observed within 1 hr after NQ injection preceding lens opacity development. These results support the suggestion that Ca2+ release and calpain activation are involved in the mechanism of quinone-induced cataractogenesis.

Topics: Animals; Anterior Chamber; Calcium; Calpain; Cataract; Epithelial Cells; Glycoproteins; Lens, Crystalline; Male; Mice; Mice, Inbred C57BL; Microscopy, Confocal; Naphthoquinones; Oligopeptides

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

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

Glutathione S-transferase (GST) plays an important role in the detoxifications of foreign electrophiles. Two GSTs of class mu from guinea pig lens were purified with Sephacryl S-100 gelfiltration, S-Hexyl glutathione Agarose affinity and Q-Sepharose anion exchange chromatographies. These GSTs (GST-A and B) showed similar relative molecular masses of 22.9 and 22.5 kDa, respectively. Two protein bands which crossreacted with anti GSTYb1 (GST 3-3) were detected in lens cytosolic crude extract on Western blotting and they showed Mrs corresponding to the purified enzymes. These GSTs showed a strong resistance against H2O2, 1,2-naphthoquinone and superoxide anion consistent with the other GSTs in class mu from animal tissues.

Topics: Animals; Blotting, Western; Enzyme Inhibitors; Enzyme Stability; Glutathione Transferase; Guinea Pigs; Hydrogen Peroxide; Lens, Crystalline; Naphthoquinones; Substrate Specificity; Superoxides

Electrochemical methods have been widely used to monitor physiologically important molecules in biological systems. This report describes the first application of the scanning electrochemical microscope (SECM) to probe the redox activity of individual living cells. The possibilities of measuring the rate and investigating the pathway of transmembrane charge transfer are demonstrated. By this approach, significant differences are detected in the redox responses given by nonmotile, nontransformed human breast epithelial cells, breast cells with a high level of motility (engendered by overexpression of protein kinase Calpha), and highly metastatic breast cancer cells. SECM analysis of the three cell lines reveals reproducible differences with respect to the kinetics of charge transfer by several redox mediators.

Topics: Animals; Breast; Breast Neoplasms; Cattle; Cell Line; Cell Membrane; Cell Movement; Cells, Immobilized; Electrochemistry; Epithelial Cells; Female; Humans; Isoenzymes; Microscopy, Electron, Scanning; Naphthoquinones; Neoplasm Metastasis; Oxidation-Reduction; Protein Kinase C; Protein Kinase C-alpha; Transfection; Tumor Cells, Cultured; Vitamin K

The oxidation of naphthalene-1,2-dihydrodiol (ND) to o-naphthoquinone (NQ) in the lens is believed to be responsible for the formation of cataracts in naphthalene-fed rats. Studies using either recombinant rat lens (RLAR) or human muscle aldose reductase (HMAR) incubated in vitro with ND in the presence of NAD(P) verified that aldose reductase (EC 1.1.1.21) is the dihydrodiol dehydrogenase that catalyzes the oxidation of ND to NQ. Kinetic studies of Vmax/Km indicated that RLAR catalyzes the NAD-dependent oxidation of ND with an optimal pH of 9.0. The corresponding activity of HMAR was lower than that of rat enzyme. The metabolite produced by the incubation of RLAR with ND in the presence of 2-mercaptoethanol and NAD in 20 mM phosphate buffer, pH 7.5, was isolated by C18 reversed-phase high-performance liquid chromatography. The elution profile showed the formation of a new peak that was identical with a peak generated when NQ was incubated under the same condition. The metabolite in both peaks was identified as 4-(2-hydroxyethylsulfanyl)-1, 2-dihydro-1,2-naphthalenedione (HNQ) by 1H and 13C NMR analyses using homonuclear correlation spectroscopy, heteronuclear multiple quantum coherence, and heteronuclear shift correlations via multiple bond connectivities as well as infrared analysis. HNQ is readily autoxidized to 2,3-dihydro-1-oxa-4-thia-9,10-phenanthrenedione. The stoichiometry of 1:1 between the consumption of ND and the formation of NADH for the formation of HNQ implies that rat lens aldose reductase catalyzes a 2e- oxidation of ND to yield the corresponding ketol, which is autoxidized to NQ.

Topics: Aldehyde Reductase; Animals; Cataract; Cells, Cultured; Disease Models, Animal; Humans; Lens, Crystalline; Naphthols; Naphthoquinones; Oxidation-Reduction; Rats

The effects of aldose reductase inhibitors on lens protein modifications induced by naphthalene-1,2-dihydrodiol were investigated in vitro to confirm the role of aldose reductase on naphthalene cataract formation. HPLC analysis of naphthalene-1, 2-dihydrodiol incubated with aldose reductase and NAD+indicated the formation of a metabolite peak corresponding to 1,2-naphthoquinone. Soluble proteins from rat lenses prepared by gel filtration of crude lens extracts through Sephadex PD-10, incubated with naphthalene-1, 2-dihydrodiol in the presence of NAD+displayed an absorbance ca 450 nm and their spectra were essentially identical to those of 1, 2-naphthoquinone-protein adducts. Similar spectra were also obtained from proteins isolated from the intact rat lens after in vitro incubation in medium containing naphthalene-1,2-dihydrodiol. The spectra obtained from lens proteins incubated with 1, 2-dihydroxynaphthalene were distinct from those of either naphthalene-1,2-dihydrodiol or 1,2-naphthoquinone. Aldose reductase inhibitors possessing either hydantoin or carboxylic acid groups prevented protein modification induced by naphthalene-1, 2-dihydrodiol but not protein modification induced by 1, 2-dihydroxynaphthalene or 1,2-naphthoquinone. Therefore, the metabolite formed from naphthalene-1,2-dihydrodiol by aldose reductase is 1,2-naphthoquinone. Lens proteins modified by naphthalene-1,2-dihydrodiol appear essentially identical to protein adducts formed with 1,2-naphthoquinone and their formation can be prevented by both hydantoin and carboxylic acid containing aldose reductase inhibitors.

Topics: Aldehyde Reductase; Animals; Cataract; Chromatography, High Pressure Liquid; Crystallins; Enzyme Inhibitors; Fluorenes; Hydantoins; Imidazoles; Imidazolidines; Lens, Crystalline; Naphthalenes; Naphthols; Naphthoquinones; Phthalazines; Rats; Spectrophotometry

Dihydrodiol dehydrogenase (DD) oxidizes naphthalene dihydrodiol to 1,2-dihydroxynaphthalene, which is immediately autoxidized to 1,2-naphthoquinone. Here we established a fluorometric assay for the enzyme, which is based on the conversion of 1,2-naphthoquinone to fluorescent compounds by reacting with ethylenediamine. The formed fluorescent compounds were synthetically identified as 6-(2-aminoethylamino)benzo[f]quinoxaline and 2,6- or 3,6-bis(2-aminoethylamino)benzo[f]quinoxaline, which showed the same fluorescence at 550 nm at an excitation wavelength of 420 nm. This method provides a 9000-fold increase in sensitivity over a currently available assay which measures the change in the absorbance of a cofactor, NADPH. Since this simple and sensitive method allowed many samples to be assayed simultaneously, we applied it to the analysis of multiple forms of DD, separated by an anion-exchange chromatography, from six human liver specimens.

Topics: Ethylenediamines; Female; Fluorometry; Humans; Liver; Male; Naphthoquinones; Oxidoreductases; Sensitivity and Specificity

The derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone-4-sulfonate (NQS) into solid-phase extraction cartridges (C18) is described. Optimum conditions were the use of carbonate-hydrogencarbonate buffer of pH 10, a 10 min reaction time at 25 degrees C and an NQS concentration of 9.6 x 10(-3) M. The accuracy and the precision of the method were tested. The results obtained with the proposed liquid-solid procedure were compared with those obtained with a traditional liquid-liquid extraction with hexane-ethyl acetate. The procedure was used to measure amphetamine in pharmaceutical and urine samples.

Topics: Amphetamine; Central Nervous System Stimulants; Humans; Methamphetamine; Naphthoquinones; Pharmaceutical Preparations; Spectrophotometry, Ultraviolet; Sulfonic Acids

The antimicrobial activity of tobramycin against anaerobic cultures of Escherichia coli was tested in the presence of various electron carriers. The presence of 2,6-dichlorophenol 4-indophenol (DCIP) significantly enhanced the killing efficacy of tobramycin. Only 0.003% of the initial cell population (i.e. 10(6) cfu/mL) remained viable after exposure for 10 h to the mixture of antibiotic (20 x MIC, i.e. 40 mg/L) and electron acceptor (10(-3) M), as compared with 9% of surviving organisms in the presence of tobramycin alone. Less synergy was obtained with p-benzoquinone and 1,2-naphthoquinone. Fumarate did not affect the efficiency of the antibiotic. The mixture of tobramycin and DCIP was ineffective against agar-entrapped bacteria which, like biofilm organisms, are subject to oxygen limitation.

Topics: 2,6-Dichloroindophenol; Anaerobiosis; Anti-Bacterial Agents; Benzoquinones; Biofilms; Electrons; Escherichia coli; Fumarates; Indicators and Reagents; Microbial Sensitivity Tests; Naphthoquinones; Tobramycin

Solid-phase extraction techniques were evaluated for the treatment of urine samples in the analysis of amphetamine and methamphetamine by normal-phase high-performance liquid chromatography with 1,2-naphthoquinone 4-sulphonate. Six different packing materials were tested, and the results obtained are compared with those obtained in a classical liquid-liquid extraction with n-hexane. Different clean-up eluents and the influence of pH of urine have been tested. The intra-day and inter-day precision, the accuracy of the method and the addition of beta-phenylethylamine as internal standard were also studied.

Topics: Amphetamine; Chromatography, High Pressure Liquid; Humans; Hydrogen-Ion Concentration; Indicators and Reagents; Methamphetamine; Naphthoquinones; Solvents; Substance Abuse Detection

The inhibitory effects of diesel exhaust particles (DEP) on superoxide dismutase (SOD) activity were examined in vitro because intratracheal administration of DEP to mice resulted in a suppression of the pulmonary enzyme activity (Sagai et al., Free Radic. Biol. Med. 14:37-47; 1993). Superoxide production, based on the reduction of cytochrome c, was suppressed considerably by the soluble fraction of mouse lung and by purified SOD from bovine erythrocytes, but the suppression was drastically diminished in the presence of methanol-extractable compounds of DEP. Inhibition of SOD by diethyldithiocarbamate was irreversible, but that by 1,2-naphthoquinone (1,2-NQ) and the methanol extract of DEP was removed by dialysis. Inhibition of superoxide mediated cytochrome c reduction by Tiron, a scavenging agent for superoxide, was blocked by the methanol extract and 1,2-NQ in a concentration-dependent manner. In contrast, addition of a large amount of SOD to the reaction mixture resulted in an almost complete disappearance of inhibitory action of not only 1,2-NQ but also the methanol extract. The existence of carbonyl compounds in the DEP was confirmed by thin-layer chromatography (TLC) with 2,4-dinitrophenylhydrazine reagent. Electron spin resonance (ESR) spectra of an incubation mixture of oxidized 1,2-dihydroxynaphthalene in the absence and presence of cytochrome c indicated a reaction between the semiquinone radical of 1,2-NQ and cytochrome c. These results indicate that the apparent reduction in SOD activity by DEP is due to the chemical reaction of superoxide with components like quinones, which reduce levels of superoxide.

Topics: Animals; Cattle; Cytochrome c Group; Ditiocarb; Erythrocytes; Escherichia coli; Fuel Oils; Lung; Methanol; Mice; Naphthoquinones; Superoxide Dismutase; Superoxides; Trachea

Porcine and bovine lens GSTs were compared in the stability against various oxidative stress which is a major factor of cataract formation in order to clarify the role of lens glutathione S-transferase (GST) and its relation to cataractogenesis. Class pi porcine lens GST was inactivated reversibly by biological disulfides, cystine and cystamine, and also inactivated by active oxygen species such as O2- generated through xanthine-xanthine oxidase system and H2O2. On the other hand, class mu bovine lens GST was insensitive to such applied oxidative stress. Furthermore, 1,2-naphthoquinone, which is a metabolite of naphthalene and an actual inducer of naphthalene cataract, strongly inactivated porcine lens GST though it did not affect bovine enzyme. Thus, porcine and bovine lens GSTs had different sensitivity to various oxidative stress which could induce cataract formation. The results suggest that the differential expression of GST isozymes among animals may explain the variation in the cataract formation caused by oxidative stress.

Topics: Animals; Cataract; Cattle; Cystamine; Cystine; Glutathione Transferase; Lens, Crystalline; Naphthoquinones; Reactive Oxygen Species; Swine

Polycyclic aromatic hydrocarbon (PAH) o-quinones are products of an NADP+ dependent oxidation of non-K-region trans-dihydrodiols catalyzed by dihydrodiol dehydrogenase (EC 1.3.1.20). Since these PAH o-quinones could be detoxified by non-enzymatic or enzymatic conjugation with cellular thiols, their reactivity with 2-mercaptoethanol, cysteine and glutathione (GSH) was examined by ion-pair reverse phase high pressure liquid chromatography (RP-HPLC). Second-order rate constants for the addition of these thiols to naphthalene-1,2-dione (NPQ) in water ranging from 4.9 x 10(3) - 1.1 x 10(4) min-1 M-1 and the reactions were complete within 10 min. When these reactions were conducted at near physiological pH (50 mM potassium phosphate buffer pH 7.0), the rate constants increased by 2-orders of magnitude. When benzo[a]pyrene-7,8-dione (BPQ) was substituted in these reactions the second-order rate constants decreased by 2-3 orders of magnitude and the reactions took several hours to reach completion. The decrease in reactivity can be explained by the presence of the bay region in BPQ. Methylation influenced the reactivity of PAH o-quinones with GSH and the following order of reactivity was observed: 7,12-dimethyl-benz[a]anthracene-3,4-dione (7,12-DMBAQ) >> 12-methyl-BAQ, 7-methyl-BAQ and BAQ >> BPQ. Of these quinones 7,12-dimethyl-BAQ was almost equi-reactive with NPQ. This suggests that methyl substitution in the bay and peri regions enhances reactivity with GSH. Using NPQ as a model for other PAH o-quinones, N-acetyl-L-cysteine, L-cysteine and GSH conjugates of NPQ were synthesized and characterized by [1H]- and [13C]NMR. Evidence for Michael type 1,4-addition products was obtained in which the resultant adduct could exist as either a catechol or o-quinone. By contrast, L-cysteine was able to form adducts via S- or N-attack and N-attack gave a purple p-iminoquinone. There was no evidence for the formation of bis-N-acetyl-L-cysteinyl-, bis-glutathionyl adducts or phenolic coupled products. The toxicity of thiol conjugates of NPQ remains to be explored.

Topics: Benzopyrenes; Chromatography, High Pressure Liquid; Cysteine; Glutathione; Hydrogen-Ion Concentration; Kinetics; Magnetic Resonance Spectroscopy; Mercaptoethanol; Molecular Structure; Naphthoquinones; Polycyclic Compounds; Quinones; Sulfhydryl Compounds

The response of the hexose monophosphate shunt (HMS) in organ-cultured guinea pig lens to 1,2-naphthoquinone and 5-hydroxy-1,4-naphthoquinone (juglone) has been investigated. Both these compounds, which are substrates of guinea pig lens zeta-crystallin (NADPH:quinone oxidoreductase), were found to cause increases in the rate of 14CO2 production from 1-14C-labelled glucose. Exposure of lenses to 15 microM 1,2-naphthoquinone or 20 microM juglone yielded 5.9- and 7-fold stimulation of HMS activity, respectively. Unlike hydrogen peroxide-induced stimulation of HMS activity, these effects were not abolished by preincubation with the glutathione reductase inhibitor, 1,3-bis(2-chloroethyl)-1 nitrosourea (BCNU). While hydrogen peroxide produced substantial decrements in lens glutathione (GSH) levels, incubation with quinones was not associated with a similar reduction in GSH concentration. Protein-bound NADPH content in quinone-exposed guinea pig lenses was decreased, with a concomitant increase in the amounts of free NADP+. This finding supported the involvement of zeta-crystallin bound NADPH in the in vivo enzymic reduction of quinones. Hydrogen peroxide, on the other hand, caused decreases in the level of free NADPH alone, serving to confirm our earlier inference that quinone stimulated increases in the guinea pig lens HMS could be mediated through zeta-crystallin NADPH:quinone oxidoreductase activity.

Topics: Animals; Carmustine; Crystallins; Dose-Response Relationship, Drug; Guinea Pigs; Hydrogen Peroxide; Lens, Crystalline; NADP; Naphthoquinones; Organ Culture Techniques; Pentose Phosphate Pathway; Rats; Rats, Inbred Strains

We have examined the mercapturic acid pathway of the cataractous rabbit lens following induction by naphthalene as an oxidative foreign substance. 1,2-Naphthoquinone, which is formed in the eye from naphthalene diol and other naphthalene derivatives by a combination of enzymic and non-enzymic reactions, readily oxidizes GSH and GSH S-transferase [EC 2.5.1.18] in the lens scavenging system. 1,2-Naphthoquinone appeared in the rabbit aqueous humor after 8 h, and showed a maximum level in the lens 24 h after naphthalene administration, with marked accumulation in the lens nucleus. At the same time, the GSH level and GSH S-transferase activity in the lens decreased after 4 h, and lens opacification appeared 7 days after naphthalene administration. Furthermore, we identified the naphthalene metabolite, N-acetyl-S-(1,2-dihydro-2-hydroxynaphthyl) cysteine, in the lens of rabbit after naphthalene administration and in an in vitro experiment on lens homogenate using gas chromatography-mass spectrometry (GC-MS). This compound is an intermediate of the mercapturic acid pathway, and indicates that naphthalene derivatives are metabolized through the mercapturic acid pathway which acts as a scavenging system in the lens.

Topics: Acetylcysteine; Animals; Aqueous Humor; Cataract; Female; Gas Chromatography-Mass Spectrometry; Glutathione; Glutathione Transferase; Lens, Crystalline; Naphthalenes; Naphthoquinones; Rabbits

Topics: Animals; Copying Processes; Female; Guinea Pigs; Humans; Indenes; Industrial Waste; Male; Maximum Allowable Concentration; Naphthoquinones; Rats; Water Pollutants; Water Pollutants, Chemical; Water Supply

Topics: Amines; Chemical Phenomena; Chemistry; Desipramine; Naphthoquinones; Structure-Activity Relationship

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

Incorporation of 32P from [gamma-32P]ATP into endogenous proteins, added histone and the copolymers Glu 80 Tyr 20 by rat liver plasma membranes was markedly increased by several naphthoquinones, including menadione. This stimulation was most marked with Glu 80 Tyr 20, has an absolute requirement for either dithiothreitol or reduced glutathione, and was inhibited by superoxide dismutase, catalase, and desferrioxamine to varying degrees depending on the quinones used. Their effectiveness in stimulating the apparent tyrosine-specific protein phosphorylation correlated with the rates of DTT-dependent redox cycling measured by oxygen consumption. Increased protein phosphorylation was also seen with particulate fractions isolated from hepatocytes incubated with quinones. A free radical-mediated mechanism is suggested for the quinone stimulation of protein phosphorylation.

Topics: Adenosine Triphosphate; Animals; Benzoquinones; Cell Membrane; Deferoxamine; Free Radicals; Hydroquinones; Liver; Naphthoquinones; Oxidation-Reduction; Oxygen; Oxygen Consumption; Protein-Tyrosine Kinases; Quinones; Rats; Structure-Activity Relationship; Superoxide Dismutase; Vitamin K

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

1-Naphthol was metabolized by the polyphenol oxidase, tyrosinase, primarily to 1,2-naphthoquinone and to small amounts of 1,4-naphthoquinone as well as to covalently bound products. The inhibition of covalent binding by ethylenediamine, which reacts specifically with 1,2-naphthoquinone but not 1,4-naphthoquinone, suggested that most of the covalent binding was due to 1,2-naphthoquinone or a metabolite of similar structure. The activation by tyrosinase of 1-naphthol to covalently bound products suggested that it may alter the reaction kinetics of the enzyme. This was investigated by studying the effects of 1-naphthol on the tyrosinase-catalysed oxidation of 4-hydroxyanisole. Preincubation of tyrosinase with 1-naphthol increased the lag period of the oxidation of 4-hydroxyanisole, which may be due to a decrease in the amount of active enzyme, as well as to a reaction of 1-naphthol with 3,4-anisylquinone, an oxidation product of 4-hydroxyanisole. The metabolic activation of 1-naphthol by tyrosinase to covalently bound species suggests that 1-naphthol or a structurally related derivative may be of potential therapeutic application in the treatment of cells high in tyrosinase activity, such as certain melanomas.

Topics: Anisoles; Biotransformation; Catalysis; Catechol Oxidase; Chromatography, High Pressure Liquid; Kinetics; Monophenol Monooxygenase; Naphthols; Naphthoquinones; Oxidation-Reduction; Protein Binding; Spectrophotometry

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

Topics: Antibodies; Humans; Naphthoquinones

Topics: Naphthoquinones