ascorbic-acid and imidazole

Alzheimer's disease (AD) possesses a complex pathogenetic mechanism. Nowadays, multitarget agents are considered to have potential in effectively treating AD via triggering molecules in functionally complementary pathways at the same time. Here, based on the screening (∼1400 compounds) against neuroinflammation, an imidazolylacetophenone oxime ether (IOE) was discovered as a novel hit. In order to obtain SARs, a series of imidazolylacetophenone oxime derivatives were constructed, and their C=N bonds were confirmed as the Z configuration by single crystals. These derivatives exhibited potential multifunctional neuroprotective effects including anti-neuroinflammatory, antioxidative damage, metal-chelating, inhibition of acetylcholinesterase (AChE) properties. Among these derivatives, compound 12i displayed the most potent inhibitory activity against nitric oxide (NO) production with EC

Topics: Acetophenones; Acetylcholinesterase; Animals; Biphenyl Compounds; Cell Line; Cyclooxygenase 2; Dose-Response Relationship, Drug; Drug Discovery; Electrophorus; Enzyme Inhibitors; Humans; Imidazoles; Lipopolysaccharides; Mice; Molecular Structure; Neuroprotective Agents; Nitric Oxide; Oximes; Picrates; Rats; Structure-Activity Relationship

In this study, we have designed and synthesized 2-((5-acetyl-1-(phenyl)-4-methyl-1H-imidazol-2-yl)thio)-N-(4-((benzyl)oxy)phenyl) acetamide derivatives. Antimicrobial activities of all the imidazole derivatives have been examined against Gram-positive and Gram-negative bacteria and results showed that the conjugates have appreciable antibacterial activity. Besides, several analogous were evaluated for their in vitro antiresistant bacterial strains such as Extended-spectrum beta-lactamases (ESBL), Vancomycin-resistant Enterococcus (VRE), and Methicillin-resistant Staphylococcus aureus (MRSA). The SAR revealed that the 12l compound resulted in potency against all bacterial strains as well as ESBL, VRE, and MRSA strains. Lipinski's rule of five, and ADME studies were preformed for all the synthesized compounds with Staphylococcus aureus dihydropteroate synthase (saDHPS) protein (PDB ID: 6CLV) and were found standard drug-likeness properties of conjugates. Moreover, the binding mode of the ligands with the protein study has been examined by molecular docking and results are quite promising. Besides, all the analogous were tested for their in vitro antituberculosis, antimalarial, and antioxidant activity.

Topics: Anti-Bacterial Agents; Dihydropteroate Synthase; Dose-Response Relationship, Drug; Drug Design; Enzyme Inhibitors; Imidazoles; Ligands; Microbial Sensitivity Tests; Molecular Structure; Staphylococcus aureus; Structure-Activity Relationship; Vancomycin-Resistant Enterococci

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with multiple factors associated with its pathogenesis. Our strategy against AD involves design of multi-targeted 2-substituted-4,5-diphenyl-1H-imidazole analogues which can interact and inhibit AChE, thereby, increasing the synaptic availability of ACh, inhibit BuChE, relieve induced oxidative stress and confer a neuroprotective role. Molecular docking was employed to study interactions within the AChE active site. In silico ADME study was performed to estimate pharmacokinetic parameters. Based on computational studies, some analogues were synthesized and subjected to pharmacological evaluation involving antioxidant activity, toxicity and memory model studies in animals followed by detailed mechanistic in vitro cholinesterase inhibition study. Amongst the series, analogue 13 and 20 are the most promising multi-targeted candidates which can potentially increase memory, decrease free radical levels and protect neurons against cognitive deficit.

Topics: Acetylcholinesterase; Alzheimer Disease; Animals; Butyrylcholinesterase; Cholinesterase Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Electrophorus; Female; Horses; Imidazoles; Male; Maze Learning; Memory Disorders; Mice; Molecular Structure; Neuroprotective Agents; Structure-Activity Relationship

In the present work, 1-(5-methyl-2-phenyl-1H-imidazol-4-yl)ethanone 1 was prepared and used as a precursor for the synthesis of new thiazole, arylidiene and coumarin derivatives. The antimicrobial, antioxidant, anti-hemolytic, and cytotoxic activities of new compounds have been screened. Compound 12 showed an excellent antibacterial activity for all the tested bacteria with minimal inhibitory concentration (MIC) ranged between 21.9 and 43.8 μg/mL. While, compounds 2, 8 and 10a were the best antioxidant reagents using the DPPH method. Compounds 6a and 10b proved to exhibit potent antioxidative activity as reflected in the ability to inhibit lipid per-oxidation in rat brain and kidney homogenates and rate erythrocyte hemolysis. Compounds 6a proved to have the highest cytotoxic activity (81.9%) followed by 2, 6c, 7b and 12 using in vitro Ehrlich ascites assay. The details synthetic methods, spectroscopic data and biological results are recorded.

Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Antioxidants; Bacteria; Cell Proliferation; Drug Screening Assays, Antitumor; Erythrocytes; Hemolysis; Heterocyclic Compounds; Imidazoles; Microbial Sensitivity Tests; Molecular Structure; Rats; Stereoisomerism; Structure-Activity Relationship

It is hypothesized that metal ion-mediated adsorption of phosphorylated peptides on stationary phases of LC-columns is the major cause for their frequently observed poor detection efficiency in LC-MS. To study this phenomenon in more detail, sample solutions spiked with metal ion-mobilizing additives were analyzed by reversed phase μLC-ICP-MS or nanoLC-ESI-MS. Using μLC-ICP-MS, metal ions were analyzed directly as atomic ions. Using electrospray ionization, either metal ion chelates or phosphopeptide standard mixtures injected in subpicomole amounts were analyzed. Deferoxamine, imidazole, ascorbate, citrate, EDTA, and the tetrapeptide pSpSpSpS were tested as sample additives for the interlinked purposes of metal ion-mobilization and improvement of phosphopeptide recovery. Iron probably represents the major metal ion contamination of reversed phase columns. Based on the certified iron level in LC-grade solvents, a daily metal ion load of >10 pmol was estimated for typical nanoLC flow rates. In addition, phosphopeptide fractions from IMAC columns were identified as source for metal ion contamination of the LC column, as demonstrated for Ga(3+)-IMAC. The three metal ion-chelating additives, EDTA, citrate and pSpSpSpS, were found to perform best for improving the LC recovery of multiply phosphorylated peptides injected at subpicomole amounts. The benefits of metal ion-mobilizing LC (mimLC) characterized by metal ion complexing sample additives is demonstrated for three different instrumental setups comprising (a) a nanoUPLC-system with direct injection on the analytical column, (b) a nanoLC system with inclusion of a trapping column, and (c) the use of a HPLC-Chip system with integrated trapping and analytical column.

Topics: Adsorption; Aluminum; Amino Acid Sequence; Ascorbic Acid; Chromatography, Reverse-Phase; Coordination Complexes; Deferoxamine; Imidazoles; Iron; Molecular Sequence Data; Nanotechnology; Peptide Fragments; Phosphoproteins; Phosphorus; Reference Standards; Titanium

Maize malic enzyme was rapidly inactivated by micromolar concentrations of cupric nitrate in the presence of ascorbate at pH, 5.0. Ascorbate or Cu2+ alone had no effect on enzyme activity. The substrate L-malate or NADP individually provided almost total protection against Cu2+-ascorbate inactivation. The loss of enzyme activity was accompanied by cleavage of the enzyme. The cleaved peptides showed molecular mass of 55 kDa, 48 kDa, 38 kDa, and 14 kDa. Addition of EDTA, histidine and imidazole provided protection. The results of protection experiments with sodium azide, DABCO and catalase suggested that reactive oxygen species were generated resulting in loss of enzyme activity. This was further supported by experiments showing that the rate of enzyme inactivation was higher in D2O than in water. It is suggested that maize malic enzyme is modified by reactive oxygen species like singlet oxygen and H2O2 generated by Cu2+-ascorbate system and the modified amino acid residue(s) may be located at or near the substrate-binding site of the enzyme.

Topics: Amino Acids; Ascorbic Acid; Catalase; Copper; Deuterium Oxide; Edetic Acid; Histidine; Hydrogen Peroxide; Hydrogen-Ion Concentration; Imidazoles; Malates; NADP; Oxygen; Piperazines; Reactive Oxygen Species; Zea mays

Cytochrome b(561) mediates equilibration of the ascorbate/semidehydroascorbate redox couple across the membranes of secretory vesicles. The cytochrome is reduced by ascorbic acid and oxidized by semidehydroascorbate on either side of the membrane. Treatment with diethyl pyrocarbonate (DEPC) inhibits reduction of the cytochrome by ascorbate, but this activity can be restored by subsequent treatment with hydroxylamine, suggesting the involvement of an essential histidine residue. Moreover, DEPC inactivates cytochrome b(561) more rapidly at alkaline pH, consistent with modification of a histidine residue. DEPC does not affect the absorption spectrum of cytochrome b(561) nor does it change the midpoint reduction potential, confirming that histidine modification does not affect the heme. Ascorbate protects the cytochrome from inactivation by DEPC, indicating that the essential histidine is in the ascorbate-binding site. Further evidence for this is that DEPC treatment inhibits oxidation of the cytochrome by semidehydroascorbate but not by ferricyanide. This supports a reaction mechanism in which ascorbate loses a hydrogen atom by donating a proton to histidine and transferring an electron to the heme.

Topics: Animals; Ascorbic Acid; Binding Sites; Cattle; Chromaffin Granules; Cytochrome b Group; Diethyl Pyrocarbonate; Enzyme Inhibitors; Formates; Histidine; Hydrogen-Ion Concentration; Imidazoles; Intracellular Membranes; Kinetics; Oxidation-Reduction; Protons

The chemiosmotic hypothesis predicts that buffers which permeate chloroplast membranes should delay the formation of the proton gradient at the onset of illumination. If valinomycin and KCl are present to collapse the electrical potential as well, this delay should result in a lag in initial ATP synthesis. Using rapid-mix, acid-quench techniques, we have found that in light-driven ATP synthesis the permeant buffer imidazole does not increase the initial lag caused by the valinomycin-KCl pair. Similar results are obtained under methyl viologen or phenazine methosulfate/ascorbate-mediated photophosphorylation and are independent of the internal volume of the chloroplasts. Furthermore, we have observed that chloroplasts can synthesize significant amounts of ATP in darkness following an illumination period as short as 100 ms. This capacity for ATP synthesis in darkness after short pre-illumination periods is decreased in the presence of imidazole, and this may account for the apparent lags reported in earlier studies which have used rapid flash photophosphorylation in the presence of permeant buffers. The results of the present study argue that in chloroplasts, initial ATP synthesis and post-illumination ATP synthesis are driven by distinct components of the proton motive potential.

Topics: Adenosine Triphosphate; Ascorbic Acid; Buffers; Chloroplasts; Imidazoles; Kinetics; Light; Methylphenazonium Methosulfate; Paraquat; Photophosphorylation; Plants; Valinomycin