ascorbic-acid and 1-4-dihydropyridine

New 5-aryl-10-(4-(4-methoxyphenyl)thiazole-2-yl)-9,10-dihydropyrido[2,3-d:5,6-d']dipyrimidinone-2,4,6,8-(1H,3H,5H,7H)-tetraones 6a-d were synthesized through one-pot four-component reaction of aldehydes, barbituric acid, and thiazole using Zn(2+) @KSF under reflux condition. The key features of this reaction are: incorporating four heterocyclic rings, using a heterogeneous and efficient catalyst, high yield, and easy-to-setup reaction. The structure of the products was confirmed by FT-IR, (1)H NMR, and (13)C NMR spectra. The antibacterial activities of compounds 6a-d were screened against Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa, and Staphylococcus aureus bacterial strains using the zone inhibition method. Also, the 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of compounds 6a-d were evaluated. All compounds showed good antioxidant capacity in comparison to ascorbic acid. The IC50 values of the antioxidant activity were calculated. The proposed mechanism for antioxidant activity is discussed.

Topics: Anti-Bacterial Agents; Antioxidants; Ascorbic Acid; Bacteria; Biphenyl Compounds; Carbon-13 Magnetic Resonance Spectroscopy; Catalysis; Dihydropyridines; Disk Diffusion Antimicrobial Tests; Drug Design; Green Chemistry Technology; Molecular Structure; Picrates; Proton Magnetic Resonance Spectroscopy; Spectroscopy, Fourier Transform Infrared; Structure-Activity Relationship; Zinc

Naproxen is one of the most potent NSAIDs and plays an important role in the treatment of neurodegenerative diseases. Poor brain delivery of naproxen at therapeutic doses, in addition to its serious gastrointestinal side effects, has prompted research into the development of a specific carrier system that is capable of delivering naproxen to the brain at smaller doses. The purpose of this study was to evaluate two brain-specific carrier systems of naproxen. The first was the dihydropyridine/pyridinium redox system that utilized a lipophilic chemical delivery system coupled to the carboxylic acid group of naproxen through an ethanolamine linker. Secondly, an ascorbic acid system, which has reducing properties and acts as a biological carrier through sodium-dependent vitamin-C transporter, was used for brain-specific delivery of naproxen. The prepared prodrugs were stable in aqueous buffers (pH 1.2 and 7.4) and rapidly hydrolyzed in biological fluids. Bioavailability studies revealed that both prodrugs 10 and 17 were rapidly cleared from blood with half lives of about 1 h, which will likely decrease systemic adverse effects. The rapid clearance from the blood was accompanied by an increase in the prodrug concentration in the brain, which occurred as a result of the prodrug being more locked in compared to the parent drug naproxen.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Ascorbic Acid; Body Fluids; Brain; Cyclooxygenase Inhibitors; Dihydropyridines; Drug Carriers; Humans; Hydrolysis; Naproxen; Prodrugs; Solutions

A group of 26 2,6-dimethyl-3,5-disubstituted and 2,6-dimethyl-3,4, 5-trisubstituted-1,4-dihydropyridines (1,4-H(2)Py=1,4-DHPs) and five related pyridines were studied as inhibitors of rat liver mitochondrial swelling and O(2) uptake by ascorbic acid-dependent lipid peroxidation (LP) and as modulators of mitochondrial swelling induced by Na(+)-linoleate or Na(+)-pyrophosphate. 1,4-DHPs studied include 4-unsubstituted and 4-methyl- and 4-phenyl-substituted 3, 5-dialkoxycarbonylderivatives of 2,6-dimethyl-1,4-DHP with variations in alkoxy chain length and composition, 4-unsubstituted and 4-methyl-, 4-aryl- and 4-pyridyl-substituted 3, 5-dianilidocarbonylderivatives, and a structurally related group of 3,5-dipyridylamidocarbonylderivatives. Many 1,4-DHPs possess marked antioxidant (AO) and membrane stabilizing activity, expressed as the mitochondrial swelling (deltaA(520)/t) and/or O(2) uptake rate decrease (V(0)/V) as well as prolongation of the induction period (tau/tau(0)) of mitochondrial swelling and/or O(2) uptake at ascorbic acid-dependent LP of rat liver mitochondria. 4-Unsubstituted 3,5-dialkoxycarbonyl-2,6-dimethyl-1,4-DHPs, as well as 4-unsubstituted or those possessing lipophylic 4-aryl- groups 3, 5-diamido-2,6-dimethyl-1,4-DHPs, reveal marked AO and membrane stabilizing properties. Oxidized (heteroaromatized) derivatives have minimal activity. Perhaps 1,4-DHPs preferably act as antioxidants on stages of initiation and prolongation of LP chain reactions at low concentrations: IC(50) (when V(0)/V or tau/tau(0)=2) are 0.1 microM to 100 microM. At 100 microM 3,5-di-p-hydroxyphenoxycarbonyl- and 3, 5-di-p-tolyloxycarbonyl-2,6-dimethyl-1,4-DHPs, as well as 3, 5-diethoxycarbonyl-2,6-dimethylpyridine (oxidized form of Hantzsch ester) and 3,5-diamyloxycarbonyl-2,6-dimethylpyridine, alter the mitochondrial swelling rate in the presence of natural protonophore Na(+)-linoleate (0.063 mM and 0.125 mM). 3,5-Di-n-butyloxycarbonyl-2, 6-dimethyl-1,4-DHP at 100 microM completely stops mitochondrial swelling in the presence of 0.8 mM Na(+)-pyrophosphate. In the presence of many of the 1,4-DHPs, the lipid peroxidation process was inhibited. However, the swelling process could be prolonged, promoted, accelerated or inhibited-depending on 1,4-DHPs structure, concentration, the type of initiators of the swelling process and the medium composition.

Topics: Animals; Antioxidants; Ascorbic Acid; Calcium Channel Blockers; Dihydropyridines; Diphosphates; Linoleic Acid; Lipid Peroxidation; Male; Mitochondrial Swelling; Molecular Structure; Rats; Rats, Wistar

1. Lipid peroxidation in rat brain slices was induced by Fe+3/ascorbate. 2. Brain lipid peroxidation, as measured by malondialdehyde formation, was inhibited by all the tested nitro aryl 1,4-dihydropyridine derivatives over a wide range of concentrations. The time-course antioxidant effects of the most representative agents were assessed. On the basis of both time-course and IC50 experiments the tentative order of antioxidant activity on rat brain slices could be: nicardipine>nisoldipine> (R,S/S,R)-furnidipine > (R,R/S,S)-furnidipine>nitrendipine>nimodipine> nifedipine. 3. 1,4-Dihydropyridine derivatives that lack of a nitro group in the molecule (isradipine, amlodipine) also inhibited lipid peroxidation in rat brain slices but at higher concentrations than that of nitro-substituted derivatives. 4. All the tested nitroso aryl derivatives [2,6-dimethyl-4-(2-nitrosophenyl)-3,5-pyridinedicar. boxylic acid dimethyl ester (NTP), nitrosotoluene, nitrosobenzene] were more potent inhibitors of lipid peroxidation than were the parent nitro compounds. In conclusion, on the basis of the IC50 values determined, the rank order of antioxidant potency for these derivatives can be established as: ortho-nitrosotoluene>NTP>nitrosobenzene.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Calcium Channel Blockers; Dihydropyridines; Ferric Compounds; In Vitro Techniques; Lipid Peroxidation; Nisoldipine; Nitroso Compounds; Oxygen; Rats; Rats, Wistar; Time Factors