Mitochondrial oxidative stress and dysfunction induced by isoniazid: study on isolated rat liver and brain mitochondria.

Isoniazid (INH or isonicotinic hydrazide) is used for the treatment and prophylaxis of tuberculosis. Liver and brain are two important target organs in INH toxicity. However, the exact mechanisms behind the INH hepatotoxicity or neurotoxicity have not yet been completely understood. Considering the mitochondria as one of the possible molecular targets for INH toxicity, the aim of this study was to evaluate the mechanisms of INH mitochondrial toxicity on isolated mitochondria. Mitochondria were isolated by differential ultracentrifugation from male Sprague-Dawley rats and incubated with different concentrations of INH (25-2000 µM) for the investigation of mitochondrial parameters. The results indicated that INH could interact with mitochondrial respiratory chain and inhibit its activity. Our results showed an elevation in mitochondrial reactive oxygen species (ROS) formation, lipid peroxidation and mitochondrial membrane potential collapse after exposure of isolated liver mitochondria in INH. However, different results were obtained in brain mitochondria. Noteworthy, significant glutathione oxidation, adenosine triphosphate (ATP) depletion and lipid peroxidation were observed in higher concentration of INH, as compared to liver mitochondria. In conclusion, our results suggest that INH may initiate its toxicity in liver mitochondria through interaction with electron transfer chain, lipid peroxidation, mitochondrial membrane potential decline and cytochrome c expulsion which ultimately lead to cell death signaling.

Synthesis of novel indole hydrazone derivatives and evaluation of their antiplatelet aggregation activity.

Based on the existing reports regarding the antiplatelet aggregation activity of hydrazone derivatives, a series of indole hydrazone derivatives were considered as potential antiplatelet agents and synthesized. The structures of the synthesized compounds were confirmed by spectral data and elemental analysis. The new indole hydrazone derivatives were evaluated for their ability to inhibit platelet aggregation induced by adenosine diphosphate (ADP) and arachidonic acid (AA). Compounds 1h and 3h exhibited remarkable activity against arachidonic acid induced platelet aggregation with IC(50) values comparable to that of indomethacin and compound 1i efficiently inhibited platelet aggregation induced by both ADP and AA.

One pot synthesis and biological activity evaluation of novel Schiff bases derived from 2-hydrazinyl-1,3,4-thiadiazole.

Considering the structural features of a group of known potent inhibitors of human platelet aggregation containing hydrazone structural backbone, a series of novel hydrazone derivatives of 2-hydrazinyl-1,3,4-thiadiazole were synthesized using a one-pot process and tested for their inhibitory activity against platelet aggregation induced by arachidonic acid and ADP. Among the derivatives, compounds 3l, 3o and 3p exhibited the highest antiplatelet aggregation activity. The derivatives were also screened for their potential antimycobacterial activity and compounds 3g, 3k, 3p and 3q were among the most active compounds.

Synthesis, antimycobacterial and anticancer activity of novel indole-based thiosemicarbazones.

Based on the structural elements of bioactive indole-based compounds, a series of novel 1-substituted indole-3-carboxaldehyde thiosemicarbazones were synthesized as potential antimycobacterial and anticancer agents. The derivatives were prepared via a two-step methodology including N-alkylation(benzylation) of indole-3-carboxaldehyde and conversion of the intermediate aldehydes to corresponding thiosemicarbazones. The derivatives were evaluated for their antimycobacterial activity and compounds 3d (R = propyl) and 3q (R = 4-nitrobenzyl) were among the most potent and selective derivatives with IC50 values of 0.9 and 1.9 µg/mL respectively. The anticancer activity of the derivatives was also assessed against a panel of tumor cell lines. Compounds 3t, 3u, 3v and 3w efficiently inhibited the majority of the cancer cell lines with considerable selectivity.

Synthesis and Antibacterial Activity of Novel Hydroxy Semicarbazone Derivatives.

A series of hydroxyl semicarbazone derivatives of substituted diaryl ketones and acetophenones were synthesized and their structures were confirmed by analytical and spectroscopic methods including elemental analysis, infrared and nuclear magnetic resonance spectroscopy. The derivatives were prepared by a condensation reaction between N-hydroxy semicarbazide and substituted diaryl ketones or acetophenones leading to the desired hydroxysemicarbazones with excellent purity. The synthesized hydrazones were then evaluated for their inhibitory activity against bacterial strains including S. aureus, E. Coli, P. aeruginosa, K. pneumonia and M. luteus. Among the tested derivatives, compounds 2, 6 and 7 exhibited the highest bioactivity. Analysis of the activity data suggests that hydrophilicity is an important factor for the bioactivity of compounds 2 and 6 and also their selectivity over the gram-negative bacteria.

Synthesis, Antiplatelet Activity and Cytotoxicity Assessment of Indole-Based Hydrazone Derivatives.

A series of indole-based aryl(aroyl)hydrazone analogs of antiplatelet indole-3-carboxaldehyde phenylhydrazone were synthesized by the Schiff base formation reaction and their antiplatelet activity was assessed using human platelet rich plasma. The platelet concentrate was obtained using a two-step centrifugation protocol and ADP, arachidonic acid and collagen were used as inducers of platelet aggregation. Based on the results, substituted phenylhydrazones showed promising activity. Among them, compound 1i was the most potent derivative with an IC50 comparable to that of indomethacin as a standard drug. The hydrazone derivatives were also tested for their cytotoxicity using on platelet concentrates and fibroblast L929 cells. The majority of the derivatives showed an acceptable selectivity towards antiplatelet aggregation activity. Based on the activity data, phenylhydrazone derivatives (1a-i) exhibited considerable antiplatelet activity and minimal toxic effect on platelet cells. The results of the present study could provide a better understanding of the structure activity relationship of antiplatelet indolehydrazones.

Synthesis of thioether derivatives of quinazoline-4-one-2-thione and evaluation of their antiplatelet aggregation activity.

A series of 2-(arylmethylthio)-3-phenylquinazolin-4-one derivatives have been synthesized and their antiplatelet aggregation activities were assessed against ADP and arachidonic acid-induced platelet aggregation in human plasma. Among the tested thioethers, derivative 2, 3, 5 and 16 were the most potent compounds with satisfactory IC50 for inhibition of platelet aggregation induced by ADP. Analysis of global physicochemical parameters shows some correlations between activities and molecular volume and also surface area of the studied derivatives.

Synthesis and Antimycobacterial Activity of Symmetric Thiocarbohydrazone Derivatives against Mycobacterium bovis BCG.

In this work, we reported the synthesis and evaluation of antimycobacterial and antifungal activity of a series of thiocarbohydrazone derivatives which are thiacetazone congeners. The target compounds were synthesized in superior yields by reacting thiocarbohydrazide with different aromatic aldehydes and methyl ketones. Compounds 8, 19 and 25 were found to be the most potent derivatives, exhibiting acceptable activity against Mycobacterium bovis BCG compared to thiacetazone and ethambutol as reference substances. Compounds 8, 15 and 25 exhibited the highest activity against Candida albicans. The most active compounds had a completely different aromatic ring system with various electronic, steric and lipophilic natures. This is understandable in light of the fact that carbohydrazone derivatives must undergo a metabolic activation step before exerting their anti-TB activity and different SAR rules govern each one of these two processes.