M. Iqbal Choudhary

Synthesis, antioxidant activities and urease inhibition of some new 1,2,4-triazole and 1,3,4-thiadiazole derivatives

New series of 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones (8a-j) and 2,5-disubstituted-1,3,4-thiadiazoles (9a-h) were synthesized by dehydrative cyclization of hydrazinecarbothioamide derivatives (7a-k) by refluxing in 4N aqueous sodium hydroxide and by overnight stirring with polyphosphoric acid, respectively. The structures of the newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectroscopic studies and the synthesized compounds were screened for their antioxidant and urease inhibition activities. N-(2,4-Dimethylphenyl)-5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine (9h) showed excellent antioxidant activity more than the standard drug whereas 4-(2,4-dimethylphenyl)-5-(3-nitrophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8d) and 4-(2,3-dimethylphenyl)-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (8e) exhibited potent urease inhibitory activities.

Bioactive natural products as a potential source of new pharmacophores. A theory of memory

The plant kingdom offers a rich source of structural biodiversity in the form of a variety of natural products. Our work on new bioactive compounds from medicinal plants has led to the isolation and structure elucidation of a number of exciting new pharmacophores. Bioassay-guided fractionation has recently led to the discovery of a series of new acetylcholinesterase, urease and a-glucosidase inhibitors, antioxidants and other classes of bioactive compounds, which will be presented. A theory based on hydrogen bonding on the chemical basis of memory storage in the brain is presented.

N-Alkylation of anilines, carboxamides and several nitrogen heterocycles using CsF–Celite/alkyl halides/CH3CN combination

It has been found that the N-alkylation of aniline, carboxamides and heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen can be accomplished with alkyl halides in acetonitrile and cesium fluoride–celite employed as a solid base. In this manner, pyrrole, indole, pyrazole, imidazole, benzimidazole, carbazole, phthalimide, indazole, indoline, 2-pyrrolidinone, piperidine and 1,2,4-triazole can be successfully alkylated. The procedure is convenient, efficient and generally gives rise to the N-alkylated product exclusively.

Synthesis of bis-Schiff bases of isatins and their antiglycation activity

Bis-Schiff bases 1-27 have been synthesized and their in vitro antiglycation potential has been evaluated. Compounds 21 (IC(50)=243.95+/-4.59microM), 20 (IC(50)=257.61+/-5.63microM), and 7 (IC(50)=291.14+/-2.53microM) showed an excellent antiglycation activity better than the standard (rutin, IC(50)=294.46+/-1.50microM). This study has identified a series of potential molecules as antiglycation agents. A structure-activity relationship has been studied, and all the compounds were characterized by spectroscopic techniques.

Antifungal steroidal lactones from Withania coagulance

Two new withanolides, 14,15 beta-epoxywithanolide I [(20S,22R) 17 beta, 20 beta-dihydroxy-14 beta,15 beta-epoxy-1-oxo-witha-3,5,24-trienolide] and 17 beta-hydroxywithanolide K (20S,22R) 14 alpha,17 beta,20 beta-trihydroxy-1-oxo-witha-2,5,24-trienolide] have been isolated from the whole plant of Withania coagulance and their structures were elucidated by spectroscopic techniques. The latter compound was found to be active against a number of potentially pathogenic fungi.

Schiff bases of 3-formylchromone as thymidine phosphorylase inhibitors.

3-Formylchromone (1), 3-methyl-7-hydroxychromone (2) and Schiff bases of 3-formylchromone 3-19 have been synthesized and their anti-thymidine phosphorylase inhibitory activity was evaluated. Compounds 1-19 showed a varying degree of thymidine phosphorylase inhibition with IC(50) values 19.77+/-3.25 to 480.21+/-2.34 microM. Their activity was compared with the standard 7-deazaxanthine (IC(50)=39.28+/-0.76 microM). Compound 12 showed an excellent thymidine phosphorylase inhibitory activity with an IC(50) value of 19.77+/-3.25 microM, better than the standard. Compound 4 also showed an excellent inhibitory activity (IC(50)=40.29+/-4.56 microM). The parent 3-formylchromone (1) and 3-methyl-7-hydroxychromone (2) were found to be inactive. The structures of the compounds were elucidated by using spectroscopic techniques, including (1)H NMR, EI MS, IR, UV and elemental analysis.

Synthesis and In Vitro Leishmanicidal Activity of Some Hydrazides and Their Analogues

Twenty-one hydrazides were synthesized by treating different esters with hydrazine hydrate. Substituted hydrazides were obtained by treating hydrazides with alkyl/aryl/acyl halides. Some of these compounds exhibit potential in vitro leishmanicidal activity. The structures of all the synthesized compounds were confirmed by spectroscopic analysis.

Synthesis of novel inhibitors of β-glucuronidase based on benzothiazole skeleton and study of their binding affinity by molecular docking.

Benzothiazole derivatives 1-26 have been synthesized and their in vitro β-glucuronidase potential has been evaluated. Compounds 4 (IC(50)=8.9 ± 0.25 μM), 5 (IC(50)=36.1 ± 1.80 μM), 8 (IC(50)=8.9 ± 0.38 μM), 13 (IC(50)=19.4 ± 1.00 μM), 16 (IC(50)=4.23 ± 0.054 μM), and 18 (IC(50)=2.26 ± 0.06 μM) showed β-glucuronidase activity potent than the standard (d-saccharic acid 1,4-lactone, IC(50)=48.4 ± 1.25 μM). Compound 9 (IC(50)=94.0 ± 4.16 μM) is found to be the least active among the series. All active analogs were also evaluated for cytotoxicity and none of the compounds showed any cytotoxic effect. Furthermore, molecular docking studies were performed using the gold 3.0 program to investigate the binding mode of benzothiazole derivatives. This study identifies a novel class of β-glucuronidase inhibitors.

Protocols on safety, efficacy, standardization, and documentation of herbal medicine (IUPAC Technical Report)

This Technical Report compiles and analyzes the current scientific knowledge on herbal medicine and highlights the practical ways for ensuring the safety of herbal preparations and evaluating their claimed efficacy. Emphasis has been given to the methods for standardization of herbal medicine and the ways and means for moving forward to achieve the difficult goal of preparing herbal medicines of consistent quality and effects. Pragmatic approaches have been recommended to overcome the difficulties in (i) protecting intellectual property rights (IPR); (ii) producing safe, potent, standardized, and affordable herbal medicine; and (iii) documenting the knowledge base on herbal medicine in an easily accessible format.

3-Formylchromones: Potential antiinflammatory agents

The synthesis and characterization of 3-formylchromone (1) and its derivatives 2-24 and evaluation of their potential antiinflammatory activities is reported here. These compounds were characterized by (1)H NMR, EI MS, IR, and UV spectroscopic techniques and elemental analysis. The synthesized compounds were evaluated by using various in vitro and in vivo assay models for antiinflammatory activity and their effects were compared with known standard drug such as aspirin and indomethacin. Among all tested compounds, 1, 2, 5, 6, 9, 14, 16-19, 21-23, showed promising antiinflammatory activities. The results and SAR has been discussed in this report.