Synthesis and biological evaluation of some novel 1,4-dihydropyridines as potential antitubercular agents

Recent studies showed that 1,4-dihydropyridine-3,5-dicarbamoyl derivatives with lipophilic groups have significant antitubercular activity. In this study, we have synthesized new derivatives of 1,4-dihydropyridines bearing carbmethoxy and carbethoxy group at C-3 and C-5 of the 1,4-dihydropyridine ring. In addition, 1H-pyrazole ring is substituted at C-4 position. These analogues were synthesized by multi-component Hantzsch reaction. The in vitro antitubercular activity of compounds against Mycobacterium tuberculosis H(37) Rv was evaluated. The lowest minimum inhibitory concentration value, 0.02 μg/mL and SI > 500, was found for dimethyl 1,4-dihydro-4-(3-(4-nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)-2,6-dimethylpyridine-3,5-dicarboxylate 3f, diethyl 1,4-dihydro-4-(3-(4-fluorophenyl)-1-phenyl-1H-pyrazol-4-yl)-2,6-dimethylpyridine-3,5-dicarboxylate 4c and diethyl 1,4-dihydro-4-(3-(4-bromophenyl)-1-phenyl-1H-pyrazol-4-yl)-2,6-dimethyl pyridine-3,5-dicarboxylate 4e, making them more potent than first-line antitubercular drug isoniazid. In addition, these compounds exhibited relatively low cytotoxicity.