Synthesis and in vitro antimycobacterial activity of N-nicotinoyl-3-(4'- hydroxy-3'-methyl phenyl)-5-[(sub)phenyl]-2-pyrazolines

A series of N-nicotinoyl-3- (4'-hydroxy-3'-methyl phenyl)-5-(substituted phenyl)-2-pyrazolines were synthesized by the reaction between isoniazid (INH) and chalcones and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H37Rv (MTB) and INH-resistant M. tuberculosis (INHR-MTB) using the agar dilution method. Among the synthesized compounds, compound (i) N-nicotinyl-3-(4'-hydroxy-3'-methyl phenyl)-5-(1"- chlorophenyl)-2-pyrazoline was found to be the most active agent against MTB and INHR-MTB, with minimum inhibitory concentration of 0.26 mu m. When compared to INH-compound i was found to be 2.8- and 43.7-fold more active against MTB and INHR-MTB, respectively.