Synthesis and antimicrobial activity of 3-(4'-hydroxy-3'-methylphenyl)-5-[(substuted) phenyl]-4,5-dihydro-1H-1-pyrazolyl-4-pyridylmethanone derivatives.

A series of 3-(4'-hydroxy-3'-methylphenyl)-5-[(substituted) phenyl]-4,5-dihydro-1H-1-pyrazolyl-4-pyridylmethanone derivatives were synthesized by the reaction between isoniazid (INH) and various chalcones and were tested for their antimicrobial activity in vitro against Staphylococcus aureus 209p, Escherichia coli ESS 2231, Aspergillus fumigatus, Candida albicans, Candida albicans ATCC 10231, Candida krusei GO3 and Candida glabrata HO5. Among the synthesized compounds, all the compounds possess the significant antibacterial activity. Compounds I(III) and I(x), i.e. 3-(4'-hydroxy-3'-methylphenyl)-5-(4"-dimethylaminophenyl)-4,5-dihydro-1H-1-pyrazolyl-4-pyridyl methanone and 3-(4'-hydroxy-3'-methylphenyl)-5-(2",6"-dichlorophenyl)-4,5-dihydro-1H-1-pyrazolyl-4-pyridylmethanone were found to be the most active agents against used bacterial and fungal strains with minimum inhibitory concentration of less than 0.5 microg/mL and were equally active as standard drugs Ofloxacin and Fluconazole.