Synthesis and evaluation of antibacterial and antimycobacterial activities of some new pyrazole derivatives

Pyrazoles and sulfonamides are ubiquitously classified as structural fragments in antimicrobial and antimycobacterial agents. In this present study, a series of 14 pyrazole based sulfonamide derivatives (7-20) were designed, synthesized regioisomeric structures were elucidated by spectroscopic methods. All target compounds were evaluated for their in vitro antibacterial potential against selected Gram (+) and Gram (-) bacterial strains as well as for their antimycobacterial activity. The bioactivity results demonstrated that all compounds showed selective antibacterial activity against B. subtilis with MIC values of 1-125 mu g/mL. Especially, 1-[(2,4-dichlorophenyl)methyl]-N-(4- methoxybenzenesulfonyl)-3-methyl-1H-pyrazole-5-carboxamide (9), 14(2,4-Dichlorophenyl)methyll-N-(4- fluorobenzenesulfonyl)-3-methyl-1H-pyrazole-5-carboxamide (10), N-(3,5-Dichlorobenzenesulfonyl)-1-[(2,4- dichlorophenyl)methyl]-3-methyl-1H-pyrazole-5-carboxamide (11) and 1-[(2,4-dichlorophenyl)methyl]-N-(4-fluorobenzenesulfonyl)-5-methyl-1H-pyrazole-3-carboxamide (17) displayed the highest antibacterial activity against B. subtilis with MIC values of 1 mu g/mL, which were more effective compared to the reference chloramphenicol. As a conclusion, the snythesized new pyrazole sulfonamides stand out as promising antimicrobial agents for further development.