Antibacterials and Antimycotics: Part 1: Synthesis and Activity of 2-pyrazoline Derivatives

A series of 3-styryl-1,5-diphenyl and 5-styryl-1,3-diphenyl 2-pyrazolines of different substitutions has been synthesized by condensation of substituted alpha,beta-unsaturated ketones with phenylhydrazine hydrochloride in presence of catalytic amount of concentrated HCl. Compounds in the 3-styryl series had OMe, NMe2, NO2, OH and isopropyl substituents and those in the 5-styryl series had OMe, NMe2 and NOs. The 3-styryl-1,5-diphenyl compounds showed little variation in antibacterial activity towards gram-positive and gram-negative bacteria in terms of geometric mean minimum inhibitory concentrations (MIC). The 4',4"-NMe2, 4',4"-NO2 and 4',4"-OMe compounds were found to possess the highest activity in the series. The 5-styryl-1,3-diphenyl series showed lower activities than the 3-styryl series. The in vitro antimycotic activity of the 4',4"-OH and 2',2"-OH substituted compounds showed good activity than the other molecules in the two series.