Synthesis and Biological Evaluation of Pyrazole-Based Schiff Bases as Antibacterial and Antifungal Agents

Pyrazole and its derivatives are fascinating heterocyclic compounds because of their significant biomedical applications, including anticancer, antimalarial, antimicrobial, antifungal, and antitubercular properties. Pyrazole ring is a recognized structure found in many pharmacologically active substances. In this study, the synthesis of (E)-4-(benzylideneamino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one deriva­tives 7a–7j was accomplished through a multistep procedure. The process involves the condensation and cyclization of 1-methyl-2-phenylhydrazine with ethyl 3-oxobutanoate, followed by nitration, reduction, and subsequent reaction with substituted benzaldehydes. The synthesis was optimized by exploring the effects of the solvent ratio and reaction time on the yield of 7a. The synthesized compounds were characterized based on their spectral data (IR, 1H and 13C NMR, and mass spectra). The antimicrobial activities of all synthesized compounds were evaluated against four bacterial strains (S. aureus MTCC 2408, B. cereus MTCC 430, E. coli MTCC 2412, and P. aeruginosa MTCC 2081) and two fungal strains (C. albicans MTCC 227, and C. tropicalis MTCC 230).