Synthesis and Antimicrobial Activity of New 4-Methyl-2-(3-pyridyl)thiazolyl Chalcones and Pyrazolines

In an attempt to develop active antimicrobial agents, a set of new thiazolyl chalcones has been synthesized by the Claisen-Schmidt reaction of 5-acetyl-4-methyl-2-(3-pyridyl)thiazole with various heterocyclic aldehydes in alkali media. Reaction of chalcones with hydrazine hydrate has resulted in pyrazolines that have been assessed for in vitro antimicrobial activity against ten bacterial and five fungal human pathogenic strains using the disk diffusion assay. The synthesized pyrazolines demonstrate antimicrobial activity higher than that of synthesized chalcones. 2-Thienylchalcone has been determined as the most active against P. aeruginosa. Three pyrazolines are characterized by distinctive activity towards Gram-negative bacteria S. flexneri and P. aeruginosa. Two pyrazolines demonstrate equipotent antifungal activity with amphotricin B against A. clavatus.