Novel 2-(benzo[d]thiazol-2-yl)-1-(3-methyl-5-substituted-phenyl-4,5-dihydropyrazol-1-yl)ethanone Derivatives: Synthesis and Antibacterial Activity

A series of novel 2-(benzo[d]thiazol-2-yl)-1-(3-methyl-5-substituted-phenyl-4,5-dihydropyrazol-1-yl)ethanone derivatives were synthesized and characterized by NMR, ESI-MS. Biological activity tests results show that compounds 4a, 4b, 4d and 4g displayed activity with MIC of 1.562 μg/mL against B. subtilis ATCC 6633, compound 4d displayed significant activity with MIC of 1.562 μg/mL against S. aureus ATCC 6538. Compound 4a with potent antibacterial activities strongly inhibited S. aureus DNA gyrase and B. subtilis DNA gyrase with IC50s of 0.5 μg/ml against S. aureus DNA gyrase and B. subtilis DNA gyrase.