Design, synthesis and antimicrobial activity of novel quinoline-2-one hybrids as promising DNA gyrase and topoisomerase IV inhibitors

A new series of quinoline-2-one Schiff-base hybrids has been designed and synthesized. Their structure has been established using 1H NMR, 13C NMR, and mass as well as elemental analyses. All compounds were screened for antimicrobial activity and the minimum inhibitory concentration was determined. Compound 6c, one of the most potent compounds achieving (MIC of 0.075, 0.018, 0.018 µg/ml) against B. subtilis, E. coli and S. aureus, respectively, comparable to ciprofloxacin. Moreover, in vitro E. coli topoisomerase IV and DNA gyrase inhibitory activity have been also assigned. 6c showed IC50 of 280± 30 nM, 17.50 ± 1.50 µM against reference Novobiocin with 170 ± 20 nM and 11± 2 µM, respectively.