Discovery of a New DNA Gyrase A Inhibitor, 4-(1-methyl-6-nitroquinolin-1-ium-4-yl)amino-N-4-(1-methylpyridin-1-ium-4-yl)aminophenylbenzamide

ABSTRACT

Escherichia coli (E. coli) is a clinically important causative organism that can lead to urinary tract infections. Quinolone antibiotics are among the first-line treatments for urinary tract infections. However, the frequency of resistance to quinolone in E. coli has been increasing. Therefore, new antimicrobial agents that can be used for treatment in lieu of quinolone antibiotics are needed. In this study, thirty-six compounds with higher scores in a virtual screening based on the three-dimensional structure of E. coli DNA gyrase were selected for in vitro antimicrobial activity testing. An in vitro test confirmed the antimicrobial activity of 4-[(1-methyl-6-nitroquinolin-1-ium-4-yl)amino]-N-[4-[(1-methylpyridin-1-ium-4-yl)amino]phenyl]benzamide (ZINC18057104) against E. coli among the 36 compounds. The minimum inhibitory concentration (MIC) of ZINC18057104 against E. coli ATCC® 25922™ was 2 μg/ml, and the MIC₅₀ and MIC₉₀ for the 72 quinolone-resistant E. coli clinical isolates were 4 and 64 μg/ml, respectively. ZINC18057104, which has a quinoline structure which is similar to the quinolone antibiotics, is predicted to exhibit antimicrobial activity in quinolone-resistant E. coli because it has different molecular interactions with the DNA gyrase than that of existing quinolone antibiotics.