Antibacterial Activities and Inhibitory Effects of Sitafloxacin (DU-6859a) and Its Optical Isomers against Type II Topoisomerases

The in vitro inhibitory effects of sitafloxacin (DU-6859a) and its three stereoisomers on bacterial DNA gyrase from Escherichia coli, topoisomerase IV from Staphylococcus aureus, and topoisomerase II from human placenta were compared. No correlation was observed between the inhibitory activities of quinolones against bacterial type II topoisomerases and those against human topoisomerase II. Sitafloxacin showed the most potent inhibitory activities against bacterial type II topoisomerases and the lowest activity against human type II topoisomerase.