In recent years, bacteria resistant to penicillin, cephalosporin, and the like have emerged, and infection with multiresistant and methicillin-resistant Staphylococcus aureus (MRSA) causes severe problems in clinical fields. As typical drugs for treating and preventing MRSA, there are used vancomycin, teicoplanin, arbekacin, linezolid, and the like. In particular, a glycopeptide antibiotic such as vancomycin is generally used as for treatment of MRSA an antibacterial agent because there are few bacteria resistant to the antibiotic. However, vancomycin intermediate-resistant Staphylococcus aureus (VISA) has been discovered in 1996, and emergence of vancomycin-resistant enterococci (VRE) and vancomycin-resistant Staphylococcus aureus (VRSA) has been reported heretofore. Therefore, the agent needs to be used with great care. Accordingly, development of a novel compound having sufficient effects on drug-resistant bacteria as well has been desired.
Many studies have been made on antibacterial agents for MRSA. A certain kind of flavanone derivative extracted from a bay tree has been reported to show an antibacterial activity against MRSA (Non Patent Literature 1). In addition, comparison of antibacterial activities of phytochemical flavanone derivatives against MRSA has been reported (Non Patent Literature 2). However, there is no report about an effect on a microorganism having stronger resistance such as VRSA, and development of a more effective novel compound has been desired.