| abstract |
A novel pyridonecarboxylic acid derivative or salt thereof is provided having an excellent effect on bacteria such as methicillin resistant staphylococcus aureus, pseudomonas aeruginosa and clostridium difficile and not susceptible to drug efflux pumps, and an antimicrobial agent comprising the same. a pyridonecarboxylic acid derivative represented by formula (1), wherein r1 is a hydrogen atom, a halogen atom, a lower alkyl group or an amino group; R2 is a group -nh-r6, wherein r6 is a hydrogen atom, a lower alkyl group, a lower alkylamino group or the like; a -o-r7 group, where r7 is a hydrogen atom, a lower alkyl group or the like; a group - (ch2) m-r8, where r8 is an amino group or the like and m is an integer from 1 to 4); or a cyclic amino group represented by the following formula (2), wherein y represents nh or c-r9ar9b, wherein r9a and r9b are independently hydrogen atom, a lower alkyl group, an amino group, a lower alkyl amino group or the like. ; and n and p are an integer of 1 or 2; R3 is a hydrogen atom, a halogen atom, a lower alkyl group or the like; R4 is a hydrogen atom or a carboxyl-protecting group; and R5 is a hydrogen atom or a hydroxyl-protecting group; or a salt of it. |