| abstract |
A compound represented by formula (I):n wherein R¹ represents a hydrogen atom or a methyl group; R² and R³, which may be the same or different, each represents a hydrogen atom or a lower alkyl group; and R⁴ represents a carboxyl group, a lower alkoxycarbonyl group, a carbamoyl group, a lower alkylcarbamoyl group, a di-lower alkylcarbamoyl group, or a carbonyl group substituted with a heterocyclic group selected from the group consisting of an aziridinyl group, an azetidinyl group, a pyrrolidinyl group, a piperidino group, a morpholino group, a thio-morpholino group, a piperazinyl group, and a 4-lower alkyl-1-piperazinyl group, nor a pharmaceutically acceptable salt or ester thereof. The compound of formula (I) and their salts or esters exhibit excellent antibacterial activity. |