The compounds of the formula: ##STR1## wherein R.sup.1 is hydrogen, amino, isonitrile or an organic residue bonded through nitrogen; R.sup.2 is carboxy or a group derivable therefrom; X is hydrogen, methoxy, formylamino, alkyl which may be substituted, alkylthio in which the sulfur atom may be oxidized or azido, or forms a double bond together with the adjacent carbon atom; provided that when R.sup.1 is acetylamino or amino and X is hydrogen, R.sup.2 is not para-nitrobenzyloxycarbonyl or benzhydryloxycarbonyl, or a pharmaceutically acceptable salt thereof, exhibit excellent antimicrobial activity, and are utilized as antimicrobial agents.
化学式为: ##STR1## 其中,R.sup.1 为氢、
氨基、异腈或通过氮原子连接的有机残基;R.sup.2 为羧基或可由其导出的基团;X 为氢、甲氧基、甲酰
氨基、可被取代的烷基、
硫代烷基(其中
硫原子可能被氧化)或偶氮基,或与相邻碳原子形成双键;但当R.sup.1 为乙酰
氨基或
氨基且X为氢时,R.sup.2 不是对
硝基苯甲氧羰基或苯基甲氧羰基,或其药学上可接受的盐。这些化合物表现出优异的抗微
生物活性,并被用作抗微
生物剂。