Study of anti-MRSA bioactive constituents from a marine actinomycetes Micromonospora sp.(No.69)

Objective To study the anti-MRSA bioactive constituents of a marine actinomycete Micromo nospora sp.(No.69).Methods By bioassay-guided separation,the compounds were isolated and purified from the methanol extract of Micromonospora sp.(No.69) by various column chromatographies. Their structures were identified by chemical and spectral analyses.Results Eight compounds were obtained and identified as cyclo-(L-Val-L-Pro)(1),cyclo-(L-Ile-L-Pro)(2),cyclo-(L-Leu-L-Pro)(3), cyclo-(Gly-L-Pro)(4),cyclo-(Thr-L-Pro)(5),cyclo-(L-Ala-L-Pro)(6),cyclo-(L-Tyr-L-Pro)(7), cyclo-(L-Phe-L-Pro)(8),respectively.Compounds 1 and 2 showed active against MRSA with IC_(50) values of 3.2 and 6.5 mmol·L~(-1).Conclusion:Compounds 1～8 were obtained from the genus of Micromonospora sp.for the first time,and compounds 1 and 2 showed activity against MRSA.