Study On The Secondary Metabolites Of Two Strains Of Marine Rare Ctinomycetes

Aim To study the MRSA inhibitory bioactive constituents of a marine Actinomycetes Micromonospora sp. (No.69) and the Caspase 3 inhibitory bioactive constituents of a marine Actinomycetes Microbispora sp. (X212030) by bioassay-guided isolation. Methods Various chromatographic and spectroscopic methods were applied for the isolation and structure identification of the compounds. Results Nine compounds were obtained from the methanol extract of Micromonospora sp. (No.69), which were 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), andβ-sitosterol (9), respectively. Thirteen compounds were obtained from the methanol extract of Microbispora sp. (X212030), and among which the chemical structures of seven ones were identified. Among the severn compounds obtained from the methanol extract of Microbispora sp. (X212030), four compounds were identified as 2,3,7, and 8, the other three compounds were identified as 3-hydroxyacetyl-indole(10), cyclo-(D-Tyr-L-Pro) (11), cyclo-(D-Phe-L-Pro) (12), respectively. Conclusion Compunds 1-8 were obtained from the genus of Micromonospora for the first time, and compounds 1,2 and 9 showed weak inhibitory activities against MRSA with IC50 values of 3.2,6.5 and 2.8μmol/ml, respectively. Compunds 2,3,7,8 and 10-12 were obtained from the genus of Microbispora for the first time.