Cyclodipeptides Isolated from a Marine-Derived Fungus Penicillium chrysogenum M612 of Bai Tu Long Sea, Quang Ninh, Vietnam

Bacterial resistance is getting more and more serious, and Vietnam is one of the high bacterial resistance prevalent countries in the world. Hence, the development of new antimicrobial agents, domestically, is urgently needed. During the course of our screening program, the ethyl acetate extract of a marine-derived fungus strain (Penicillium chrysogenum M612), isolated from sediment collected in Bai Tu Long sea, showed good inhibition activities against tested clinical important microbial pathogens. Subsequent analysis of the extracts prepared from the strain M612’s culture broth (50L) led to the isolation of seven cyclodipeptides. Structure of isolated compounds was determined, based on MS; NMR spectroscopic data analysis and compared with literature, as cyclo-(L-Pro-L-Leu) (1), cyclo-(L-Pro-L-Val) (2), cyclo-(L-Ala-L-Pro) (3), cyclo-(L-Pro-L-ILe) (4), cyclo-(L-Pro-L-Phe) (5), cyclo-(D-Pro-D-Phe) (6) and cyclo-(L-Pro-L-Tyr) (7). All the compounds were previously reported to have antimicrobial activities. The obtained results suggested that strain M612 can be further studied to develop an antimicrobial agent.