Three new depsipeptides, fijimycins A-C (1-3), together with the known etamycin A (4), were isolated and identified from the fermentation broth of strain CNS-575, a Streptomyces sp. cultured from a marine sediment sample collected off Nasese, Fiji. The planar structures of the new fijimycins were assigned by combined interpretation of NMR and MS/MS spectroscopic data. These assignments were complicated by the fact that 1-3 occurred as complex amide conformational mixtures. The absolute configurations of the component amino acids were established using the Marfey's method. Fijimycins A-C, and etamycin A, were shown to possess significant in vitro antibacterial activity against three methicillin-resistant Staphylococcus aureus (MRSA) strains with MIC 100 values between 4 and 16 μg mL -1.
Bibliographical noteFunding Information:
This research is a result of financial support from the National Institutes of Health/Fogarty Center International Cooperative Biodiversity Groups program (grant U01-TW007401-01 ) and NIH award RO1 GM084350-01 . We thank the people of Fiji for their hospitality and the government and local resource owners for permission to collect samples in their local offshore waters. We thank C. A. Kauffman for fermentation assistance and S. Kelly for performing the 16S RNA analysis. We also thank A. Mrse (UCSD) for assistance with NMR experiments and Y. Su (UCSD) for HRMS and MS/MS data.
- Antibacterial depsipeptides
- Etamycin class antibacterials
- MRSA activity