Three New Depsipeptides, Homiamides A-C, Isolated from Streptomyces sp., ROA-065

Three new depsipeptides, homiamides A-C (1-3), were isolated from a marine sediment-derived strain of Streptomyces sp., ROA-065. The planar structures of homiamides A-C (1-3) were elucidated using mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopic data. The absolute configurations of 1-3 were deduced from the application of the Marfey's method and GC-MS analysis after formation of the O-trifluoroacetylated (S)-(+)-methyl-2-butyl ester derivatives of amino acids. Compounds 1-3 exhibited weak anti-bacterial activities against both Gram-positive bacteria and Gram-negative bacteria, with compound 1 showing MIC values of 32-64 μg/mL. In antifouling assays, compounds 1 and 2 displayed moderate activity against Micrococcus luteus KCTC 3063, while compound 3 exhibited weak activity against all tested bacteria.