Identification of Elaiophylin Derivatives from the Marine-Derived Actinomycete Streptomyces sp 7-145 Using PCR-Based Screening

A PCR-based genetic screening experiment targeting the dTDP-glucose-4,6-dehydratase gene revealed that a marine sediment-derived strain, Streptomyces sp. 7-145, had the potential to produce glycosidic antibiotics. Chemical investigation of culture extracts of this strain yielded two new 6-deoxyhexose-containing antibiotics, 11',12'-dehydroelaiophylin (1) and 11,11'-O-dimethyl-14'-deethyl-14'-methylelaiophylin (2), together with four known elaiophylin analogues (3-6). Their structures were determined by extensive NMR, MS, and CD analyses. Compounds 1, 3, 4, and 6 showed good antibacterial activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci pathogens.