Phenolic polyketides from the marine alga-derived Streptomyces sp. OUCMDZ-3434.

Five new phenolic polyketides, namely 3- O -methylwailupemycin G ( 1 ), wailupemycin J ( 2 ), R - and S -wailupemycin K ( 3 and 4 ) and wailupemycin L ( 5 ), as well as the known enterocin ( 6 ) and 5-deoxyenterocin ( 7 ) were isolated and identified from the fermentation broth of Streptomyces sp. OUCMDZ-3434 associated with the marine green algae, Enteromorpha prolifera . Their structures including absolute configurations were elucidated according to the spectroscopic analysis, X-ray single crystal diffraction and the Mosher's experiments. Compound 1 showed comparable α -glucosidase inhibition with an IC 50 value of 0.86 mM to acarbose (IC 50 1.12 mM), and compound 4 was cytotoxic on the HeLa cell with an IC 50 value of 8.2 μM. Compounds 2 , 3 and 7 showed anti-H1N1 virus activity with 47.8%, 42.5% and 60.6% inhibitions, respectively at 50 μg/mL (ribavirin, 45.3% inhibition). [ABSTRACT FROM AUTHOR]