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 a-glucosidase inhibition with an IC50 value of 0.86 mM to acarbose (IC50 1.12 mM), and compound 4 was cytotoxic on the HeLa cell with an IC50 value of 8.2 mu M. Compounds 2, 3 and 7 showed anti-H1N1 virus activity with 47.8%, 42.5% and 60.6% inhibitions, respectively at 50 mu g/mL (ribavirin, 45.3% inhibition). (C) 2017 Elsevier Ltd. All rights reserved.