Polyketides with a 6/6/6/6 Oxaphenalene Pyranone Skeleton from Marine-Derived sp. HDN150000.

Three new structures named naphpyrone I-K (-) that contain a 6/6/6/6 oxaphenalene pyranone skeleton were isolated and purified from a marine-derived sp. HDN155000. Their chemical structures, including configurations, were elucidated by extensive NMR, MS, single-crystal X-ray diffraction, theoretical NMR calculations, DP4+ probability analysis, and ECD analyses. Naphpyrone K () showed cytotoxic activities against L-02, K562, NCI-H446/EP, MDA-MB-231, and NCI-H446 cancer cells with IC values of 5.13, 3.34, 2.50, 2.61, and 2.20 μM, respectively. These findings highlight the potential for screening and developing therapeutic drugs from aromatic polyketides derived from marine actinobacteria.