Oxygen-bridged cyclooctadienes and other polyketides from the mangrove endophytic fungus Diaporthe sp. ZJHJYZ-1

Nine oxygen-bridged cyclooctadienes (1 - 9), including four undescribed previously (1, 2, 5, and 6), together with a new cyclohexanone derivative (10) and a new oxaspiroundecanone derivative (11), were isolated from the mangrove endophytic fungus Diaporthe sp. ZJHJYZ-1. The structures of compounds were elucidated via detailed NMR, HR-ESI-MS analyses, ECD spectra calculation, 1H - 1H coupling constants comparison and X-ray single-crystal diffraction analysis. In bioassays, compound 8 significantly suppressed six human cancer cell lines, MDA-MB-231, MDA-MB-435, HCT116, A549, SNB19, and PC3, with IC50 values in the range of 1.97 +/- 0.01 - 19.17 +/- 1.02 mu M. And compound 10 promisingly inhibited MDA-MB-231 and PC3 with IC50 values of 2.54 +/- 1.23 and 22.07 +/- 0.64 mu M, respectively.