Two new diterpenoids from the endophytic fungus Trichoderma sp.Xy24 isolated from mangrove plant Xylocarpus granatum

Two new harziane diterpenoids, named（9R,10R）-dihydro-harzianone（1） and harzianelactone（2）, were isolated from the endophytic fungus Trichoderma sp. Xy24 by using various column chromatography techniques. Their structures were determined on the basis of extensive spectroscopic（HR-ESI-MS, 1D NMR, 2D NMR and CD） analyses. Among them, 1 was the reductive product of harzianone and 2 was the Baeyer–Villiger monooxygenase catalyzed oxidation product of harzianone. Compound 1 exhibited cytotoxic activity against He La and MCF-7 cell lines with IC（50） values of 30.1 μmol/L and 30.7 μmol/L,respectively.