Cytotoxic tremulanes and 5,6-secotremulanes, four new sesquiterpenoids from a plant-associated fungus X1-2
Two new tremulanes and two new 5,6-secotremulanes, davotremulanes A-D 1–4, along with four known compounds 5–8, were isolated from the culture extract of X1-2, an unidentified plant-associated fungus, which was isolated from the endangered plant, Davidia involucrate Baill. in Shennongjia District. The structures of new compounds 1–4 were established on the basis of extensive spectroscopic analysis. Compounds 1–8 were evaluated for cytotoxic activity to four cancer cell lines, and compounds 1, 2 and 5 displayed selectively moderate activities to A549 cell line with IC50 at 15.3, 25.2, 35.2 μg/mL.