Cytotoxic metabolites from the mangrove endophytic fungus GXNU QG1a.

A new benzoquinone, guxiumasperone A (), and a new diisoprenyl-cyclohexene-type meroterpenoids, biscognienyne M (), along with four known diisoprenyl-cyclohexene analogues was isolated from the mangrove endophytic fungus QG1a. Their structures were determined by extensive spectral analysis of 1D and 2D NMR, HR-ESI- MS, and X-ray crystallography. Compound was deduced by a single-crystal X-ray diffraction analysis, and the absolute configuration of was further unequivocally elucidated by comparing the experimental electronic circular dichroism (ECD) data with calculated ECD spectra. Compounds and showed significant cytotoxic activity against selected tumour cells. Particularly, compound exhibited strong activity against A2780 cancer cells with an IC value of 6.8 M.