Cytotoxic metabolites from the mangrove endophytic fungus Aspergillus sp. GXNU QG1a

A new benzoquinone, guxiumasperone A (1), and a new diisoprenyl-cyclohexene-type meroterpenoids, biscognienyne M (2), along with four known diisoprenyl-cyclohexene analogues was isolated from the mangrove endophytic fungus Aspergillus QG1a. Their structures were determined by extensive spectral analysis of 1D and 2D NMR, HR-ESI- MS, and X-ray crystallography. Compound 1 was deduced by a single-crystal X-ray diffraction analysis, and the absolute configuration of 2 was further unequivocally elucidated by comparing the experimental electronic circular dichroism (ECD) data with calculated ECD spectra. Compounds 1 and 2 showed significant cytotoxic activity against selected tumour cells. Particularly, compound 2 exhibited strong activity against A2780 cancer cells with an IC50 value of 6.8 μM.