Versicolols A and B, two new prenylated isocoumarins from endophytic fungus Aspergillus versicolor and their cytotoxic activity

Versicolols A and B (1 and 2), two rare prenylated isocoumarin derivatives, along with five known isocoumarins (3-7) were isolated from the fermentation products of an endophytic fungus Aspergillus versicolor. Their structures were elucidated on the basis of extensive spectroscopic analysis, including 1D- and 2D-NMR techniques. Compounds 1 and 2 were evaluated for their cytotoxicity against five human tumor cell lines. The results showed that compounds 1 exhibited weak cytotoxicity against A549 and MCF7 cells with IC50 values of 9.4 and 8.8 mu m, and compound 2 exhibited weak cytotoxicity against SHSY5Y and MCF7 cells with IC50 values of 8.2 and 6.8 mu m, respectively.