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 μm, and compound 2 exhibited weak cytotoxicity against SHSY5Y and MCF7 cells with IC50 values of 8.2 and 6.8 μm, respectively.