Two new isocoumarins isolated from a mangrove-derived Penicillium sp.

Two new isocoumarins named peniciisocoumarins I and J (1−2), together with four known analogues (3−6), were obtained from Penicillium sp. GXIMD 03001, an endophytic fungus derived from the rhizophoraceous mangrove Kandelia candel. The structures and absolute configurations of 1 and 2 were determined by detailed analysis of their NMR, MS spectroscopic data, a modified Mosher’s method and electronic circular dichroism data. All isolated isocoumarins were evaluated for their cytotoxic activity against four human cancer cell lines (SPCA-1, BEL-7402, GSC-7901 and MCF-7). However, none of the compounds exhibited any appreciable activity (IC50 > 50 μM).