Vermistatin derivatives with α-glucosidase inhibitory activity from the mangrove endophytic fungus Penicillium sp. HN29-3B1.

Three new vermistatin derivatives, 6-demethylpenisimplicissin ( 1 ), 5′-hydroxypenisimplicissin ( 2 ), and 2′′-epihydroxydihydrovermistatin ( 3 ), along with five known vermistatin analogues, methoxyvermistatin ( 4 ), vermistatin ( 5 ), 6-demethylvermistatin ( 6 ), hydroxyvermistatin ( 7 ), and penisimplicissin ( 8 ), were isolated from the culture of the mangrove endophytic fungus Penicillium sp. HN29-3B1 from Cerbera manghas . Their structures were elucidated mainly by nuclear magnetic resonance spectroscopy. The absolute configurations of compounds 1 and 2 were deduced on the basis of circular dichroism data. The absolute structures of compounds 3 and 5 were confirmed by a single-crystal X-ray diffraction experiment using Cu K α radiation. In the bioactivity assay, compounds 1 and 3 exhibited α -glucosidase inhibitory activity with IC 50 values of 9.5 ± 1.2 and 8.0 ± 1.5 µM, respectively. The plausible biosynthetic pathways for all compounds are discussed.