Asperienes A-D, Bioactive Sesquiterpenes from the Marine-Derived Fungus Aspergillus flavus

Marine-derived fungi of the genera Aspergillus could produce novel compounds with significant bioactivities. Among these fungi, the strain Aspergillus flavus is notorious for its mutagenic mycotoxins production. However, some minor components with certain toxicities from A. flavus have not been specifically surveyed and might have potent biological activities. Our investigation of the marine-derived fungus Aspergillus flavus CF13-11 cultured in solid medium led to the isolation of four C-6'/C-7' epimeric drimane sesquiterpene esters, asperienes A-D (1-4). Their absolute configurations were assigned by electronic circular dichroism (ECD) and Snatzke's methods. This is the first time that two pairs of C-6'/C-7' epimeric drimane sesquiterpene esters have successfully been separated. Aperienes A-D (1-4) displayed potent bioactivities towards four cell lines with the IC50 values ranging from 1.4 to 8.3 mu M. Interestingly, compounds 1 and 4 exhibited lower toxicities than 2 and 3 toward normal GES-1 cells, indicating more potential for development as an antitumor agent in the future.