Cytotoxic naphtho- and benzofurans from an endophytic fungus Epicoccum nigrum Ann-B-2 associated with Annona squamosa fruits

Chemical exploration of the total extract derived from Epicoccum nigrum Ann-B-2, an endophyte associated with Annona squamosa fruits, afforded two new metabolites, epicoccofuran A ( 1 ) and flavimycin C ( 2 ), along with four known compounds namely, epicocconigrone A ( 3 ), epicoccolide B ( 4 ), epicoccone ( 5 ) and 4,5,6-trihydroxy-7-methyl-1,3-dihydroisobenzofuran ( 6 ). Structures of the isolated compounds were elucidated using extensive 1D and 2D NMR along with HR-ESI–MS. Flavimycin C ( 2 ) was isolated as an epimeric mixture of its two diastereomers 2a and 2b . The new compounds 1 and 2 displayed moderate activity against B. subtilis , whereas compounds ( 2 , 3 , 5, and 6 ) showed significant antiproliferative effects against a panel of seven different cancer cell lines with IC 50 values ranging from 1.3 to 12 µM.