Xanthones and sesquiterpene derivatives from a marine-derived fungus Scopulariopsis sp.

Abstract

Two new xanthone derivatives, 12-dimethoxypinselin (1) and 12-O-acetyl-AGI-B4 (2), as well as two new phenolic bisabolane-type sesquiterpenes, 11,12-dihydroxysydonic acid (15) and 1-hydroxyboivinianic acid (16), together with one new alkaloid, scopulamide (21) and one new α-pyrone derivative, scopupyrone (26), in addition to twenty-three known compounds (3–14, 17–20, 22–25, 27–29) were isolated from solid rice cultures of the marine-derived fungus Scopulariopsis sp. obtained from the Red Sea hard coral Stylophora sp. All compounds were unambiguously identified through extensive NMR spectroscopic analyses, and by comparison with the literature. Marfey's reaction was performed to determine the absolute configuration of scopulamide (21) and TDDFT-ECD calculations were used to assign the configuration of AGI-B4 (3) and scopupyrone (26). All isolated compounds were evaluated for their cytotoxicity against L5178Y mouse lymphoma cells and the structure-activity relationships were discussed.