New metabolic products of Aspergillus flavus. Part I. Asperentin, its methyl ethers, and 5′-hydroxyasperentin

Abstract

Asperentin, a minor metabolic product of an entomogenous strain of Aspergillus flavus grown in surface culture on synthetic media, has been shown to be 3,4-dihydro-6,8-dihydroxy-3-(6-methyltetrahydropyran-2-ylmethyl)isocoumarin (I; R¹= R²= H). The major secondary metabolic product formed under these conditions was the 8-O-methyl ether (I; R¹= H, R²= Me); additional minor products were the 6-O-methyl ether and three closely-related phenolic compounds, one of which was shown to be a 5′-hydroxyasperentin (III; R¹= R²= H, R³= OH).