New metabolic products of Aspergillus flavus. Part II. Asperflavin, anhydroasperflavin, and 5,7-dihydroxy-4-methylphthalide

Abstract

Asperflavin, a yellow pigment from the culture filtrate of an entomogenous strain of Aspergillus flavus, is shown to be (+)-3,4-dihydro-3,6,9-trihydroxy-8-methoxy-3-methylanthracen-1 (2H)-one (I; R = H). New minor metabolic products isolated were anhydroasperflavin (1,6-dihydroxy-8-methoxy-3-methyl-9-anthrone)(III; R¹= R³= H, R²= Me) and a lactone, shown to be 5,7-dihydroxy-4-methylphthalide (VIII; R¹= R²= H). The yellow spore-heads contained a mixture of the known fungal pigments aspergin (XII; R = n-C₅H₁₁·CH:CH·) and flavoglaucin (XII; R = n-C₇H₁₅).