Aflavinines and other antiinsectan metabolites from the ascostromata of Eupenicillium crustaceum and related species

Abstract

This report describes the distribution of antiinsectan metabolites present in sclerotioid ascostromata produced by representative strains of Eupenicillium crustaceum and fungal taxa that are considered to be closely related. The hexane and chloroform extracts of E. crustaceum NRRL 3332 displayed significant antiinsectan activity in assays against the corn earworm, Helicoverpa zea. The major metabolite accounting for this antiinsectan activity was a known aflavinine analog, 10,23-dihydro-24,25-dehydroaflavinine, occurring at approximately 2.8 mg/g of dry ascostromata. In dietary assays at ca. 3,000 ppm, a 79% reduction in weight gain and a 42% reduction in feeding rate were observed in H. zea and Carpophilus hemipterus larvae, respectively. A new aflavinine analog, 10,23,24,25-tetrahydro-24-hydroxyaflavinine, was also identified. These aflavinine compounds are the first to be reported from a fungal genus other than Aspergillus. New macrophorin-type metabolites accounted for the antiinsectan activity of ascostromata produced by E. crustaceum NRRL 22307, which produced no aflavinines, while Eupenicillium molle NRRL 13062 produced both aflavinines and macrophorins. Sclerotia produced by Penicillium gladioli NRRL 938, NRRL 939, and QM 2743, a fungus reported to be conspecific with the anamorph of E. crustaceum, produced neither aflavinines nor macrophorins. Eupenicillium reticulisporum NRRL 3446 produced the aflavinine analog 10,23-dihydro-24,25-dehydroaflavinine and an unrelated compound called pyripyropene A, a potent inhibitor of acyl-coenzyme A-cholesterol acyltransferase. Eupenicillium abidjanum NRRL 5809, reported to be conspecific with E. reticulisporum, produced neither of these compounds. The Eupenicillium species that produced aflavinines are also known for their ability to grow rapidly with reduced water activity.