Mark R. TePaske

Sclerotial metabolites of Aspergillus Flavus toxic to a detritivorous maize insect (Carpophilus Hemipterus, Nitidulidae)

The fungal sclerotium represents an important survival structure in the life cycle of many fungi, including Aspergillus flavus . Purified sclerotial metabolites from a non-aflatoxigenic strain of A. flavus (NRRL 6541) showed substantial antifeedant activity against Carpophilus hemipterus (Nitidulidae). This insect is known to encounter A. flavus sclerotia that form naturally in both standing and downed maize ears. The most abundant active component was dihydroxyaflavinine, but one novel analogue of dihydroxyaflavinine and a third unrelated metabolite, compound ‘1’ were also found to deter Carpophilus feeding when incorporated into a pinto bean diet at 100 p.p.m. d.w. Naturally occurring levels of each of these metabolites were found to be higher than 100 p.p.m. in A. flavus sclerotia. Arthropod predation is recognized as a selective force that has shaped the chemical defence systems of A. flavus and other sclerotium-producing fungi.

Leporin A: an antiinsectan N-alkoxypyridone from the sclerotia of Aspergillus leporis

Abstract Leporin A (5), an antiinsectan N-methoxy-2-pyridone, was isolated from the sclerotia of Aspergillus leporis. The structure was determined through analysis of various 1D- and 2D-NMR experiments. Two previously reported aflavinine derivatives (3 and 4) were also isolated from this source.

The structure of tubingensin B: A cytotoxic carbazole alkaloid from the sclerotia of Aspergillus tubingensis

Tubingensin B (4), a cytotoxic carbazole alkaloid with a novel ring system, was isolated from the sclerotia of the fungus . The structure was assigned primarily on the basis of selective INEPT, homonuclear decoupling, and COSY experiments.

Three new aflavinines from the sclerotia of aspergillus tubingensis

Abstract Three new metabolites with the aflavinine ring system (2–4) have been isolated from the sclerotia (key survival structures) of the fungus Aspergillus tubingensis (NRRL 4700), and their structures were assigned primarily through NMR studies. Carbon and proton NMR assignments for these compounds are presented, and the antiinsectan activity of one of the compounds (4) is described.