Studies on Glutathione S-Transferases of Aspergillus Flavus Group in Relation to Aflatoxin Production

Abstract

Aflatoxin synthesis in the mycelia of Aspergillus is positively correlated with the activity of cellular glutathione (GSH) S-transferases (Saxena, Manju, Mukerji, K.G., Raj, H.G. 1988, Biochem. J. 254, 567-570). This finding is further extended to the action of inducer and inhibitor of aflatoxin synthesis upon A. flavus GSH S-transferase. Phenobarbitone (PB) a known inducer of aflatoxin formation increases GST activity in toxigenic strain alone as compared to non-toxigenic strains. Tinaderm (Tolnaftate) an antifungal drug specifically inhibit aflatoxin synthesis. Tinaderm - treated A. flavus mycelium was found to have significantly diminished GSH S-transferase activity coupled with reduce levels of aflatoxin. These observations point out clearly that theendogenous aflatoxin is the main factor effecting specific induction of A. flavus GSH S-transferase. The inducing effect of aflatoxin appears to be different from phenobarbital pattern of induction of GSH S-transferase. In this connection, a direct interaction of aflatoxin with A. flavus genome similar to the action of TCDD is suggested.