A Comparative Study on Aflatoxin B₁ Metabolism in Mice and Rats

Abstract

in vivo metabolic studies on rats and mice revealed a marked difference in the fluorescent compounds produced after ingestion of aflatoxin B₁. The mouse converted aflatoxin B₁ to three unknown fluorescent compounds, designated x₁, x₂ and x₃ and the known aflatoxin M₁, while the rat was only capable of producing aflatoxin M₁. The results suggested that metabolites x₁, x₂, x₃ and aflatoxin M₁ were not part of a major metabolic pathway, but produced independently. These unknown yellowish-green fluorescent compounds did not seem to be conjugated with sulphate or glucuronic acid.

in vitro incubations of various mouse liver cell fractions with aflatoxin B₁ showed that metabolites x₁, x₂, x₃ and aflatoxin M₁, could only be produced by the microsomal fraction and that NADPH was needed as a co-factor. The differences in aflatoxin metabolism by mice and rats are discussed in relation to the apparent resistance of the mouse to the carcinogenic effects of this toxin.