Effect of Aflatoxin on the Biosynthesis of Vitamin A

Abstract

Patients of vitamin A deficiency are frequently found in the Southeast Asia. Aflatoxin, a kind of toxin contained in some tropical foods, affects in the inhabitants of the same area. In this experiment, we tried whether the biosynthesis of vitamin A is inhibited by aflatoxin or not. Male rats, weighing about 70g, were administered 4mg of aflatoxin B₁ per kg body weight intraperitoneally. Rats were killed and their livers were removed, homogenized by Potter's homogenizer. Liver homogenate obtained was centrifuged at 3, 000r.p.m. and the supernatant was used as enzyme solution. Reaction mixture consisted of 0.8ml of enzyme solution, 1mg of β-carotene. 10μmoles of glutathione, 30μmoles of nicotinamide, 12μmoles of sodium taurocholate, 1mg of α-tocopherol and 200μmoles of potassium phosphate buffer, pH 7.7. After 60min incubation at 37°, the reaction mixture was shaken with chloroform. Vitamin A synthesized from β-carotene was extracted into chloroform. Amount of vitamin A was assayed spectrophotometrically. The results of experiment showed that aflatoxin inhibited the conversion of β-carotene into vitamin A. It is concluded that the chronic intoxication of aflatoxin has a tendency to cause vitamin A deficiency.