The Effect of Diet on Riboflavin and Xanthine Oxidase in Rat Liver and Intestine.

Abstract

Weanling rats fed diets deficient in protein or riboflavin for 2-4 weeks had their liver riboflavin levels reduced approx. 40% and 55%, intestinal riboflavin by 15% and 55%. About 60% of the riboflavin in normal liver was in the sedimentable particles (nuclei plus mitochondria plus microsomes), and the loss of riboflavin was proportionately the same from both the participate and the supernatant fractions. Incorporation of soy flour in the diet as a source of the unidentified xanthine oxidase factor had no effect on the total riboflavin content of the liver or intestine, but did increase the liver and intestinal xanthine oxidases 30% and 170%, respectively. The amt. of riboflavin bound in xanthine oxidase represented only a small fraction of the total riboflavin present. Liver xanthine oxidase was decreased only 25% by a riboflavin-deficient diet.