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

Abstract

Summary

1. Weanling rats fed diets deficient in protein or riboflavin for 2 to 4 weeks had liver riboflavin levels that were reduced approximately 40% and 55% respectively; the corresponding reduction in intestinal riboflavin was approximately 15% and 55%. About 60% of the riboflavin in normal liver was in the sedimentable particles (nuclei plus mitochondria plus microsomes), and the above loss of riboflavin was proportionately the same from both the particulate and supernatant fractions. 2. The 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 amount of riboflavin bound in xanthine oxidase represents only a very small fraction of the total riboflavin present. Liver xanthine oxidase was decreased only 25% by a riboflavin deficient diet.