Abstract
In the previous paper, the authors reported the increase of rat-liver xanthine oxidase activity on oral administration of inosine, followed by the incorporation of riboflavin into the tissue. Further experiments were made for the elucidation whether the increased amounts of oral inosine supplementation ranging 1〜5mg/day are more effective, and it was found that there may be some positive significance in the enzymic system. Using the diet containing more than 15% of protein, the increase of the rat-liver xanthine oxidase activity was demonstrated, while it was non-effective in case of less than 15% of protein. When other purine nucleosides orally administrated, the increase of the rat-liver xanthine oxidase activity was also demonstrated, followed by somewhat accumulation of riboflavin in the tissue. Finally, metabolic fate of inosine was studied by estimating the urinary excretion of allantoin, uric acid and others. No urinary increase of uric acid while allantoin was always increased. From the above data, the authors have studied on the biological value allantoin/(urea×intake of protein), and it was concluded that inosine and related compounds may contribute to the induced enzymic reaction in rat-liver xanthine oxidase system.
