Xylitol-induced increase in the concentration of oxypurines and its mechanism

We investigated the effect of xylitol on the plasma concentration and the urinary excretion of purine bases, 5-hydroxypyrazinamide and 5-hydroxypyrazinoic acid in subjects who had ingested pyrazinamide (60 mg/kg weight). One liter of 10% xylitol was infused intravenously over 2 hours to 5 subjects to whom pyrazinamide had been administered 10 hours before. Xylitol increased the plasma concentration of uric acid, hypoxanthine and xanthine, the urinary excretion of hypoxanthine and a ratio of lactic acid/pyruvic acid in blood, while it decreased the plasma concentration and the urinary excretion of inorganic phosphate, 5-hydroxypyrazinamide and 5-hydroxypyrazinoic acid. These results suggested that in addition to an increase in purine degradation by xylitol, xylitol-induced increase in the cytosolic NADH inhibited xanthine dehydrogenase activity in the liver and the small intestine.