Effect of dietary purine restriction, allupurinol, and oxipurinol on urinary excretion of ultraviolet-absorbing compounds.

We demonstrate that purine restriction is associated with a decreased excretion of a number of uv-absorbing compounds-including uric acid, hypoxanthine, xanthine, adenine, pseudouridine, and 5-acetylamino-6-amino-3methyluracil-indicating that these compounds originate, at least partly, exogenously. Administration of allopurinol and oxipurinol is associated with a decreased excretion of uric acid and an increased excretion of hypoxanthine and xanthine, as well as the excretion of the previously identified products of allopurinol and oxipurinol metabolism. Moreover, these drugs further decrease excretion of 5-acetylamino-6-amino-3-methyluracil, increase uracil excretion slightly, and strikingly increase orotic acid and orotidine excretion. No change in pseudouridine excretion was observed. The ultraviolet-analyzer is a valuable tool for detecting qualitative changes in the excretion of ultraviolet-absorbing compounds in the urine; with it, identified peaks can be semiquantitated.