Effect of Human Placenta Extract on Potassium Oxonate-Induced Elevation of Blood Uric Acid Concentration

Although anti-inflammatory effect of human placenta extract (HPE) was observed in rheumatoid arthritis and carrageenin-induced edema, effect of HPE on the arthritis of hyperuricemia and gout patients had never been examined. Excess uric acid is regarded to be a major risk factor in gout, renal diseases, cardiovascular diseases and cerebrovascular diseases. In our experiment, in order to investigate the effect of HPE on blood uric acid levels and xanthine oxidase (XO) activity, HPE 100 mg/kg was administered to the abdominal cavity of potassium oxonate-induced hyperuricemic mice. Blood uric acid levels and XO activity were measured 3 hr after administration. Furthermore, effect of HPE on in vitro superoxide anion generation in xanthine-XO system was also measured. In experimental mice, oxonate-induced significant elevation of blood uric acid levels was suppressed by the HPE administration similar to the allopurinol administration. Similarly, both in HPE-treated mice and in allopurinol-treated mice, blood XO activity was significantly reduced in comparison with vehicle-treated mice and oxonate-treated mice. Furthermore, there was significant positive correlation between blood uric acid levels and XO activity (p<0.01). In in vitro experiments, xanthine concentration was increased by the addition of HPE while simultaneously reducing uric acid concentration. These results indicate that HPE contains some XO inhibitors which reduce blood uric acid levels with inhibiting uric acid generation in purine metabolism. Then, XO inhibitors of HPE could be used in the treatment of hyperuricemia and gout patients to lower blood uric acid levels.