Effects of quercetin and kaempferol versus allopurinol on serum uric acid levels, biomarkers of oxidative stress and hepatic xanthine oxidase/xanthine dehydrogenase activity in hyperuricemic rats

Objectives: The aim of this study was to investigate the effect of oral administration of quercetin (5 mg/kg) and kaempferol (5 mg/kg) versus allopurinol (5 mg/kg) on serum uric acid levels, biomarkers of oxidative stress (total antioxidant capacity and malondialdehyde concentration) and liver xanthine oxidase/xanthine dehydrogenase activity in normal and hyperuricemic rats. Methods: A total of 48 male Wistar rats (body weights: 180-200 g) were randomly divided into eight equal groups including normal; normal + quercetin (5 mg/kg); normal + kaempferol (5 mg/kg); normal + allopurinol (5 mg/kg); hyperuricemic; hyperuricemic + quercetin (5 mg/kg); hyperuricemic + kaempferol (5 mg/kg); hyperuricemic + allopurinol (5 mg/kg) once a day for 14 days. Experimentally hyperuricemia in rats was induced by intraperitoneal injection of potassium oxonate (250 mg/kg). Results: Quercetin and kaempferol treatments for 14 days significantly reduced the serum uric acid levels of hyperuricemic rats in a time- dependent manner. All treatments significantly inhibited hepatic xanthine oxidase/xanthine dehydrogenase activity. Quercetin and kaempferol treatment led also to a significant improve in biomarkers of oxidative stress in hyperuricemic rats. Although the hypouricemic effect of allopurinol was much higher than that of quercetin and kaempferol, it could not significantly change oxidative stress biomarkers. Conclusion: The results indicate that these polyphenols could be as possible alternative for allopurinol, and/or as therapeutic supplements to minimize the side effects of allopurinol in treating hyperuricemia and oxidative stress diseases.