Hypouricemic and antioxidant activities of Allium cepa Lilliaceae and quercetin in normal and hyperuricemic rats

Objectives: To evaluate the hypouricemic and antioxidant effects of Allium cepa Lilliaceae (Allium cepa L.) and quercetin in normal and hyperuricemic rats. Methods: The following study was conducted in the Department of Nutrition and Biochemistry, Tehran University of Medical Science, Iran, between May 2007 and March 2008. A total of 48 male Wistar rats (body weights: 180-200 g) were randomly divided into 8 equal groups including normal; normal + Allium cepa L. (5g/kg); normal + quercetin (5mg/kg); normal + allopurinol (5mg/kg); hyperuricemic; hyperuricemic + Allium cepa L. (5g/kg); hyperuricemic + quercetin (5mg/kg); hyperuricemic + allopurinol (5mg/kg) once a day for 14 days. Experimentally, hyperuricemia in rats was induced by intraperitoneal injection of potassium oxonate (250mg/kg).Results: Allium cepa L. and quercetin treatments for 14 days significantly reduced (p=0.000) the serum uric acid levels of hyperuricemic rats in a time-dependent manner. All treatments significantly inhibited hepatic xanthine oxidase/xanthine dehydrogenase activity. Allium cepa L. and quercetin treatments led also to a significant improvement in biomarkers of oxidative stress in hyperuricemic rats (p=0.000). Although the hypouricemic effect of allopurinol was much higher than that of Allium cepa L. and quercetin, it could not significantly change oxidative stress biomarkers.Conclusion: These results may be responsible partly for the beneficial effects of Allium cepa L. and its major flavonoid on hyperuricemia and oxidative stress.