Antihyperuricemic and xanthine oxidase inhibitory activities of Silymarin in a rat gout model

Introduction: Gout is a common metabolic defect spread around the world. It characterized by hyperuricemia, which resulting from the prolonged rise of uric acid (UA) levels in the blood, leading to increase the deposition of urate crystals in the joints and kidneys. The present study performed to investigate the efficacy of silymarin as antihyperuricemic agent. Materials and Methods: Enzyme assay was done using bovine milk xanthine oxidase (XO). The XO inhibitory activity in vitro was carried out using different doses of silymarin, and the degree of XO inhibition (XOI) was expressed as IC50. The antihyperuricemic of silymarin was investigated in the potassium oxonate-induced hyperuricemic rat model for 7 consecutive days of oral treatment of 10, 25, and 50 mg/kg doses. Results: The study results revealed that the silymarin has a potent activity of XOI with IC50 = 5.84 μg/mL as compared to standard drug, allopurinol IC50 = 1.85 μg/mL. In addition, these results showed that all doses of silymarin were able to be significant reduced serum UA levels in the hyperuricemic rats. Conclusion: Silymarin showed a significant effect on lowering the level of UA in the evaluated model, and therefore, it may be a promising agent for treating gout because of the possession of an antihyperuricemic effect through the inhibitory activity of xanthine oxide.