Abstract
Introduction: Gout is a chronic metabolic disease in which xanthine oxidase plays a crucial role. Many natural compounds such as various flavonoids have been reported to have inhibitory effect on xanthine oxidase. In this study we aimed to screen hydromethanol extracts of various plants for their anti-xanthine oxidase activity to find safer and cheaper medicines in prevention and control of related diseases.Methods: The xanthine oxidase activity was measured by spectrophotometric method at 290 nm. Kinetic study of the enzyme was performed in presence and absence of the extracts.Results: Among sixty hydromathanolic (70% methanol) extracts, Quercus infectoria and Mentha longifolia showed more than 70% inhibitory effect on xanthine oxidase. M. longifolia showed competitive inhibition and Q. infectoria showed non-competitive inhibition by double-reciprocal Lineweaver-Burk plot analysis. The Km value of xanthine for xanthine oxidase was 1.81 mM and Vmax value was 2.01 mM min-1.Conclusion: The data suggest that these plants might be good candidates for treatment of gout disease.