Flavonoids: An Outstanding Structural Core for the Inhibition of Xanthine Oxidase Enzyme

Context: Xanthine oxidase is a key enzyme in purine metabolism with an important role in various pathological conditions including gout and oxidative stress. Many of the synthetic candidates showed remarkable activity with a greater amount of side effects. Thus the search of promising structural core like flavonoids emerged greater attention for the inhibition of xanthine oxidase. Objective: The objective of this review is to provide a detailed knowledge of the flavonoidal class of compounds including natural and synthetic derivatives for the inhibition of xanthine oxidase. The review lays emphasis on the structure activity relationship and the scope of computational chemistry for designing flavonoids which inhibit xanthine oxidase. Methods: This review has been constructed by the most reliable literature databases including ScienceDirect, PubMed, Bentham Science and American Chemical Society Publishers. Results: The flavonoidal class of compounds was found to exhibit remarkable xanthine oxidase inhibitory activity. In addition, structure–activity relationships, molecular descriptors and enzyme-drug interactions of the flavonoids binding to the active site of xanthine oxidase were discussed, which is required for further rational drug design. Conclusion: It has been concluded that molecular recognition of a flavonoidal class of compound's inhibitory activity of the xanthine oxidase enzyme mainly depends on the planar nature of benzopyran ring, hydroxyl group at C-5 and C-7 position and torsion angle formed by the C3-C2-C1'-C2'. Keywords: Docking, flavonoids, quercetin, xanthine oxidase.