Mechanism of flavonoids inhibiting xanthine oxidase and alleviating hyperuricemia from structure–activity relationship and animal experiments: A review

Hyperuricemia (HUA) is a metabolic disease caused by excessive uric acid in patients. Flavonoids have attracted extensive attention due to their safety, effectiveness, and little side effects in the treatment of HUA and inhibition of xanthine oxidase (XO) activity. In this paper, the studies on the treatment of HUA and the inhibition of XO activity by flavonoids (including flavones, flavonols, flavanones, flavanols, isoflavonoids, anthocyanins, and chalcones) were comprehensively reviewed from the aspects of structure–activity relationship and animal experiments. Results showed that hydrogen bonds and hydrophobic interactions were the two most important forces involved in the interaction between flavonoids and XO. Flavonoids could combine with the hydrophobic cavity of XO to cause changes in XO structure and influence the action of enzyme and substrate, thereby decreasing the catalytic activity of XO. Moreover, flavonoids undergo a series of metabolic reactions in the organism, which plays a role in alleviating HUA by affecting the expression of related genes and proteins (e.g., glucose transporter 9, urate transporter 1, and organic anion transporter 1) in the kidneys, liver, and intestinal tract of the organism and changing the internal environment in organs. In addition, this paper provides new perspectives on the shortcomings of the current research, to promote the in‐depth development and application of flavonoids.