Brassica rapa L. (Turnip) Ethanol Extract Alleviates Hyperuricemia by Modulating Purine Metabolism Enzymes and Renal Urate Transporters

Hyperuricemia (HUA) is a metabolic disorder caused by excessive uric acid (UA) production and/or insufficient UA excretion. Brassica rapa L. (turnip) is a traditional medicinal and edible plant in northwestern China. In this study, the urate-lowering effects of B. rapa L. ethanol extract (BrEE) and associated underlying mechanisms were investigated using a hypoxanthine/potassium oxonate-induced HUA mouse model and UA-stimulated HK-2 cells. BrEE was prepared and characterized; quercetin-3-glucuronide was the most abundant compound in BrEE, with a relative abundance of 22.04%. BrEE significantly lowered serum UA levels and improved renal function in mice. Key UA-producing enzymes, xanthine oxidase (XOD) and adenosine deaminase (ADA), were suppressed and renal UA transporters were modulated to enhance excretion: URAT1 and GLUT9 were downregulated and ABCG2 was upregulated. These results indicated that BrEE’s protective effects were associated with its regulatory effects on UA transport-related protein expression. BrEE also alleviated oxidative stress, and reduced inflammation and renal pathology. Meanwhile, molecular docking predicted favorable binding between the major BrEE constituents and XOD or URAT1, providing preliminary support for their potential interactions with these targets. Thus, BrEE exerted multi-target urate-lowering and kidney-protective effects, providing preliminary evidence for the potential of B. rapa L. as a plant-derived resource for further investigation in the development of functional food ingredients to regulate urate metabolism.