Monascus-fermented black rice alleviates hyperuricemia through xanthine oxidase inhibition and metabolic regulation

Hyperuricemia (HUA) is a metabolic disorder closely associated with gout and renal dysfunction, highlighting the need for safe dietary strategies for its management. This study investigated whether Monascus fermentation enhances the anti-hyperuricemic potential of black rice. Monascus-fermented black rice extract (M-FBE) exhibited significantly stronger xanthine oxidase (XO) inhibitory activity in vitro than black rice extract (BE) and Monascus-fermented white rice extract (M-FWE). In a potassium oxonate/fructose-induced hyperuricemia mouse model, M-FBE markedly reduced serum uric acid levels, suppressed hepatic XO, adenosine deaminase and 5'-nucleotidase activities, and alleviated liver and kidney pathological damage. Serum metabolomics revealed that M-FBE restored metabolic homeostasis by regulating purine, glycerophospholipid and cholesterol metabolism. HPLC-UV analysis showed the accumulation of yellow pigment components corresponding to Monasfluore A and B after fermentation. These pigments may partly contribute to XO interaction and inhibition, as further supported by molecular docking and fluorescence quenching analysis. These findings indicate that Monascus fermentation enhances the urate-lowering activity of black rice through synergistic enzyme inhibition and metabolic regulation, highlighting Monascus-fermented black rice as a promising functional food for hyperuricemia management.