Xanthine Oxidase Inhibitory Peptide from Distiller’s Grains: Virtual Screening and Uric Acid-Lowering Effect

To achieve high-value utilization of distiller’s grains, this study explored xanthine oxidase (XOD) inhibitory peptides from distiller’s grains and determined their anti-hyperuricemic effect in mice.

Potential XOD inhibitory peptides from an enzymatic hydrolysate of distiller’s grains were isolated by ultrafiltration and identified by liquid chromatography-mass spectrometry (LC-MS) and in silico analysis. The action mechanism of XOD inhibitory peptides was elucidated using molecular docking, and the anti-hyperuricemic effect in mice was evaluated.

The < 1 kDa fraction exhibited the highest XOD inhibitory activity. Four XOD inhibitory peptides were obtained, namely WDLPF, WPQ, WFPE, and LQKW. Among them, LQKW demonstrated the highest activity, with a half maximal inhibitory concentration (IC₅₀) of 2.70 mg/mL. After gastrointestinal digestion, (61.84 ± 0.82)% of its activity remained. Molecular docking revealed that LQKW primarily bound to the receptor protein 1FIQ through hydrogen bonds and hydrophobic interactions. Compared with the model group, low-, medium-, and high-dose (200, 400, and 800 mg/kg) LQKW significantly (P < 0.01) reduced serum uric acid levels by 32.59%, 35.96%, and 37.28%, respectively. Additionally, medium- and high-dose LQKW significantly (P < 0.01) decreased kidney index, creatinine, and blood urea nitrogen levels while markedly alleviating renal pathological damage in hyperuricemic mice.

The distiller’s grain-derived XOD inhibitory peptide LQKW exerts its inhibitory activity by binding to 1FIQ via hydrogen bonds and hydrophobic interactions, thereby effectively reducing serum uric acid levels in HUA mice and providing renal protection. This study provides theoretical support for the development of anti-hyperuricemic peptides from distiller’s grains.