Purification, identification, and computational analysis of xanthine oxidase inhibitory peptides from kidney bean

Hyperuricemia is related to plenty of diseases, seriously damaging human health. Current clinical drugs used to treat hyperuricemia have many adverse effects. In this study, kidney bean hydrolysate (KBH) was found to exert high xanthine oxidase inhibitory (XOI) activity. Compared to KBH (50.31 +/- 2.73%), XOI activities of three fractions (M-w <5 kDa, M-w<3 kDa, M-w < 1 kDa) by ultrafiltration were higher and increased to 58.58 +/- 3.57%, 59.34 +/- 1.78%, and 55.05 +/- 5.00%, respectively (P < 0.05). A total of 69 peptides were identified by HPLC-ESI-MS/MS and analyzed binding affinities with XO with the help of molecular docking. AVDSLVPIGR, DWYDIK, LDNLLR, ISPIPVLK, ISSLEMTR showed well binding affinities with XO and DWYDIK presented the highest XOI activity (68.63 +/- 5.07%) among five synthetic peptides (P < 0.05). Additionally, visual analysis results indicated that DWYDIK was pushed into the hydrophobic channel and formed hydrogen bonds with pivotal amino acids of xanthine oxidase. Overall, KBH could be a promising candidate as anti- hyperuricemia functional food. Practical Application This research initially revealed that kidney bean peptides could significantly inhibit the activity of xanthine oxidase, indicating kidney bean peptides could be a treatment for hyperuricemia. Kidney bean peptides may have commercial potentials as a safer alternative with few side effects to drugs.

Automated summary

This study found that kidney bean hydrolysate has high xanthine oxidase inhibitory activity, with fractions obtained through ultrafiltration showing higher XOI activities. Several synthetic peptides exhibited good binding affinities with XO, with DWYDIK showing the highest XOI activity. The research suggests that kidney bean peptides could be a promising candidate for treating hyperuricemia.