Separation, identification and docking analysis of xanthine oxidase inhibitory peptides from pacific cod bone-flesh mixture

This study aimed to isolate and investigate five novel xanthine oxidase (XO) inhibitory peptides FF, YF, WPW, WPDARG and YNVTGW from alkaline protease hydrolyzate (F0) of Pacific cod processing by-product bone-flesh mixture (CBFM2). F0 was separated by dextran gel chromatography to obtain F1, F2, F3, F4 and F5 components. The components with the highest XO inhibitory activity were analyzed and identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the peptides were further screened by molecular docking using Autodock Vina. The results showed that the F4 component had the highest XO inhibitory activity, with a molecular weight ranging from 200 to 600 Da. Five novel XO inhibitory peptides FF, YF, WPW, WPDARG and YNVTGW were obtained with IC50 values of 0.80 mM, 0.52 mM, 1.68 mM, 0.40 mM and 0.23 mM, respectively. According to the results of molecular docking, peptides having at least one aromatic amino acid are more favorable to occupy the catalytic core of XO, reducing its catalytic activity. The amino acids Thr1010 and Phe914 in the XO active pocket interact with peptides. Overall, novel peptides from CBFM have the potential to be used as a natural uric acid reducing ingredient in functional and health foods.