Tryptophan-containing milk protein-derived dipeptides inhibit xanthine oxidase

► W, WV and VW were shown to inhibit xanthine oxidase (XO) in a non-competitive fashion. ► W, WV and VW are 200 times less potent than Allopurinol a competitive drug of XO. ► Bovine lactoferrin (LF) hydrolyzed with gastrointestinal enzyme preparations generated W containing peptides could inhibit XO. ► Fractionation of a LF hydrolyzate with an activated carbon SPE cartridge allowed enrichment of W containing peptides. ► One SPE fraction enriched in W containing peptides was more potent than the hydrolyzate.