Novel antioxidant peptides from bovine blood: Purification, identification and mechanism of action

The purpose of this study was to isolate, purify, identify, and characterize novel antioxidant peptides derived from bovine blood hydrolysates (BBH). Results showed that, BBH, obtained by two-step flavourzyme-alcalase hydrolysis, was used to obtain five fractions by ultrafiltration and gel filtration chromatography, where the Fraction B had the strongest antioxidant capacity. Five novel antioxidant peptides (GFAGDDAPRA, SGPGIHVR, APSADAPM, TQRFFESF and HVDPENFKLL) were identified utilizing RP-HPLC and LC-MS/MS, and exhibited excellent free radical scavenging ability. GFAGDDAPRA and TQRFFESF possessed the highest ABTS radical scavenging rate (95.70% and 93.20%, respectively), and the DPPH radical scavenging rate of APSADAPM was the highest (50.28%). Moreover, these five peptides could be docked with Recombinant Kelch Like ECH Associated Protein 1 (Keap1) with the binding energies less than −5 kcal/mol, which indicated that they may be able to promote the body's antioxidant capacity by activating the Keap1-Nrf2 signaling pathway of cell. Meaningfully, this work shed new light on the processing and utilization of bovine blood, as well as offered a valuable foundation for the study and development of food-borne antioxidant peptides.