Production and transepithelial transportation of casein-derived peptides and identification a novel antioxidant peptide LHSMK

Abstract In this study, casein derived peptides were hydrolyzed with trypsin and then transported across Caco-2 cell monolayers to choose intestinal absorbable antioxidant peptides. E/S ratio at 5.45 %, pH at 7.13 and temperature at 51.99 °C were found to be the optimal conditions for enzymatic hydrolysis of casein by trypsin by Response Surface Method. The fraction below 10 kDa purified by the hollow fiber ultrafiltration membrane was applied to Sephadex G-10 gel filtration chromatography, and the obtained components were transported across the Caco-2 cell monolayer. The transported peptides were detected on the basolateral side of the Caco-2 cell monolayer using ultra-performance liquid chromatography-tandem mass spectrometry. It was found that LHSMK was an unreported pentapeptide. The synthetic peptide LHSMK had free radical scavenging ability, and the antioxidant activity exhibited a dose-dependent increase. Furthermore, LHSMK can also regulate antioxidant enzymes activity in oxidative-damage cells. This study provides a method for the preparation of intestinal absorbable peptides, and provides basic research for the development of functional food market.