Purification of peptide fraction with antioxidant activity from Moringa oleifera leaf hydrolysate and protective effect of its in vitro gastrointestinal digest on oxidatively damaged erythrocytes

Abstract

Moringa oleifera leaf (MOL) is an excellent source of high-quality plant protein. MOL hydrolysate (MOLH) was prepared by enzymatic hydrolysis and ethanol precipitation. The adsorption kinetics of SP-207 resin for antioxidant peptides from MOLH were studied. The adsorption process for antioxidant peptides on SP-207 was well described by the pseudo-second-order kinetics model. The adsorption was a multi-molecule layer adsorption process, which was exothermic. The peptide fraction with antioxidant activity (MOLP, 40% ethanol elution fraction) possessing high contents of antioxidant and hydrophobic amino acids was obtained by SP-207 column chromatography. A total of eight dipeptides including PR, L(I)K, L(I)H, L(I)P, L(I)L(I), GE, VL(I) and PF were identified in gastrointestinal digest of MOLP by UPLC-QTOF-MS/MS. The protective effects of MOLP digest and LH on oxidatively damaged erythrocytes by inhibition of MDA formation were comparable to that of GSH, indicating that MOLP could be used as an antioxidative ingredient in functional food.