Purification of antioxidant peptides of Moringa oleifera seeds and their protective effects on H2O2 oxidative damaged Chang liver cells

Abstract

Eight novel and three known antioxidant peptides isolated from protein hydrolysate of Moringa oleifera seeds, using ultrafiltration, anion-exchange chromatography, gel filtration chromatography and reversed phase high performance liquid chromatography (RP-HPLC). The novel peptides were identified as Gly-Tyr (GY), Pro-Phe-Glu (PFE), Tyr-Thr-Arg (YTR), Phe-Gly (FG), Gln-Tyr (QY), Ile-Asn (IN), Ser-Phe (SF), Ser-Pro (SP), and the known peptides were identified as Tyr-Phe-Glu (YFE), Ile-Tyr (IY) and Leu-Tyr (LY), respectively, using protein amino acid sequence analyzer and electrospray ionization-mass spectrometry. All the eleven peptides exhibited strong scavenging activities on 2,2-Diphenyl-1picrylhydrazyl radical (DPPH) (EC50 2.28, 1.60, 1.77, 2.15, 0.97, 1.30, 0.75, 0.91, 1.21, 0.79, and 1.37 mg/L, respectively) and 2,2-azino-bis (3-ethylbenzothia zoline-6-sulfonic acid) diammonium salt radical (ABTS+) (EC50 1.03, 0.84, 0.95, 0.65, 0.37, 0.54, 0.33, 0.36, 0.67, 0.32 and 0.38 mg/mL, respectively). In addition, SF and QY showed protective effects on oxidative damage Chang liver cells induced by H2O2, and the contents of aspartate aminotransferase (ALT), alanine aminotransferase (AST) and malondialdehyde (MDA) decreased with the increasing concentrations of SF and QY. Furthermore, SF and QY could significantly increase the levels of superoxide dismutase (SOD) and catalase (CAT), thereby effectively scavenge reactive oxygen species (ROS) in H2O2-induced oxidative damaged Chang liver cells (P < 0.05). These results suggested that SF and QY had the ability to protect Chang liver cells from oxidative stress damage and might serve as potential antioxidants or oxidative damage cytoprotective agents used in pharmaceutical and health food industries.