Protection of lung fibroblast MRC-5 cells against hydrogen peroxide-induced oxidative damage by 0.1-2.8 kDa antioxidative peptides isolated from whey protein hydrolysate

Antioxidative peptides (0.1-2.8 kDa) obtained from gel filtration of Alcalase-hydrolysed whey protein were subjected to individual peptide isolation by RP-HPLC. The sub-fraction P4 and a prominent pentapeptide identified by mass spectrometry (Val-His-Leu-Lys-Pro) (P4c) were found to be highly antioxidative, therefore, used to assess the efficacy against hydrogen peroxide (H ₂O₂)-induced human lung fibroblast MRC-5 cell oxidative injury. MRC-5 cells were damaged by incubation with H₂O₂, but cell death was significantly reduced when exposed to P4 and P4c (P < 0.05). Compared to the H₂O₂-damaged model control, P4 and P4c enhanced the activity of cell superoxide dismutase, glutathione peroxidase, and catalase, and decreased the levels of malonaldehyde (P < 0.05). These results, with a more pronounced action of P4c than P4, demonstrated that antioxidative peptides had a significant protection of MRC-5 cells against the toxicity caused by H₂O₂.