Protective effect of antioxidant peptides from grass carp scale gelatin on the H2O2-mediated oxidative injured HepG2 cells

•Protective effect of GSGH on H2O2-oxidative injured HepG2 cells was investigated.•Most of peptides were low molecular weight peptide at 358–986 Da.•Synergistic effect existed among peptides and contributed to antioxidant activity.•SOD, CAT and GPX activities increased, while ROS level and MDA content decreased.•The damage on cell membrane and DNA were weaken with GSGH pretreatment. The protective effect of antioxidant peptides from grass carp scale gelatin on hydrogen peroxide (H2O2)-mediated oxidative injured HepG2 cells was investigated, and the protective mechanism as well as peptide structure were studied. Pretreated with grass carp scale gelatin hydrolysates (GSGH) for 24 h significantly increased the survival rates and decreased the apoptosis rates of H2O2-mediated oxidative injured HepG2 cells. The increase in SOD, CAT and GPX activities, reduce in ROS level and MDA content, and weaken in damage on cell membrane and DNA could be responsible for the protective effect of GSGH on H2O2-mediated oxidative injured HepG2 cells. Peptide sequences of GSGH were analyzed by LC-ESI-Q-Orbitrap-MS/MS, and results showed that most of them were low molecular weight peptide at 358–986 Da. Synergistic effect existed among antioxidant peptides and contributed to the strong antioxidant activities of GSGH.