Effects of pulsed electric field on intracellular antioxidant activity and antioxidant enzyme regulating capacities of pine nut (Pinus koraiensis) peptide QDHCH in HepG2 cells

•A novel antioxidant peptide QDHCH was identified using HPLC-MS/MS.•The antioxidant activity of QDHCH was increased by PEF treatment.•The PEF-treated QDHCH have better protective oxidative stress inhibitory.•The secondary structures of QDHCH were influenced by PEF treatment.

Effects of pulse electric field (PEF) on antioxidant activity of pine nut (Pinus koraiensis) peptide were discussed using H2O2-induced HepG2 cells and changes of peptide structures were measured by MIR, NMR and CD spectra. Using HPLC-MS/MS, a novel peptide was identified as QDHCH. After PEF treatment the DPPH and ABTS radical inhibition, and CAA values of QDHCH were increased to 85.13% ± 0.17%, 95.45% ± 0.12%, and 4670.10 μmol of quercetin equivalents/100 g. The PEF-treated QDHCH has better protective oxidative stress inhibitory of 74.22 ± 3.70%, and the T-SOD, CAT, GSH-Px and GSH-Rx activities in cells were significantly increased by 91.92, 7.98, 18.5 and 18.79 U/mg prot, while the MDA content was decreased to 8.45 ± 0.71 U/mg prot compared with H2O2 damaged group. In addition, the hydroxyl radical scavenging activity of QDHCH was increased by 10.53%; the basic structure was not changed by PEF, while the influenced secondary structures may induce the antioxidant activity improvement in HepG2 cells.