Cytoprotective Effect of Antioxidant Pentapeptides from the Protein Hydrolysate of Swim Bladders of Miiuy Croaker (Miichthys miiuy) against H2O2-Mediated Human Umbilical Vein Endothelial Cell (HUVEC) Injury

In our previous research, ten antioxidant pentapeptides including FYKWP, FTGMD, GFEPY, YLPYA, FPPYERRQ, GFYAA, FSGLR, FPYLRH, VPDDD, and GIEWA were identified from the hydrolysate of miiuy croaker (Miichthys miiuy) swim bladder. In this work, their protective function on H2O2-induced oxidative damage to human umbilical vein endothelial cells (HUVECs) was studied. Results indicated that there was no significant difference in the HUVEC viability between the normal group and the treated groups with the 10 pentapeptides at the concentration of 100 μM for 24 h (p < 0.05). Furthermore, FPYLRH of 100 μg/mL extremely significantly (p < 0.001) increased the viability (80.58% ± 5.01%) of HUVECs with H2O2-induced oxidative damage compared with that of the model group. The protective mechanism indicated that FPYLRH could extremely significantly (p < 0.001) increase the levels of superoxide dismutase (SOD) (211.36 ± 8.29 U/mg prot) and GSH-Px (53.06 ± 2.34 U/mg prot) and decrease the contents of reactive oxygen species (ROS) (139.1 ± 11.8% of control), malondialdehyde (MDA) (13.66 ± 0.71 nM/mg), and nitric oxide (NO) (4.36 ± 0.32 µM/L) at the concentration of 100 μM in HUVECs with H2O2-induced oxidative damage compared with those of the model group. In addition, FPYLRH dose-dependently protected DNA in oxidative damage HUVECs model. These results suggested that FPYLRH could significantly attenuate the H2O2-induced stress injury in HUVECs and might be used as a potential natural antioxidant in the functional food industries.