Preparation of Antioxidant Peptide by Microwave- Assisted Hydrolysis of Collagen and Its Protective Effect Against H(2)O(2)-Induced Damage of RAW264.7 Cells

Antioxidant peptides have elicited interest for the versatility of their use in the food and pharmaceutical industry. In the current study, antioxidant peptides were prepared by microwave-assisted alkaline protease hydrolysis of collagen from sea cucumber (Acaudina molpadioides). The results showed that microwave irradiation significantly improved the degree of hydrolysis of collagen and the hydroxyl radical (OH⋅) scavenging activity of hydrolysate. The content and OH⋅ scavenging activity of collagen peptides with molecular weight ≤ 1 kDa (CP(S)) in the hydrolysate obtained at 250 W increased significantly compared with the non-microwave-assisted control. CP(S) could scavenge OH⋅ and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in a dose-dependent manner. The scavenging activity of OH⋅ and DPPH radical was 93.1% and 41.2%, respectively, at CP(S) concentration of 1 mg/mL. CP(S) could significantly promote RAW264.7 cell proliferation and reduce the Reactive Oxygen Species (ROS) level of H(2)O(2)-induced damage in RAW264.7 cells in a dose-dependent manner. Furthermore, all CP(S)-treated groups exhibited an increase in superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and a decrease in malondialdehyde (MDA) level compared with the control. These results showed that CP(S) could effectively protect RAW264.7 cells from H(2)O(2)-induced damage, implying the potential utilization of CP(S) as a natural antioxidant for food and pharmaceutical applications.