Screening and Antioxidant Activities Evaluation of Peptides From Abalone (Haliotis discus hannai Ino)

Marine organisms are rich in antioxidant peptides; however, extracting these peptides is time-consuming, labor-intensive, and costly, with sequence losses leading to uncertain results. This study aimed to identify abalone-derived antioxidant peptides with strong Keap1 binding ability and validate their antioxidative activities using a cellular oxidative damage model. We constructed an abalone-derived peptide library comprising 363 peptides using virtual enzymatic hydrolysis techniques. Of the 98 human Keap1 protein structures available in the protein data bank database, 2FLU was selected as the receptor. Using the CDOCKER module in Discovery Studio software, molecular docking was performed with the peptide library as ligands and 2FLU as the receptor, targeting the binding site at coordinates x: 5.000222, y: 7.103889 and z: 5.058000. Ten abalone-derived peptides with the strongest inhibition against Keap1-Nrf2 interaction were identified. A 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage model in human umbilical vein endothelial cells (HUVECs) was used to verify the molecular docking results and identified DEDEDEDK as the most active antioxidant peptide. DEDEDEDK interferes with Keap1-Nrf2 binding, significantly reducing reactive oxygen species levels in damaged cells, increasing superoxide dismutase and catalase activities, and elevated glutathione content, indicating its potential to mitigate AAPH-induced oxidative damage in HUVECs.