Antioxidant peptides from the sturgeon gill protein: purification, identification, molecular docking analysis and antioxidative mechanisms evaluation

Sturgeon gills, a by-product of sturgeon processing, constitute approximately 2% of the fish's total body weight but are largely underutilized, resulting in significant protein resource waste. This study aimed to isolate antioxidant peptides from sturgeon gill protein hydrolysates and evaluate their protective effects against oxidative damage in HepG2 cells. Using ultrafiltration, gel filtration, and RP-HPLC, 1,396 peptides were identified, among which FPGLP (FP5), GIPGF (GF5), and APDPF (AF5) showed the lowest binding energies to MPO (-8.6, -8.3, and -8.1 kcal/mol, respectively). These peptides significantly reduced intracellular ROS levels, and decreased cell apoptotic rates and inhibited ROS-mediated MAPK pathway phosphorylation. At 50 μM, FP5, GF5, and AF5 decreased ROS levels by 36.14%, 38.56%, and 33.75%, respectively, and suppressed phosphorylation of ERK, JNK, and p38. In conclusion, this study provides a theoretical basis for the high-value utilization of sturgeon by-products and their potential applications.