MFG-E8-derived antioxidant peptides attenuate dexamethasone-induced skeletal muscle metabolic dysfunction via PI3K/Akt-GLUT4-PPARα signaling pathway.

Oxidative stress and mitochondrial dysfunction are key features of sarcopenia-related skeletal muscle metabolic dysfunction. This study aimed to identify MFG-E8-derived bioactive peptides with antioxidant and metabolic regulatory potential. Integrated bioinformatics analysis highlighted oxidative phosphorylation, thermogenesis, ROS-related pathways and lipid metabolic regulation as major molecular features of sarcopenia-related metabolic dysfunction. After simulated gastrointestinal digestion of bovine milk fat globule epidermal growth factor 8 (MFG-E8), 98 peptides were identified by LC-MS/MS. Candidate peptides were prioritized using peptidomics, ADMET prediction, molecular docking, Caco-2 monolayer-based transepithelial transport assessment and L6 cell-based validation. Among the selected peptides, YAR showed a favorable multi-target docking profile with Akt, PPARα and SIRT1, together with putative transepithelial transport potential in a Caco-2 monolayer model. and its detection in basolateral fractions after Caco-2 monolayer transport. In dexamethasone-injured L6 myoblasts, YAR displayed the strongest cytoprotective activity, reducing intracellular ROS by up to 52.6%, stabilizing mitochondrial membrane potential, and increasing total Akt and p-Akt fluorescence intensities by 30% and 32%, respectively. YAR also partially restored PI3K/Akt signaling and modulated downstream metabolic effectors, including GLUT4 and PPARα. These findings identify YAR as a promising MFG-E8-derived antioxidant peptide with potential transepithelial transport and cytoprotective activity, providing a mechanistic basis for developing food-derived peptides targeting oxidative stress-related skeletal muscle metabolic dysfunction.