The Fly Maggot Antioxidant Peptide (FMP) Alleviates Oxidative Damage in the Intestines of Weaned Piglets by Enhancing Mitochondrial Autophagy Through Activation of the Nrf2 Signaling Pathway

Intestinal oxidative stress severely compromises the health and growth of weaned piglets. The fly maggot-derived antioxidant peptide FMP was previously identified, but its protective mechanisms remain unclear. Here, we explored how FMP alleviates oxidative intestinal injury. In IPEC-J2 cells, FMP pretreatment significantly attenuated H2O2-induced cytotoxicity, ROS accumulation, and apoptosis, while enhancing antioxidant enzyme activities and activating Nrf2 signaling (p < 0.05). Co-treatment with the Nrf2 inhibitor ML385 abolished FMP-mediated mitophagy enhancement and cytoprotection, revealing that FMP enhances PINK1/Parkin-dependent mitophagy via Nrf2 activation. In diquat-challenged weaned piglets, oral FMP administration restored serum SOD and GSH-Px activities, reduced MDA and DAO levels (p < 0.05), upregulated jejunal tight junction proteins, and enriched Lactobacillus populations. These findings demonstrate that FMP targets the Nrf2-mitophagy axis to protect against intestinal oxidative damage, supporting its application as a green feed additive.