Mechanistic insights into the impact of Maillard reaction products on endogenous antioxidant systems in fish muscle

• Maillard reaction products (MRPs) synergize with α-tocopherol to inhibit fish lipid oxidation. • MRPs enhance antioxidant activity in fish muscle through electron transfer with α-tocopherol. • MRPs protect the activity of endogenous antioxidant enzymes. • MRPs and α-tocopherol use complementary mechanisms to reduce various lipid pro-oxidants. The Maillard reaction products (MRPs) inhibit fish lipid oxidation; however, whether they act with the endogenous antioxidants in fish is unclear. This study investigated the effects of MRPs on the primary nonenzymatic endogenous antioxidants and endogenous antioxidant enzymes in carp meat, as well as their interaction mechanisms. The results showed a synergistic antioxidant effect of MRPs with α-tocopherol, which is the main nonenzymatic antioxidant in fish muscle. The synergistic mechanisms primarily included distribution differences, where MRPs and α-tocopherol exerted antioxidant effects in different media, and an electron transfer mechanism, where MRPs enhanced the antioxidant activity of α-tocopherol through electron transfer. Additionally, complementary enhancement occurred when MRPs and α-tocopherol used different molecular mechanisms to reduce various lipid pro-oxidants. Furthermore, MRPs protected the activities of endogenous antioxidant enzymes. These findings demonstrated that MRPs synergistically interacted with the endogenous antioxidants to inhibit oxidation and protect the related enzymes in fish, highlighting their antioxidant role in fish muscle.