Unraveling novel antioxidant peptides from Asian swamp eel: Identification, in silico selection, and mechanistic insights through quantum chemical calculation and molecular docking.

Fifteen novel antioxidant peptides were identified from Asian swamp eel (ASE) hydrolysate through in silico screening, demonstrating ABTS and ORAC activities ranging from 1.17 to 3.28 and 1.94 to 5.67 times higher than Trolox, respectively. Concurrently, four new sequences (AVLW, VWPS, VPWP, and HWDGSLPR) were discovered. The critical role of the hydrogen atom on the tryptophan indole nitrogen in ABTS radical scavenging was elucidated by quantum chemical calculations and subsequent active site methylation experiments, while the significance of hydrogen atoms on both the tryptophan indole nitrogen and tyrosine phenolic hydroxyl groups for ORAC values was emphasized. Moreover, molecular docking analysis demonstrated that ASE antioxidant peptides primarily interacted with myeloperoxidase (MPO) via hydrogen bonds with Arg405, Arg499, Arg590, Gln257, Glu268, His261, and Thr266, and electrostatic interactions with Arg405, Arg590, Glu268, His261, and His502, resulting in a tight binding to MPO.