Effects of Plastein Reaction Mediated Corn Glutelin Hydrolysate on the Structure and Its Anti‐Inflammatory Activity of ARPE‐19 Cells in Vitro

Corn glutelin hydrolysate (CGH) has demonstrated potential diverse biological activities; however, its application in the food industry is often limited by physicochemical properties (e.g., peptide instability, solubility, or essential amino acid deficiency). The Plastein reaction, a very safe chemical reaction, involving exogenous amino acids (AAs), shows promise in altering the functionality of CGH. In this study, CGH was modified via the Plastein reaction using histidine, cysteine, or tryptophan to generate CGH-His, CGH-Cys, and CGH-Trp. These modified products with superior antioxidant activity and functional characteristics were screened out, and their anti-inflammatory activity was evaluated via an LPS-induced retinal inflammation ARPE-19 cell model. The results indicated that the free amino group contents of all three AA-modified CGHs were significantly lower than those of their corresponding mixtures (P < 0.05). Among the modifiers, CGH-Trp exhibited a significantly enhanced DPPH radical scavenging rate (78.66%), hydroxyl radical scavenging rate (58.35%), ABTS radical scavenging rate (83.29%), and average particle size (381.67 nm) (P < 0.05), compared to unmodified CGH. Structural characterization analysis revealed that the incorporation of tryptophan led to peptide condensation and improved thermal stability. Furthermore, pre-treatment with 10 µg/mL of CGH-Trp significantly reduced the secretion of TNF-α, IL-6, and IL-1β by 33.46%, 32.17%, and 44.49%, respectively, in ARPE-19 cells, compared to the LPS-induced group. This study confirms that the Plastein reaction promotes peptide condensation in CGH in the presence of exogenous amino acids and improves the characteristic, antioxidant, and anti-inflammatory activities, highlighting its potential as a preventive strategy for age-related macular degeneration (AMD).