Preparation, separation, and identification of antioxidant peptides from protein hydrolysate of Polygonatum cyrtonema Hua

Research on Polygonatum cyrtonema Hua has focused extensively on its main active components, yet antioxidant peptides remained less explored. This study optimized the preparation process of antioxidant peptides from P. cyrtonema via protein hydrolysis using response surface methodology. The peptide mixture was separated into four fractions using ultrafiltration and G-25 gel chromatography, based on antioxidant capacity. Notably, the F2 exhibited significantly higher Fe 3 ⁺ reducing power (17.17%) and ABTS· radical scavenging rate (30.1%) compared to other fractions at the same concentration. Characterization by Nano-LC-Q Exactive Plus quadrupole Orbitrap MS revealed that F2 contained 11,704 peptides, markedly more than the endogenous (2,454) and crude protein peptides (2,334). Bioinformatics and molecular docking identified three peptides—QFLPF, FVPF, and FPNLF—as having the highest antioxidant potential. These peptides increased cell viability in oxidative damage-induced HepG2 cells by 6.39%, 14.51%, and 9.98%, respectively, compared to the model group. This study lays the groundwork for future mechanistic investigations into the antioxidant peptides of P. cyrtonema.