Preparation and characterization of novel antioxidant peptides from protein hydrolysate of Ophiocordyceps gracilis

Abstract

Ophiocordyceps gracilis is a type of fungus commonly utilized in both health food and Chinese medicine. Herein, we prepared antioxidant hydrolysate from O. gracilis, and isolated and purified the prepared hydrolysate to obtain O. gracilis peptides-4–3–1 (OGP-4–3–1) grade with the highest scavenging activity on DPPH, ABTS and hydroxyl radicals. Three new peptides with high antioxidant capacity were identified as LFNHF, PLDRHPF and YPFLRPL, respectively. The three peptides can reduce the proportion of senescent cells conveying positive expression of senescence-associated-β-galactosidase (SA-β-Gal) and increase survival pace of H₂O₂-induced human hepatocellular carcinomas (HepG2 cells), and the protective effects on cellular against senescence might be related to their increase in the activities of antioxidant enzymes, as well as the decrease in the concentration of malondialdehyde (MDA) and reactive oxygen species (ROS). The molecular docking results indicated that they could form durable hydrophobic and hydrogen bonds with critical amino acid residues of the Kelch-like ECH-associated protein 1 (Keap1), which could potentially modulate pathway of nuclear factor erythroid 2-related factor 2 (Nrf2) in conjunction with Keap1. In conclusion, the current research offers a theoretical foundation for the further development of the anti-aging effect of OGP, which has a broad application prospect in the fields of functional food and cosmetics.