Peptides from Dalian Stichopus japonicus: Antioxidant Activity and Melanogenesis Inhibition In Vitro Cell Models and...

This article aims to reveal the optimal peptide segment with antioxidant activity from Dalian Stichopus japonicus, investigate its anti-melanogenesis effect, and elucidate its mechanisms of action both in vitro and in vivo. The best antioxidant alcalase hydrolysates, identified by the previous screening of proteases, was isolated by ultrafiltration; it was found that the components with a molecular weight of ≤ 3 kDa exhibited the best activity. The chemical components were characterized using LC-MS/MS. Through molecular docking, GPIGF was identified as the peptide segment with the best antioxidant and melanogenesis-inhibitory activity. A search in the NCBI database revealed that GPIGF is a newly obtained natural oligopeptide. Further experiments with synthesized GPIGF in vitro showed that it effectively reduces cell apoptosis and damage, and inhibits the expression of melanin-related genes, including tyrosinase (TYR), and associated proteins TRP-1, TRP-2, and MITF. In vivo experiments with the zebrafish model demonstrated that GPIGF significantly inhibits AAPH-induced apoptosis in zebrafish larvae, reduces the production of ROS, and suppresses melanin generation on the skin surface without exhibiting embryotoxicity. This study provides a research foundation for the development of antioxidants from Dalian Stichopus japonicus, which could serve as natural whitening and anti-aging agents, supporting its integrated utilization and development.