Preparation and antioxidant activity of hydrolysates from Litsea cubeba oil processing residuals: fluorescence chromatography and molecular dynamics simulation

The protein of oilseed crops can be hydrolyzed into peptides by enzymatic hydrolysis. In our investigation, 9 antioxidant peptides from the protein hydrolysate fraction of Litsea cubeba by RP-HPLC and identified as AN, VEQ, RV, VQ, VHDVSF, FQI, EAALA, VVGGG, and LA, respectively. The in vitro antioxidant assay results showed VHDVSF had the most potent antioxidant activity. Additionally, VHDVSF modulated the kelch-like ECH-associated protein l (Keap1)/ nuclear factor erythroid 2-like 2 (Nrf2) pathway to protect against hepatocellular oxidative stress damage. The ultraviolet-visible absorption and fluorescence spectra analysis indicated that VHDVSF might bind to the recombinant Keap1 protein through hydrogen bond formation and hydrophobic interactions. The results of molecular dynamics simulations (MDS) indicate that the binding to Keap1 protein is spontaneous and driven mainly by electrostatic interaction forces and van der Waals forces, which provided theoretical essential support for exploring VHDVSF as an antioxidant.