Stability and Separation of Peptides from Seabuckthorn Seed Protein

In this study, peptides with inhibitory activity against porcine pancreatic lipase (PPL) from the alcalase hydrolysate of seabuckthorn seed meal protein were purified by ultrafiltration and macroporous resin separation, and their structures were investigated by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and molecular docking. The peptides had good thermal and pH stability. The PPL inhibitory activity was significantly improved by adding appropriate amounts of Na⁺ and Mg²⁺ but not influenced by short-term exposure to the air. A total of 31 peptides were identified by UPLC/MS-MS, and six peptides were selected by molecular docking, whose contents in the ultrafiltration fraction with molecular mass less than 3 kDa were as follows: VR (2.90%), FR (7.40%), RDR (1.10%), APYR (1.50%), NLLHR (1.40%) and EEAASLR (1.10%), respectively. The half-maximal inhibitory concentration (IC₅₀) values of VR, FR, RDR, APYR, NLLHR and EEAASLR prepared by solid phase synthesis were 371.07, 243.07, 250.50, 350.41, 220.70, and 510.55 μg/mL, respectively. The results of molecular docking showed that each of these peptides could combine with PPL by hydrogen bonding and π-π stacking interactions. Pearson correlation analysis showed that there was a positive correlation between molecular binding energy and the PPL inhibitory activity of the peptides from seabuckthorn seed protein (R² = 0.865, P < 0.05).