Screening, stability, and in vitro hypolipidemic activity of pancreatic lipase inhibitory peptides from walnut dregs

Walnut dreg is a high-quality protein resource rich in a variety of bioactive peptides. However, the research on pancreatic lipase inhibitory peptides from walnuts is limited. In this study, different molecular-weight fractions of alkaline protein hydrolysate from walnut dreg were found to exhibit inhibitory activities against pancreatic lipase, with the < 1 kDa fraction exhibiting the most prominent activity, followed by the 1–3, 5–10, and 3–5 kDa fractions, showing IC₅₀ values of 12.22, 13.60, 17.23, and 37.65 mg/mL, respectively. Within the < 1 kDa fraction, five peptides (VIAFP, LVAFP, IAFP, LTYP, and LFDP) with the strongest binding ability (−10.03 kcal/mol to −11 kcal/mol) to pancreatic lipase were screened by molecular docking technique. Among them, LFDP (IC₅₀ = 6.931 mmol/L) exhibited the strongest pancreatic lipase inhibitory activity and reversible competitive pancreatic lipase inhibition. LFDP induced fluorescence bursts and structural changes in pancreatic lipase and exhibited strong biological activity even under high temperatures, strong acidic and alkaline conditions, exposure to metal ions, and gastrointestinal digestion conditions. In addition, LFDP significantly inhibited lipid accumulation in 3T3-L1 adipocytes. In conclusion, these results suggest that the peptide LFDP from walnut dregs is a potential pancreatic lipase inhibitor.