Screening and Functional Validation of Walnut-Derived Bioactive Peptides for Relieving Constipation

Peptide identification, molecular docking, and a zebrafish model of constipation were used to screen for peptides with laxative activity from an enzymatic hydrolysate of walnut meal. The most promising peptide, FGGDSTHPFN (FN-10), was further evaluated in a mouse model of constipation, and its physicochemical stability was characterized. The results revealed that 10 bioactive peptides with potential laxative effects were obtained, with FN-10 being the most effective among them. After administering FN-10 to constipated mice, we found that compared with the model group, the time to first black stool excretion of mice was significantly shortened by (46.93 ± 3.40)% and (34.65 ± 6.05)% (P < 0.05) in the low-dose (5 mg/kg m_b) and high-dose (30 mg/kg m_b) FN-10 groups, respectively. The number of fecal pellets at 5 h increased significantly by (102.78 ± 14.09)% and (43.98 ± 11.16)% (P < 0.05), respectively. The wet mass of feces increased significantly by (105.89 ± 14.23)% and (42.39 ± 15.12)% (P < 0.05), respectively, and the dry mass by (149.03 ± 23.00)% and (55.41 ± 17.22)% (P < 0.05), respectively. Additionally, FN-10 exhibited excellent physicochemical stability. Walnut peptide FN-10 is a natural bioactive peptide with laxative effects. This study provides a theoretical foundation for developing functional peptide products to alleviate constipation.