Adzuki Bean Peptide Prevents DSS-Induced Colitis by Modulating the Gut Microbiota

Background: The incidence of ulcerative colitis (UC) continues to rise, and food-derived bioactive peptides have attracted increasing attention as potential nutritional interventions for intestinal inflammation. This study investigated the preventive effects of the adzuki bean-derived peptide IFNNDPNNHP (IP10 peptide) on dextran sulfate sodium (DSS)-induced acute colitis in mice and explored the involvement of the gut microbiota. Methods: Mice received prophylactic IP10 peptide at 100 or 200 mg·kg−1. Colitis severity was assessed based on body weight, disease activity index, colon length, histopathology, and inflammatory cytokine levels. Gut microbiota composition was analyzed by 16S rRNA gene sequencing, and fecal short-chain fatty acid (SCFA) levels were quantified. Antibiotic-mediated microbiota depletion and fecal microbiota transplantation (FMT) were used to further evaluate the role of the gut microbiota. Results: Prophylactic IP10 peptide administration attenuated DSS-induced colitis, with the 200 mg·kg−1 dose more effectively attenuating body weight loss and colon shortening, reducing disease activity index scores, and modulating inflammatory cytokine levels. IP10 peptide increased microbial richness and diversity, decreased the relative abundance of Escherichia-Shigella, and increased the relative abundances of SCFA-associated taxa, including norank_f__Muribaculaceae and Lachnospiraceae_NK4A136_group. It also increased fecal SCFA levels, particularly acetate and butyrate; the high dose additionally restored propionate and valerate. When the gut microbiota was depleted using antibiotics, the protective effects of the IP10 peptide were no longer detectable, whereas FMT using fecal microbiota from donors receiving the high dose of IP10 peptide attenuated colitis and increased fecal SCFA levels in recipient mice. Conclusions: IP10 peptide alleviates DSS-induced acute colitis, and this effect may be partly associated with alterations in the gut microbiota, including the enrichment of SCFA-associated taxa and increased fecal SCFA levels. These findings support its potential as a functional food ingredient for intestinal health.