Preparation and Characterization of Rice Bran Protein Hydrolysates Enhanced via Alcalase and Lactiplantibacillus plantarum 13110 Co-Treatment: Antioxidant Properties and Ameliorative Effects on Ulcerative Colitis in Mice

Background: Ulcerative colitis, a chronic inflammatory disorder of the intestine, represents a major health concern worldwide. This study aimed to explore the in vivo efficacy of rice bran protein hydrolysates in mitigating UC. Methods: Rice bran protein hydrolysates with enhanced antioxidant activity were prepared via co-treatment with Alcalase and Lactiplantibacillus plantarum 13110. Results: Compared with hydrolysates obtained using Alcalase in isolation (RHP), the co-treated rice bran (CRB) protein hydrolysates exhibited significantly higher antioxidant capacity. Structural characterization revealed marked alterations in molecular weight distribution, amino acid composition, and RHP spectral features, based on Fourier transform infrared spectroscopy, during fermentation with L. plantarum 13110. The 500 mg/kg·bw CRB intervention effectively attenuated oxidative stress and inflammatory responses in dextran sulfate sodium (DSS)-induced colitic mice, as evidenced by significantly reduced colonic levels (p < 0.05) of pro-inflammatory mediators (TNF-α, IL-1β, IL-6, and LPS), decreased serum concentrations of fatty acid-binding protein 2 (FABP2), diamine oxidase (DAO), and D-lactic acid (D-LA), and increased colonic IL-10 content (p < 0.05). These changes were associated with ulcerative colitis amelioration and improved intestinal barrier function. Conclusions: Thus, CRB exhibits promising prophylactic effects against ulcerative colitis, suggesting its potential for therapeutic application.