Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by recurrent gastrointestinal inflammation caused by abnormal immune response, and patients usually have intestinal flora imbalance. At present, the pathogenesis of UC is not well understood, and it appears that there is chronic activation of the immune and inflammatory cascade in genetically susceptible individuals. Some food supplements such as specific peptides and probiotics have been investigated and shown the potential for the treatment of UC. The purpose of this study is to investigate the therapeutic effect and potential mechanism of tetrapeptide from maize (TPM) and probiotic treatment on dextran sulfate sodium (DSS)-induced UC in C57BL/6J mice. Our results indicated that the therapeutic effects of TPM and probiotics are positively associated with a reduction in pro-inflammatory cytokine levels and restoration of the gut microbiota. Treatment with TPM or probiotics effectively alleviated the adverse effects of UC, including weight loss, shortened colon length, and colon and kidney tissue damage in mice. Additionally, both TPM and probiotics significantly reduced pro-inflammatory cytokine levels and oxidative stress in UC mice, and the effect was more pronounced when both were used together. Moreover, co-treatment with TPM and probiotics increased the diversity of gut microbes in UC mice, reduced the ratio of Firmicutes to Bacteroidetes (F/B) and increased the abundance of bacterial species, including Muribaculaceae, Alistipes, Ligilactobacillus and Lactobacillus, and has been shown to be beneficial for a variety of pathological conditions.

Recent studies have indicated that protein hydrolysates have broad biological effects. In the current study we describe a novel antioxidative peptide, FDPAL, from soybean protein isolate (SPI). The aim of this study was to purify and characterize an antioxidative peptide from SPI and determine its antioxidative mechanism. LC–MS/MS was used to isolate and identify the peptide from SPI. The sequence of the peptide was determined to be Phe-Asp-Pro-Ala-Leu (FDPAL, 561 Da). FDPAL can cause significant enhancement of resistance to oxidative stress both in cells as well as simple organisms. In Caenorhabditis elegans (C. elegans), FDPAL can up-regulate the expression of certain genes associated with resistance. The antioxidant activity of this peptide can be attributed to the presence of a specific amino acid sequence. Results from our work suggest that FDPAL can facilitate potential applications of proteins carrying this sequence in the nutraceutical, bioactive material and clinical medicine areas, as well as in cosmetics and health care products.

Food-derived bioactive peptides may have various physiological modulatory and regulatory functions and are now being studied extensively. Recently, the novel dipeptide Tyr-Ala was isolated from hydrolyzed maize protein. Tyr-Ala significantly prolonged the lifespan of wild-type Caenorhabditis elegans and extended the nematode healthspan and lifespan during heat/oxidative stress. Compared with its constituent amino acids, Tyr-Ala was more efficient in enhancing stress resistance. Further studies demonstrated that the significant longevity-extending effects of Tyr-Ala on Caenorhabditis elegans were attributed to its in vitro and in vivo free radical-scavenging effects, in addition to its ability to up-regulate stress resistance-related proteins, such as SOD (Superoxide Dismutase)-3 and HSP (Heat Shock Protein)-16.2. Real-time PCR results showed that the up-regulation of aging-associated genes, such as daf-16, sod-3, hsp-16.2 and skn-1, also contributed to the stress-resistance effect of Tyr-Ala. These results indicate that the novel dipeptide Tyr-Ala can protect against external stress and thus extend the lifespan and healthspan of Caenorhabditis elegans. Thereby, Tyr-Ala could be used as a potential medicine in anti-aging research.