Kumquat pomace removal of free polyphenol alleviates induced acute enteritis and restores gut microbiota in dextran sodium sulphate-treated mice

Kumquat pomace non-extractable polyphenols (KNEP), which contains celobiotics and has anti-inflammatory and antioxidant effects, are one of the main components in kumquats. We aimed to determine the preventive and inhibitory effects of KNEP on dextran sodium sulphate (DSS)-induced inflammatory bowel disease (IBD). The disease activity index (DAI) score, H&E staining, high-throughput sequencing technology, quantitative analysis, ELISA, and western blotting were used to explore the effect of KNEP in an IBD mouse model. The DAI score and H&E staining results showed that compared with the DSS treatment group, the DAI and pathological status of IBD in the DSS + 3% KNEP (low-dose) and DSS + 6% KNEP (high-dose) intervention groups were significantly improved. High-throughput sequencing showed that the composition of the intestinal flora was restored under KNEP, and the abundance of pathogenic bacteria decreased and that of beneficial bacteria increased. Quantitative analysis of short-chain fatty acids (SCFAs) showed that the SCFAs content in the cecum of IBD mice increased in a dose-dependent manner. ELISA results showed that KNEP at different doses could inhibit the expression of TNF-α, IL-1β, IFN-γ, and other inflammatory factors, and that 6% KNEP had the most potent inhibitory effect. Western blotting results showed that KNEP inhibited the expression of TLR4, NF-κB, and NLRP3 in the colon of mice with DSS-induced colitis in a dose-dependent manner. These results indicate that KNEP can significantly improve DSS-induced acute colitis in mice, and the higher the KNEP content, the more pronounced the improvement in IBD.