Protective effects of six different pectic polysaccharides on DSS-induced IBD in mice

Administration of pectic polysaccharides is a therapeutic strategy in the management of gut inflammation. However, the knowledge about the effects of different dietary sources and structure are missing. This study explored the protective effects of six different pectic polysaccharides from Goji berry (G), dragon fruit (D), lemon (L), pomelo (P), potato (T) and raspberry (R) in dextran sulfate sodium (DSS)-induced colitis mice. D mainly contained rhamnogalacturonan (RG) backbone; L had high amount of arabinan sidechains; P was a high-esterified homogalacturonan (HG) pectic polysaccharide; the primary domain in T was galactan sidechains; R and G had the composition of arabinan: galactan: RG: HG = 19: 28: 15: 22 and 36: 17: 21: 14. Our results suggested that G and R were the most effective in alleviating colitis via alleviating tissue damage, promoting the index of immune organs, suppressing the production of TNF-α, IL-1β and IL-17, improving antioxidant status and promoting the total amount of SCFAs. Similarly, the administration of L alleviated colitis mainly by increasing the fermentation products without changes in the composition pattern of SCFAs. The secretion of IL-6 might be suppressed by pectic polysaccharides containing high amount of arabinan sidechains, while anti-inflammatory cytokines and intestinal barrier function tend to be regulated by pectic polysaccharides rich in galactan. In conclusion, pectic polysaccharide containing diversified structural domains (homogeneous proportion of HG, RG, arabinan, and galactan) might be the most effective in alleviating gut inflammation. This unprecedented report revealed the anti-inflammatory effects of different pectic polysaccharides, which was critical for the reasonable selection of dietary fiber to prevent gut inflammation.