*2.12. Lycium barbarum Polysaccharides*

*Lycium barbarum* (Goji berry) has been utilized in medicine and diet for thousands of years. The major backbone of the polysaccharide isolated from *Lycium barbarum* (LBP) is comprised of (1→3)-β-d-galactopyranosyl, (1→6)-β-d-galactopyranosyl, and (1→4)-α-d-galactopyranosyluronic acid residues, and the molecular weight cover from 2.1–6.5 × 103 kDa [68]. The supplementation of LBP promoted growth of intestinal probiotics such as *Akkermansia, Lactobacillus,* and Prevotellaceae. It also significantly increased the expression level of TGF-β and IL-6 in serum and sIgA in colon tissues [69]. Furthermore, treatment with LBP ameliorated the colitis symptoms in DSS-induced colitis C57BL/6 mice, which includes alleviating the damage of mucus and reducing the neutrophil infiltration in colonic tissues [68]. LBP could inhibit the production of chemokine ligand 1 (CXCL1), and monocyte chemoattractant protein 1 (MCP-1), together with the down-regulation of COX-2 [70]. CXCL1 is one of the potential chemo-attractants that could trigger neutrophils recruitment and activation in inflammation [71]. MCP-1 can attract immunity cells including monocytes, macrophages, and lymphocytes [72]. Both of them play an essential role in the occurring of colitis. The results have suggested that LBP might alleviate the IBD symptoms by restoring the normal level in the gut and decreasing the neutrophil infiltration.

#### *2.13. Codonopsis pilosula Polysaccharides*

*Codonopssi pilosula* polysaccharides (CREP) were used as an effective medicine for ulcerative colitis. CREP is comprised of mannose, rhamnose, galacturonic acid, glucose, galactose, and arabinose at the molar ratio of 1.00:3.26:27.87:10.87:7.70:9.94. Tang et al. found that CREP could ameliorate colitis symptoms in the DSS-induced mice combined with APS. In addition to the administrative effect, APS decreases the expression of proinflammatory cytokines and supplies CREP in the treatment, causing down-regulation of TJs proteins including occludin, ZO-1, claudins, and MUC-2 [73].

Especially, administration of CREP in the DSS-induced mice leads to the up-regulation of IL-22. IL-22 is one of the cytokines that belongs to the IL-10 family and can protect the gastrointestinal tract in the colitis models. A previous study has confirmed that the blocking IL-22 pathway prolongs recovery in the DSS-induced colitis model. IL-22 makes a crucial protective contribution to intestine integrity. On the one hand, IL-22 could facilitate the goblet cells' secret mucins, which form the stabilized external barrier to sequester the direct interaction between epithelial cells and microorganisms [74]. On the other hand, it also could promote trauma healing through activating the STAT3 pathway in epithelial cells [75]. Therefore, CREP have potential effects to ameliorate IBD symptoms.

#### *2.14. The Polysaccharides from Purple Sweet Potato*

Purple sweet potato contains three polysaccharides consisting of water-soluble polysaccharide (WPSPP), dilute alkali-soluble polysaccharide, and concentrated alkali-soluble polysaccharide [76]. The backbone of the alkali-soluble polysaccharide (ASPP) obtained from purple sweet potato is composed of 1,4-linked Glcp with side chains attached to the O-6 position [77]. Sun et al. found that female ICR mice had higher levels of acetate and propionate when administrated with ASPP 400 mg/kg body-weight once a day for 30 days. ASPP inhibited the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α, and the anti-inflammatory property of ASPP was by up-regulating the level of SCFAs [78].

A purified polysaccharide (WPSPP-1) from purple sweet potato was constituted of 1,6-α-d-Glcp, 1,4-α-d-Glcp, 1,2-α-d-Manp, and 1,4,6-α-d-Glcp with β-d-Glcp on the branches, and exhibited a molecular weight of 10<sup>3</sup> kDa [79]. The administration of WPSPP-1 can promote SCFA production including acetate, propionate, and butyrate. It recovered inflammatory lesions through improving IL-10, SOD, and T-AOC levels and reducing IL-1β, TNF-α, IL-6 together with MDA levels. Meanwhile, it increased the ratio of Firmicutes/Bacteroides and decreased the proportion of Proteobacteria, exerting a beneficial effect on the colonic microbiota modulation [54].

#### *2.15. Others*

Polysaccharides (TFPS) from the flowers of *Camellia sinensis* L, which are comprised of two kinds of polysaccharides with a molecular weight of 4.4 kDa and 31 kDa [80] exhibit immunostimulant activity. TFPS have a probiotic-promoting effect which works through increasing the ratio of probiotics in IBD, which significantly changes the composition of the metabolite SCFAs. In IBD feces, the relative abundances of *Escherichia/Shigella, Enterococcus, Collinsella, Lactobacillus,* and *Bifidobacterium* were increased, while the relative abundances of *Enterobacter, Ptococcus, Bacteroides, Clostridium XlVa, Megasphaera, Roseburia, Granulicatella, Akkermansia* and *Fusobacterium* decreased [81].

The polysaccharides from *Ficus carica* (FCPS) were considered to be used in nutritional therapy due to their anti-oxidant and anti-inflammatory function. FCPS has a molecular weight of 98.9 kDa and is comprised of rhamnose, arabinose, glucose, galactose as well as galacturonic acid with ratios of 5.8:18.1:3.3:19.3:53.5. The administration of FCPS in DSS-treated mice could down-regulate the mRNA expression of IL-1β, TLR4, and iNOS; the high-dose FCPS essentially decreased the mRNA expression of TNF-α, IL-6, MCP1, and COX-2, which resulted in the inhibition of colon inflammatory response [82].

FCPS treatment could decrease the abundance of *Esherichia* and *Clostridium. Esherichia* always multiplies the danger of colitis and *Clostridium* is related to the production of SCFAs. The administration of FCPS can improve the level of *Prevotella, Bacteroides, Butyricicoccus*, and Coprococcus. All of them have been reported to be beneficial in preventing IBD through down-regulating the expression of SCFAs [83]. The effects of some natural polysaccharides on inflammatory bowel disease are shown in Table 1.




