*2.8. Arctium lappa L. Polysaccharides*

*Arctium lappa* L. is one of the well-studied traditional medicines. The polysaccharide (ALP-1) isolated from *Arctium lappa* L. has the molecular weight of 5.12 kDa and is constituted of a (2→1)-β-d-fructofuranose backbone linked to a terminal of (2→1)-α-dglucopyranose at the non-reducing end and a (2→6)-β-d-fructofuranose branching. The anti-inflammatory impression of this alkaline extraction polysaccharide is thought to relate to its specific structure feature the (2→1)-linked type in fructan [47]. ALP-1 caused a higher relative abundance of Lactobacillaceae, Lachnospiraceae, as well as Ruminococcaceae, and a lower relative abundance of Bacteroides plus *Staphylococcus* in DSS-induced male ICR mice. It also led to a remarkable decline of pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, and improved levels of anti-inflammatory cytokines including IL-10 and immunoglobulin A (Ig A) in DSS-induced male ICR mice [48]. The pathogenic microorganisms are easier to be phagocytosed through phagocytic cells [49]. Similar effects were noted in another study conducted by Zhang and his coworkers where the same inflammatory cytokine results were observed when treating with ALP-1 in lipopolysaccharide (LPS)-induced RAW264.7 macrophage [50].

An alkali-soluble polysaccharide (ASPP) has proved to have a stronger anti-inflammatory and immunomodulatory effect [47,51]. Female ICR mice were administrated with ASPP 400 mg/kg body weight for 28 days. They displayed a higher abundance of probiotics such as *Firmicutes, Alistipes, Odoribacter, Lachnospiraceae,* as well as *Lactobacillus* in mice [52]. *Lactobacillus* not only has a reverse relationship with IL-1β but also prevents epithelial barrier disruptions by blocking TNF-α [53]. There is also an increment in the *Firmicutes/Bacteroides* ratio, which has a positive connection with a protective effect on IBD patients [54]. Except for elevating this ratio in the colon, ASPP simultaneously decreases the level of the harmful bacteria *Proteobacteria,* which boosts the excessive pro-inflammatory cytokines expression [55]. Otherwise, ASPP inhibits the expression of pro-inflammatory cytokines including IL-6, IL-1β, TNF-α, and IL-10 and decreases the overproduction of NO through down-regulating iNOS expression [56]. As one of the pro-inflammatory molecules, NO can stimulate the immune system [57] and is mediated by NF-κB and MAPKs pathways [58].

#### *2.9. Morinda citrifolia L. Polysaccharides*

*Morinda citrifolia* (Noni) has been utilized as medicine for a hundred years. Polysaccharides extracted from noni fruit (NFP) have been shown to exert numerous benefits such as being anti-diabetic, anti-inflammatory, anti-oxidant, and anti-cancer [59]. NFP is comprised of galacturonic acid, rhamnogalacturonan-I, arabinogalactan, and arabinan with a molecular weight of nearly 456 kDa. NFP could improve the tight junction protein production, including ZO-1 and occludins, and thus enhance the gut barrier integrity and decrease the possibility of endotoxemia in DSS-induced IBD mice [60].

### *2.10. Astragalus membranaceus Polysaccharides*

*Astragalus membranaceus* has been used for curing numerous conditions such as wounds, diabetes, leukemia, eye disease, and nephritis for several centuries [61]. Recent studies have proved that the *Astragalus* polysaccharides (APS) could exert immunomodulation and anti-oxidant effects. In DSS-induced male C57BL/6 mice, APS was administrated 200 mg/kg/day for the first 3 days. It promoted the colitis-related clinical indices, and noticeably, when compared with the DSS-induced colitis group, a histopathology assessment revealed that all of the ulcerations and mucosal, edema, and neutrophil infiltration in the epithelium of intestine were significantly reduced. APS also down-regulated production of MPO and pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6 as well as the expression of NF-κB in DSS-induced mice. Therefore, APS could relieve symptoms of colitis through modulating the NF-κB signaling pathway [62].

#### *2.11. Dendrobium officinale Polysaccharides*

*Dendrobium officinale* has been used as a Chinese medicine for thousands of years. Previous studies have displayed that the polysaccharides from *Dendrobium officinale* (DOP) make a significant contribution against inflammation and immunity modulating [63]. Recently, based on the specific endo-β-1,4-mannanase linear structure of DOP, Zhang et al. have separated the core domain of Dendrobium officinale polysaccharides (EDOP) after enzymatic. It consists of glucose and mannose with the molar ratio of 1.00:4.76 and is composed of (1→4)-β-d-Glcp and (1→4)-β-d-Manp with attached 2-O-acetylated groups [64]. The effects of EDOP on colitis were evaluated in DSS-induced colitis male Balb/c mice. Both DOP and EDOP could reduce the overexpression of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α together with their mRNA expression levels simultaneously, which could moderate the IBD to some extent. DOP and EDOP treatment increased the abundance of *Bacteroides, Lactobacillus,* plus *Ruminococcaceae*, and down-regulated the level of *Proteobacteria* and *Akkermansia* in the meantime. *Ruminococcaceae* is one of the common probiotics that could promote the degradation of complex polysaccharides followed by the increased production of SCFAs [65]. *Akkermansia* improves pro-inflammatory cytokine manufacturing and diminishes the SCFAs expression, as a result of a positive relationship with IBD [66]. DOP and EDOP also restored the mRNA expression level of GPR41/43, which reactivated the metabolism of SCFAs in the gut. These studies might explain that DOP and EDOP treatment recovered the level of acetic acid in the colon, thus promoting SCFA production in the gut. DOP can ameliorate IBD through exhibiting depression of NLRP3 inflammasome and β-arrestin1, following by subsequently regulating the expression of TLR-2,4,6,9 [67].
