*2.1. Polysaccharides from Hericium Erinaceus*

A purified polysaccharide (EP-1) isolated from *Hericium Erinaceus* has been studied for its anti-gastric/colitis ulcer activity [11]. The molecular weight of EP-1 is around 3.1 kDa and the structure is constituted of glucose, mannose, and galactose, whose backbone is α-d-Glc(1→3) and β-d-Glc(1→3) and both of them are branches with C-4 position [13].

Recently, EP-1 has been confirmed to relieve the symptoms of ulcerative colitis induced by acetic acid [14]. As it enters the lower gastrointestinal tract, the polysaccharide would be fermented by the gut microbiota to form SCFAs. The carbon from different polysaccharides gets used as the unique energy source for particular microbes in intestine [15]. Therefore, the polysaccharides could change the composition of the gut microbiota, which is companied with changes of the SCFAs. EP-1 changes the bacteria community through recovering the levels of *Firmicutes, Bacteroidetes, Proteobacteria*, and *Actinobacteria* with the increase of SCFAs, including ethanoic acid and butanoic acid, in the colon. SCFAs including acetate, propionate, and butyrate are the last degraded product metabolized from polysaccharides by the gut microbiota [16], which influence the diversity of intestinal microbiota, and contribute vitally to immune response regulation in the gastrointestinal system [17].

Another polysaccharide was extracted from *Hericium erinaceus*, whose molecular weight is 86.67 kDa. It was also reported to down-regulate the expression of IL-6, IL-1β, TNF-α, and cyclooxygenase-2 (COX-2); induce iNOS; and decrease the expression of related mRNA in dextran sulfate sodium (DSS)-induced mice [18]. iNOS belongs to the systems of reactive oxygen/nitrogen species (ROS/RNS) generation that stimulate oxidative stress. Oxidative stress is tightly connected with the production of inflammatory cytokines and inflammatory cell penetration [19]. As the polysaccharides reduce the expression of iNOS, there is the amelioration of oxidative stress. Otherwise, iNOS stimulates the manufacture of

the NO and promotes the expression of COX-2; the latter could catalyze the prostaglandin production finally induced the inflammation responses. All of these implementations depend upon the NF-κB signaling pathway [20].

#### *2.2. Sarcodon aspratus Polysaccharides*

The water-soluble polysaccharide (HCP) extracted from *Sarcodon aspratus* with a molecular weight of 6.7 × 103 kDa was reported having immunomodulatory function in the intestine. HCP has a backbone structure of (1→6)-linked-α-d-glucopyranosyl residues. HCP facilitates the immunity function of macrophages cells through the TLR4-MAPK-NFκB signaling pathway, which enhances the phagocytic activity and promotes the expression of NO, iNOS. HCP works toward regulating the immunity in the intestine through moderating inflammatory cytokines secreted from immunity cells [21].
