Marine organisms are rich sources of polysaccharides. Chitosan is a linear, positive-charged, alkaline polysaccharide repeating by glucosamine and N-acetylglucosamine (Fig. 3) [28,29], derived from the shells of shrimps and crustacean or the cell walls of fungi [30,31]. Marine algae products have been applied in traditional Chinese herbal medicine for a long time [11], and contain a variety of polysaccharides, including carrageenan, fucoidan, and alginate. Carrageenans are sulphated linear polysaccharides composed of repeating disaccharide units with alternating 3-linked β-d-galactopyranose (G-units) and 4-linked α-galactopyranose (D-units) or 3,6-anhydro-α- galactopyranose (AnGal-units) [[32], [33], [34]], which are extracted from certain red algae containing 15–40% ester sulfate with an average molecular weight above 100 kDa [35,36]. The three commercial most important and widely distributed carrageenans are iota (ι-, G4S-DA2S), kappa (κ-, G4S-DA) and lambda (λ-, G2S-D2S, 6S)-carrageenan (Fig. 3) [37]. Fucoidan is a fucose-enriched and sulfated polysaccharide extracted from brown algae [11,38], which is composed of L-fucose, sulfate groups and small proportions of D-xylose, D-mannose, D-galactose, and D-glucuronic acid in different sources of brown algae (Fig. 3) [[38], [39], [40]]. Alginate, an acidic and linear polysaccharide extracted from brown algae, is consisted of alternating β-D-mannuronic acid (M) and α- L-guluronic acid (G) residues [41]. Polyguluronate sulfate (PGS) (Fig. 3) is a low molecular weight sulfated brown algae polysaccharide obtained by chemical sulfation of polyguluronate (PG) with about 1.5 sulfate per sugar residue [42,43].