Preparation and immunological activity of polysaccharides and their derivatives.

Polysaccharide is a kind of natural macromolecule polymer, which is widely existed in animals, plants and microorganisms, has a variety of biological activities, such as anti-tumor, anti-virus, anti-oxidation and immune regulation. Polysaccharides can affect macrophages, cells and other immune cells to improve the body's immune function, and have no toxic and side effects on normal cells, which make the polysaccharides receive widespread attention. In recent years, studies have shown that structural modification of polysaccharides can improve the immunological activity of polysaccharides. The common chemical modifications are sulfation, carboxymethylation, acetylation, phosphorylation, and so on. The chemical modification of polysaccharides and the immunomodulation of polysaccharides and polysaccharide derivatives were analyzed and discussed.