Immunomodulatory activities of five clinically used Chinese herbal polysaccharides

Polysaccharide is a natural macromolecular compound with complex, important and multifaceted biological activities. Some of polysaccharides have been marketed in China as drugs or healthy products. More studies confirm that the active ingredient of many traditional Chinese medicine exist in the form of polysaccharides. They play a role in disease therapy by activating immune cells and the complement system; regulating the cytokines expression; promoting the production of antibodies; inhibiting tumor cell proliferation and inducing tumor cell apoptosis; inhibiting virus entering cells and replication; increasing activity of antioxidant enzyme; scavenging free radicals; and inhibiting lipid peroxidation. In this review, we focus on the immunomodulatory effects and its possible mechanism of polysaccharides from Chinese herbal polysaccharides products, including Lentinan, Astragalus polysaccharide, Polyporus polysaccharide and Achyranthes bidentata polysaccharide. The immunomodulatory activities of polysaccharides were categorized in the paper into general immunoregulatory activity, anti-tumor, anti-infections, antiinflammatory, anti-oxidative, anti-mutagenic and radioprotective, anti-complementary, anti-adhesive, and anti-allergy since all the activities are related to modulate immune responses by the polysaccharides. Also the challenges in the research of polysaccharides will be discussed.