A Review of Pharmacological Activities of Mushroom Polysaccharides

In the last few decades, mushrooms have increasingly been used as a source of therapeutic agents or health food supplements. In particular, polysaccharides or polysaccharide-protein complexes derived from mushrooms have received much attention in biomedical research. These bioactive biopolymers are mainly present as glucans with different types of glycosidic linkages, such as (1→3), (1→6)-β-glucans and (1→3)-α-gtucans, while others mostly bind to protein residues as polysaccharide-protein complexes. One of the most promising activities of these polysaccharides is their immunomodulation and anticancer effect. Three antitumor polysaccharides, namely lentinan, schizophyllan, and protein-bound polysaccharide (or polysaccharopeptide), have been isolated from Lentinus edodes (Berk.) Sing., Schizophyllum commune (Fr.: Fr.), and Coriolus versicolor (L.: Fr.) Quel. [= Trametes versicolor (L.: Fr.) Lloyd], respectively, and have become large nutraceutical and pharmaceutical market items, particularly in Japan. The mechanism of their antitumor actions is still not completely understood. But it is widely accepted that antitumor polysaccharides from higher fungi enhance various immune responses in vivo and in vitro, and act as biological response modifiers. Potentiation of the host defense system may result in the activation of many kinds of immune cells that are vitally important for the maintenance of homeostasis. In addition to immunomodulation and antitumor activity, there are new potential applications of mushroom polysaccharides or polysaccharide-protein complexes for pharmaceutical and functional food development. These polysaccharides have been shown to have various potent pharmacological properties, such as antioxidant, free radical scavenging, antiviral, hepatoprotective, antifibrotic, antiinflammatory, antidiabetes, and hypocholesterolemic activities.