Natural Polysaccharides with Immunomodulatory Activities.

Natural polysaccharide is a kind of natural macromolecular which can be extracted from plants, fungi, algae, animals, and bacteria. The monosaccharide compositions and glucosidic bonds of polysaccharides from different origins vary substantially. Natural polysaccharides have been shown to possess complex, important and multifaceted biological activities including antitumor, anticoagulant, antioxidative, antiviral, immunomodulatory, antihyperlipidemic and antihepatotoxic activities. Their properties are mainly due to their structural characteristics. It is necessary to develop polysaccharide immunomodulators with potential for preventive or therapeutic action. The present paper summarizes the structural features, immunostimulatory activity and the immunomodulatory mechanisms of natural polysaccharides. In particular, it also provides an overview of representative natural polysaccharide immunomodulators.