Isolation and purification of a polysaccharide from the caterpillar medicinal mushroom Cordyceps militaris (Ascomycetes) fruit bodies and its immunomodulation of RAW 264.7 macrophages.

A novel polysaccharide (CP2-S) was purified from Cordyceps militaris fruit bodies by hot water extraction, ethanol precipitation, DEAE-Sepharose Fast Flow and Sephacryl S-400 high-resolution chromatography. The polysaccharide had a molecular weight of 5.938 × 10(6) g/mol and was mainly composed of glucose. CP2-S had carbohydrate content estimated to be 100% using the phenol-sulfuric acid method. Immunostimulating experiments in vitro indicated that CP2-S could stimulate nitric oxide production, phagocytosis, respiratory burst activity, and secretion of interleukin-1β and interleukin-2 of macrophages, suggesting that this water-soluble polysaccharide from the fruit body of C. militaris is a natural immunostimulating polysaccharide with potential for further application.