Structural characterization of immunostimulating polysaccharide from cultured mycelia of Cordyceps militaris

The water soluble crude polysaccharide obtained from cultured mycelia of Cordyceps militaris (CPM) by hot water extraction followed by ethanol precipitation was fractionated by DEAE cellulose and Sepharose CL-6B column chromatography. This fractionation process resulted in four polysaccharide fractions that were termed CPMN Fr I, CPMN Fr II, CPMN Fr III, and CPMN Fr IV. Of these fractions, CPMN Fr III was able to upregulate the functional events mediated by activated macrophages, such as production of nitric oxide (NO) and expression of cytokines (IL-1β and TNF-α). Its structural characteristics were investigated by a combination of chemical and instrumental analyses, including methylation, reductive cleavage, acetylation, Fourier transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC–MS). Results indicate that CPMN Fr III was a high molecular mass polysaccharide with a random coil conformation of the β-1,4-branched-β-1,6-galactoglucomannan.