Structural characterization and immunostimulatory activity of a glucan from natural Cordyceps sinensis

A water-soluble polysaccharide , named NCSP-50, was obtained from natural Cordyceps sinensis by hot water extraction and ethanol fractionation precipitation. It was eluted as a single symmetrical peak and had an average molecular weight of 9.76 × 10 5 Da. The structure was determined by monosaccharide composition, methylation analysis, 1D/2D NMR spectroscopy, and enzymatic hydrolysis and characterization of the oligosaccharides by MALDI-TOF mass spectrometry. The repeating unit of this polysaccharide was proposed as follows: This glucan showed potent immunostimulatory activity on the basis of its significant abilities to promote macrophage proliferation, enhance NO production, as well as and cytokines (IL-1β and TNF-α) secretion. • A homogenous polysaccharide (NCSP-50) from natural Cordyceps sinensis was isolated and purified. • NCSP-50 is a 4-linked α-glucan substituted by α-glucose units attached to C-6. • The glucan showed a significant immunostimulatory effect on macrophages.