Cordyceps militaris, a typical Chinese traditional medicine, and its polysaccharide in functional food is very promising. The aim of this study was to clarify the structural characterization and biological activity of CP2-c2-s2 from C. militaris (CMP). High-performance gel permeation chromatography (HPGPC) and polyacrylamide gel electrophoresis (PAGE) analysis showed that CP2-c2-s2 was a homogeneous polysaccharide with an average molecular weight of 20 200 Da. The Fourier transform infrared spectroscopy (FTIR) and periodate oxidation analysis revealed that CP2-c2-s2 is a β-pyran polysaccharide, probably with 1→2, 1→4, and 1→6 glycosyl linkages. Micromorphologic observation showed different aggregates and networks from 5 μg mL−1 to 250 μg mL−1. CP2-c2-s2 significantly stimulated the proliferation of T and B lymphocytes, and obviously extended the average lifespan without adverse effects on fecundity, and delayed the age-related decrease in Caenorhabditis elegans. Overall, our results revealed significant immunomodulatory and anti-aging activities of CMP, which may provide useful information for CMP in functional foods.
