Structure and anti-tumor activity of a high-molecular-weight polysaccharide from cultured mycelium of Cordyceps gunnii

Cordyceps gunnii (berk.) Berk (C. Gunnii) is well known as a Chinese rare caterpillar fungus and has similar pharmacological activity with C. sinensis. In this work, a high-molecular-weight polysaccharide (CPS) was isolated and purified from the mycelia of C. gunnii. The total sugar content of CPS was amounted to 92.84%. The result of HPLC indicated that CPS was a homogeneous polysaccharide. The estimated average molecular weight of CPS was 3.72 × 106 Da. The specific rotation of CPS was recorded [α]D25=+134.2°. Its characteristic was determined by chemical analysis, gas chromatography, IR spectroscopy and NMR data. The results showed that CPS was mainly composed of glucose, and a small amount of rhamnose, arabinose, xylose, mannose and galactose with a molar ratio of Rha:Ara:Xyl:Man:Glu:Gal = 3.0:2.6:1.0:1.3:106.0:2.8. The main chain of CPS was majorly composed of α-(1 → 4) glucose. The tumor inhibition ratio on K562 cell by CPS was 56.65%.