Isolation and characterization of a mannoglucan from edible Cordyceps sinensis mycelium

Cordyceps sinensis is a well known tonic food or invigorant with broad-spectrum medicinal properties that is widely used in the People’s Republic of China. A neutral mannoglucan 1 with a molar mass of ∼7.7 × 103 Da was obtained from the 0.05 M acetate buffer extract of C. sinensis mycelium. It had image +126 (c 0.2, H2O) and consisted of Man and Glc units in the molar ratio of 1:9. A combination of chemical analysis and NMR and IR spectroscopy together with digestion with α-d-amylase showed 1 to have a α-d-glucan backbone with (1→4)- and (1→3)-linkages, and the side chains of α-d-(1→6)-Manp were attached to the backbone via O-6 of α-(1→3)-Glcp residues. Compound 1 showed weak cytotoxicity activity against SPC-I (IC50 = 63 μg/mL) cancer line, and no obvious cytotoxicity activities against BCAP37 (IC50 > 100 μg/mL) and SW480 (IC50 > 100 μg/mL) cancer lines.