Isolation, Structure and Cholesterol Esterase Inhibitory Activity of a Polysaccharide, PS-A, from Cordyceps sinensis

A heteropolysaccharide possessing strong inhibitory activity against cholesterol esterase, namely PS-A, was isolated from water extracts of Cordyceps sinensis by activity-guided fractionation. The molecular weight of PS-A was estimated as 4.6x10(5) Da. Compositional analysis revealed the presence of D-glucose, D-galactose, and D-mannose at a molar ratio of 2:1:1. The (1)H and (13)C nuclear magnetic resonance spectra, correlation spectroscopy, nuclear Overhauser effect spectroscopy, and heteronuclear multiple bond correlations experiment established the structure of PS-A as follows: -> 3)alpha-D-glcp(1 -> 3)beta-D-glcp(1 -> 3)beta-D-glcp(1 -> [GRAPHICS] alpha-D-Manp Results of the in vitro enzyme assay showed strong inhibition of cholesterol esterase by PS-A, with an IC(50) value of 12.7 mu g/mL, suggesting the possibility of its usefulness as a potential agent for control of hypercholesterolemia.