Elucidation of the structure of a bioactive hydrophilic polysaccharide from Cordyceps sinensis by methylation analysis and NMR spectroscopy

• Published in: Carbohydrate polymers 2011-03, Vol.84 (3), p.894-899
• Main Authors: Nie, Shao-Ping, Cui, Steve W., Phillips, Aled O., Xie, Ming-Yong, Phillips, Glyn O., Al-Assaf, Saphwan, Zhang, Xiao-Liang
• Format: Article
• Language: English
• Subjects: Applied sciences; bioactive properties; Biological and medical sciences; Cordyceps sinensis; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; galactose; glucose; Hydrophilic polysaccharide; hydrophilicity; mannose; methylation; Methylation analysis; Microbiology; Morphology, structure, chemical composition; Mycology; Natural polymers; NMR; nuclear magnetic resonance spectroscopy; Ophiocordyceps sinensis; Physicochemistry of polymers; polysaccharides; Starch and polysaccharides; Structure
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2010.12.033

The structure of a bioactive hydrophilic polysaccharide fraction from Cordyceps sinensis (CBHP) was studied using methylation analysis and 2D NMR spectroscopy. Monosaccharide composition analysis revealed that it consists mainly of glucose (95.19%) with trace amounts of mannose (0.91%) and galactose (0.61%). The results of methylation analysis indicated that α-1,4 linked Glc p is the main linkage type (65.7%), followed by t-Glc p (20.7%), 1,2,3,6-Glc p (4.1%), 1,2,4,6-Glc p (3.0%), 1,3,6-Glc p (2.0%), 1,4,6-Glc p (1.6%), and 1,2-Man p (1.9%) and 1,3-Gal p (1.0%). Based on 1D and 2D NMR analysis, a preliminary structure is proposed: The backbone is composed of Glc p joined by 1 → 4 linkages and 1 → 3 linkages; the branching points are located at O-2 or O-6 of Glc p with α- terminal- d-Glc p as side chain. The trace amounts of 1,2-Man p and 1, 3-Gal p linkages are probably located randomly in the side chains. A schematic structure is proposed as following: [Display omitted]