Structural features of a polysaccharide from Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao

Abstract

A polysaccharide Astragalus polysaccharide (APS) was obtained from the boiling water extract of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao. The results of gas chromatography (GC) indicated that APS consisted of l-rhamnose (l-Rha), d-xylose (d-Xyl), d-glucose (d-Glc), and d-galactose (d-Gal) in the molar ratio of 1:4:5:1.5. Its molecular weight was determined to be 3.01 × 10⁵ by high-performance gel filtration chromatography. The results of ¹H NMR and ¹³C NMR spectral analysis indicated that APS had a linear backbone mainly consisting of 1,3-linked β-d-Gal residues with insertion of β-Glc, 1,6-linked α-Gal, 1,5-linked β-Xyl, 1,4-linked β-Gal, β-d-Gal, 1,2-linked α-Rha, 1,2,4-linked α-Rha residues. HSQC spectrum indicated that C-2 and C-6 may link with H.

Keywords:

• Astragali membranaceus
• polysaccharide
• structure

Acknowledgements

This work was financially supported by the Key National Natural Science Foundation of China (81130069); selected program of Personnel Department for Oversea Scholar (2009–2011); the Chinese National S&T Special Project on Major New Drug Innovation (2011ZX09307-002-01); the key technologies of the quality standards and the safety of health food, ‘863 Program’ (2010AA023006).