Isolation, Purification and Structural Characterization of a Polysaccharide from <i>Rheum Palmatum</i> L.

Rhubarb is a widely used Traditional Chinese Medicine in treating various diseases for thousands of years, and polysaccharide is one of the bioactive constituents in this herb. However, study of the polysaccharide is very limited, especially structural characterization. In the present study, a polysaccharide from Rheum palmatum L. (PR) was isolated and puried. Based on UV, IR, GC, GC-MS, 1H NMR and 13C NMR analyses, the structure of PR was characterized. Its molecular weight was measured to be 1.21 × 10⁴ Da. The results of PR structural analysis showed that four 1→4 galactose were linked with one 1→ 3, 6 galactose and one 1→6 glucose, and each repeating unit had a branched chain consisting of a α-1→ xylose, which was linked with the C-6 of galactose backbone chain.