Characterization and comparison of polysaccharides from Achyranthes bidentata, Cyathula officinalis and Achyranthes aspera by saccharides mapping.

Although the roots of Achyranthes bidentata (AB), Cyathula officinalis (CO) and Achyranthes aspera (AA) are different drugs, they are always confused in clinical practice due to their similar chemical components and functions. As polysaccharides are abundant in these drugs, a systematic comparison of polysaccharides from AB, CO and AA is not only necessary to understand their similar but not identical functions, but also helpful for the quality control of them. In this study, polysaccharides from 22 batches of AB, CO and AA were compared with monosaccharide composition, molecular weight distribution and saccharide mapping. Polysaccharides of AB, CO and AA had similar monosaccharide compositions but their relative contents of fructose, glucuronic acid, galacturonic acid and glucose were significant different, and could be used as key markers to distinguish them. Results from molecular weight distribution and saccharide mapping showed polysaccharides from AB, CO and AA were mainly composed of fructans with β-2,1 and β-2, 6-D-fructosidic linkages, but their degree of polymerization were different. Meanwhile, pectins were also contained in these three drugs. AB is partial to immunomodulation while CO is partial to removing blood stasis. Fructans and pectins are the similar bioactive substance basis of AB, CO and AA whereas their structural difference might be contributed to the efficacy differentia of these three drugs. This study provides a better understanding on the profiles of polysaccharides from AB, CO and AA, further guiding their clinical usage and facilitating their quality control.