Isolation, structures and bioactivities of the polysaccharides from Radix Hedysari: A review

Radix Hedysari, a well-known traditional Chinese herbal medicine, has a long history as a medicinal plant in China based on its wide spectrum of biological and pharmacological activities. Until now, many chemical constituents have been isolated and identified from Radix Hedysari, such as polysaccharides, flavonoids, phenylpropanoids, trace elements and so on. Of these, Radix Hedysari polysaccharides are one of the most important active compounds of the Radix Hedysari and have various biological activities, including anti-tumor activity, antioxidant activity, anti-diabetic activity, immunity enhancement effect and regulation of intestinal flora. These beneficial biological activities are related to the chemical structure of the Radix Hedysari polysaccharides. The chemical structure of HPS is the basis of its biological activity, which is affected by many factors, such as the composition of monosaccharide, the size of relative molecular weight, the way of glycoside bond connection, the three-dimensional structure of polysaccharide, and so on. Different extraction and separation methods lead to different configurations of polysaccharides and different biological activities of polysaccharides. In general, the bioactivity of polysaccharides showed a certain dose-response or structure-activity relationship. At present, few studies of regarding the structure-function relationships of these polysaccharides have been reported, and it is not easy to relate the structures of HPS to their biological activities. Nevertheless, some relationships can be inferred as follows. This article is aimed to provide a systematic and up-to-date review on the extraction, purification, structural characterization, and biological activities of the Radix Hedysari polysaccharides to support its further therapeutic potentials and sanitarian functions. Furthermore, the possible development and a perspective for future research of Radix Hedysari polysaccharides are also discussed.