Rapid preparation and proton NMR fingerprinting of polysaccharides from Radix Astragali

The purity, content, and structure of the polysaccharides prepared from a specific medicinal plant are the fundamental basis to interpret the observed biological activities. An ultrafiltration-based method has been developed for rapid preparation of total and fractional polysaccharides from Radix Astragali in high yield and purity. This method involves extraction of plant material by hot water, treatment with Sevag reagent, and ultrafiltration using molecular weight cutoff concentrators. The prepared polysaccharides were assessed by 1H NMR spectroscopy, providing general purity, fingerprinting, and structural information. This method may be used to efficiently screen polysaccharides in plants.