[Isolation, purification and identification of polysaccharides from Gynura divaricata]

The purpose of this study was to isolate and purify polysaccharide from Gynura divaricata and analyze its monosaccharide composition. A water-soluble crude polysaccharide was obtained by hot water extraction, ethanol precipitation and deproteinization after degreasing. The crude polysaccharide then purified with DEAE-Sepharose Fast Flow column chromatography and dialysis. The monosaccharide composition and structure were analyzed by HPLC, UV spectrophotometer and 1H-NMR. The results showed that the purity and molecular weight of GDPS-2 and GDPS-3 were 87.3%, 2.03 x 10(4) Da and 90.9%, 4.29 x 10(4) Da, respectively. The UV spectrophotometer and 1H-NMR data suggested that glycosidic bond of GDPS-2 and GDPS-3 were a type. Both GDPs-2 and GDPs-3 were homogeneous polysaccharides, and GDPs-2 was mainly composed of glucuronic acid and xylose at a molar ratio of 1.1:0.63. GDPs-3 was mainly composed of rhamnose, glucuronic acid, galactose, xylose and galacturonic acid at a molar ratio of 0.32:6.0:0.21:1.75:4.3.