Characterization and Antioxidant Activities of Polysaccharide Isolated fromLinggui Zhugan Tang / 中国实验方剂学杂志

ABSTRACT

Objective:To characterize the structure of polysaccharide isolated from Linggui Zhugan Tang（LGZGT）,including monosaccharide composition and functional group detection, investigate the difference of the antioxidant activities of crude polysaccharide（CP） and pure polysaccharide（PP）, and provide the basis for the quality evaluation of LGZGT by in vitro bioassay. Method:The average molecular weight of CP was analyzed by high performance gel chromatography（HPGPC）. Gas chromatography-mass spectrometry（GC-MS） and fourier transform infrared（FT-IR） were employed to determine the structure of the polysaccharide. The antioxidant activities of CP and PP samples were evaluated on the basis of 1-diphenyl-2-picrylhydrazyl（DPPH） radical scavenging activity and OH radical scavenging activity. Result:The total polysaccharide was composed of single peaks, with a molecular weight of 3 689 Da. It was mainly composed of arabinose, mannose, glucose, galactose and fructose with a molar ratio of 6.85∶1.00∶109.21∶1.04∶21.82. Among them，glucose and fructose were the predominant components. In addition， IR study indicated the presence of pyranose and anomeric configurations in glycan structure, with two stereoisomers of glycosidic bond (α-glycosidic bond and β-glycosidic bond). It was found that the total polysaccharide had the ability of scavenging DPPH and hydroxyl radicals, and the activity of crude polysaccharide was better than that of refined polysaccharide. It was found in antioxidant research that the total polysaccharide had the ability of scavenging DPPH and hydroxyl radicals, and the activity of CP was better than that of PP. Furthermore, LC-Q-TOF-MS was used to qualitatively analyze the other components in CP, which indicated that it was related to the adsorption of pentacyclic triterpenoids in Glycyrrhiza uralensis. Conclusion:The polysaccharides and pentacyclic triterpenoids in LGZGT are the material basis for the antioxidative effect of LGZGT. The antioxidative activity determined by in vitro bioassay can be used as an evaluation index for the overall quality control of LGZGT.