title: A new application of an aqueous diphase solvent system in one-step preparation of polysaccharide from the crude water extract of Radix Astragali by high-speed counter-current chromatography.
abstract: Polysaccharide's purification remains challenge to separation technology. Conventional methods involve time-consuming and complicated operations and always cause significant variation in the isolates' chemistry. This paper reports an aqueous diphase solvent system, namely PEG1000-MgSO(4)-H(2)O, which succeeded in one-step CCC separation of a polysaccharide (43 mg) from the water extract (1.67 g) of Radix Astragali. The solvent composition was set as 12:16:72 (w/w/w) of which the lower phase was used as the mobile phase at a flow rate of 0.8 mL/min in a 1000 mL column. The purified polysaccharide bears an average molecular weight of 1095 kDa and consists of galacturonic acid (76.5%), galactose (7.7%), arabinose (4.2%) and glucose (5.0%). Methylation analysis result showed it was composed of 58.4% of 1,4-linked Glcp, 11.8% of T-linked Araf, 10.5% of T-linked Glcp, 9.1% of 1,4,6-linked Galp and 5.1% of 1,3,6-linked Galp, etc. This success shows a short way between the crude water extract and purified polysaccharides, which minimizes the chemical variation caused by purification methods.
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Hong Kong Special Administrative Region, China.
authors.forename: Jun-Yi
authors.initials: JY
authors.lastname: Yin
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Jiang
authors.forename: Hua
authors.initials: H
authors.lastname: Yu
authors.forename: Ming-Yong
authors.initials: MY
authors.lastname: Xie
authors.forename: Wen-Luan
authors.initials: WL
authors.lastname: Hsiao
authors.forename: Ai-Ping
authors.initials: AP
authors.lastname: Lu
authors.forename: Quan-Bin
authors.initials: QB
authors.lastname: Han
mesh_terms: D027883:Astragalus Plant / Q000737:chemistry; D027885:Astragalus propinquus; D003377:Countercurrent Distribution / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D008278:Magnesium Sulfate / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011134:Polysaccharides / Q000032:analysis* / Q000302:isolation & purification*; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry
chemical_list: D004365:Drugs, Chinese Herbal; D011134:Polysaccharides; D014867:Water; D011092:Polyethylene Glycols; D008278:Magnesium Sulfate; C027492:Huang Qi