Separation By Simulated Moving Bed Ion-exchange Chromatography And Structure Determination Of Taxus Polysaccharides

Not only taxol,but also other bioactive materials, such as polysaccharides, were included in Tuxus. chinensis var.mairei. Bioactive water-soluble polysaccharides,Taxus polysaccharides,were extracted from the leaves of Taxus with hot water.This paper studies the extraction,decoloration and separation of Taxus polysaccharides, separation of a fraction by Simulated Moving Bed Ion Exchange Chromatagraphy(SMB)and the structure determination of this fraction.Taxus polysaccharides were extracted with hot water and alcohol precipitation. Experoment of L⁹(3⁴) were investigated and the optimal extracting conditions were temperature 100℃,time 2h, solid:liquid ratio 1:30,and alcohol concentration 85% and the yield of Taxus polysaccharides was 4.68%.Decoloration researches were conducted with ultrafiltration membrane and the retention rate and decolorization rate of Taxus polysaccharide were 75.6% and 87.2% under those conditions: temperature 25℃,pressure 20psi,pH6.8,concentration 10g/L and repeated the operation four times; One main fraction of Taxus Polysaccharides was obtained by eluting with 0.3N Tirs-HCl NaCl buffer from DEAE-Sepharose-FF ion-exchange column and GPC showed that the fraction was homogeneous and this polysaccharides was named PST-1.Separation of PST-1 by SMB was investigated.The SMB equipment was designed and developed by ourselves and the control parameters of programmable logic controller(PLC) were optimized through nonlinear techniques by PCSS software.The treatment capacity and liner velocity of the equipment were 100L/d and 4.17L/h and the average purity and recovery rate of product could achieve 99% and 50.9% under the optimal conditons;Analysis of 72 hours' test data showed the technical parameters were stable and met the request of industry.By means of GPC,IR,GC-MS,¹³CNMR,¹HNMR,Methylation analysisetc,structural properties of PST-1 were identified as follows:The Mw(Average Molecular Weight)of PST-1 was 3.44×10⁶ Da and its optical rotation was [α]_D²⁰=+0.110°(c0.1, H₂O); PST-1 constituted 8 simple sugars and the molar ratio was (including uronic acid) 2,4-Dimethoxy-Mannose:Rhamnose:Ara-binose:Xylose:Galactose:D-Galacturonic acid:Mannose:D-glucuronic acid=2%:5%:24%:9%:3%:1%:46%:10%;The chief bone of PST-1 was 1,3,6-linked-β-D-Man residue and the side chains contained Furanoid and Pyranoid residues.