Medicinal Plants Classification Biosynthesis and ... - Index of

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Jia Guan and Shao-Ping Li
polysaccharides are separated by gel filtration (Figure 2). Ultrafiltration is also used for
fractionation of polysaccharides with different molecular size or for removal of low
molecular weight compounds coextracted.
3. Qualitative Analysis of Polysaccharides
Qualitative analysis is used to distinguish the polysaccharides using their structural,
physical and chemical properties.
Filtrate
Purified neutral
polysaccharides
Raw material
Plant residue
Step precipitation with ethanol
(final concentration, 30%~80%)
Supernatant Precipitate
Non-absorbed Fr.
(fraction 1, 2, …)
GFC
IEC
Remove lipophilic and low molecular
weight compounds with organic solvents
Hot water extraction
Residue
Absorbed Fr.
GFC
Purified Acidic or
conjunctive
polysaccharides
Plant residue
Extract with dilute base
Filtrate
GFC
Purified acidic
polysaccharides
Figure 2. Diagrammatic scheme of isolation, fractionation and purification of polysaccharides from raw
materials IEC, ion-exchange chromatography; GFC, gel filtration chromatography.
3.1. Purity
Purity is crucial for determination of polysaccharide‘s properties. Because its complex
and specification, the purity elucidation of polysaccharides is very different from the low
molecular weight compounds. For example, melting point and solubility are usually not