Medicinal Plants Classification Biosynthesis and ... - Index of

Quality Control of Polysaccharides from Medicinal Plants and Fungi
Generally, a special gel for separation and a series of known molecular weight
polysaccharides as standards are necessary for calculating the molecular weight of the goal
polysaccharide, which depend on the calibration curve of the molecular weight and elution
volume [80-99]. However, a major drawback of SEC is the difficulty to obtain suitable
standards that possess the same hydrodynamic volume as the samples in the solution for
calibration curve. Combined with laser light scattering (LLS), SEC is conveniently applied
for determination of the molecular mass, molecular mass distribution and chain conformation
of polymers without the aid of standard samples [100-102]. In recent years, SEC-LLS in
combination with concentration detectors such as UV and RI has been demonstrated to be a
very powerful method for characterization and analysis of polysaccharides from medicinal
plants and fungus [103-106], which has superior accuracy of molar-mass determination
because the molar masses of polysaccharide estimated based on the secondary calibration of
standard dextrans is dependent upon initial assumptions about the behavior of the
polysaccharide fragments relative to standard compounds [107-109].
In addition, matrix-assisted laser desorption ionization time-of-flight mass spectrometry
(MALDI-TOF-MS) has proven to be an effective tool for the analysis of oligo- and
polysaccharides in last decade [110,111]. In combination with SEC, MALDI-MS has been
employed to obtain the average molar masses for polysaccharides [112,113]. Besides SEC,
field-flow fractionation (FFF) is a separation method suitable for the characterization of
macromolecules. Flow FFF connected to multi-angle light scattering detection (MALS) may
be a successful way to obtain molecular masses and distributions [114-117]. The methods for
measuring molecular weight of polysaccharides were shown in Table 2.
3.3. The Types and Ratios of Constituent Monosaccharides
Polysaccharide is a complex of different monosaccharides. Therefore, the types and
ratios of constituent monosaccharides are the basic and important structural characteristics of
polysaccharides. It was reported that the anticomplementary activity of fucan enhanced with
the increased contents of galactose and glucuronic acid, which suggested that these residues
should be essential [142].
Multiple linear regression analysis was used to deduce the correlation between the
monosaccharide composition ratios of polysaccharides isolated from 10 regionally different
strains of Lentinula edodes and their in vitro macrophage stimulatory activities [143]. The
results showed that the compositions of arabinose, xylose, mannose and galactose were
important. Especially, glucose, although presented in large compositions in all strains
presumably forms the backbone of the polysaccharide structures, is not the determinant factor
for either structural characteristics or that of the in vitro macrophage stimulatory activities.
The study offered a potential method for the elucidation of polysaccharide structures and
biological activities.
The types and molar ratios of constituent monosaccharides of polysaccharides are usually
determined using PC, TLC, GC, HPLC and CE methods. Prior to chromatographic
separation, acid hydrolysis (e.g. sulfuric acid, hydrochloric acid, or trifluoroacetatic acid i.e.
TFA) of polysaccharides and followed neutralization with sodium hydroxide, barium
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