Medicinal Plants Classification Biosynthesis and ... - Index of

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3.5. Fingerprint
Jia Guan and Shao-Ping Li
It is complex, difficult and time consumable though structural information is
unambiguous identification of polysaccharides. Therefore, how to discriminate the
polysaccharides from different origins is crucial for quality control of polysaccharides. In last
decade, the profiling of the relative amounts of various active ingredients (i.e. fingerprint
profiling) has been shown to be a convenient and effective method for the quality control of
various herbal materials, especially when there is a lack of authentic standards for the
identification of all the active components present in these complex natural products [214-
217]. This technique is also successfully applied for the identification and characterization of
protein [218-222]. However, there are few reports for quality control of carbohydrates based
on their fingerprints. This is perhaps not surprising since the separation and detection of
carbohydrates, especially long-chain polysaccharides, is well known to be a highly
challenging and difficult analytical problem [223,224]. The sugar profiles of extracellular
polysaccharides, which were derivatised to alditol acetates and identified by GC, from
different Tremella species showed that all of the polysaccharides contained essentially the
same sugars but in different ratios [225]. The high-performance thin-layer chromatography
(HPTLC) peak profiles of acid hydrolyzates of carbohydrates from various Lingzhi
species/products were also demonstrated. The unique fingerprint patterns were observed in
the monosaccharide profiles between two highly valued Lingzhi species, Ganoderma
applanatum and Ganoderma lucidum, under total or partial acid hydrolysis conditions [226].
The three Angelica polysaccharides fractions were identified using HPLC after
hydrolysis and subsequently labeled with 1-phynyl-3-methyl-5- pyrazolone [195]. However,
the extent of acid hydrolysis is difficult to control and some monosaccharide could be
degraded under the acid conditions [227-229]. The ratio of monosaccharides obtained in acid
hydrolysate may be not in accordance with that in polysaccharides. Therefore, highly specific
enzymatic digestion of polysaccharides was developed, and a unique fingerprint of short
oligosaccharides was produced because the oligosaccharides of identical mass but different
monosaccharide composition do not co-migrate in the gels [230]. The oligosaccharides
released by enzyme hydrolysis were derivatised with a fluorophore at their reducing end, and
then separated by PACE [231] or CE [232]. The structural isomers of partially
methylesterified oligogalacturonides also can easily be separated and quantified using PACE
[233]. CE coupled with [234] or without [235] MS has also been widely applied for analysis
of polysaccharides. Furthermore, high performance GPC (HPGPC) was developed for quality
control of polysaccharides in natural and cultured Cordyceps [236], as well as Lingzhi
product [237]. Its application on analysis of enzymatically treated cellulose and related
polysaccharides has also been reviewed [238]. Lipid profile in meningococcal polysaccharide
was also determined using reversed-phase liquid chromatography. The capsular
meningococcal polysaccharide (MnPs) of Neisseria meningitidis is an antigenic component,
which is comprised of only even-chain fatty acids. Its purification must remove endotoxin, a
pyrogenic lipopolysaccharide impurity, which differs that the C12 and C14 fatty acids are
hydroxylated in the gamma position. Consequently, a fast and sensitive HPLC method using
fluorescence detection differentiates fatty acids provides an assay for both of these lipids,