Extractable polysaccharides

The dependence of the amount of starch in woody tissues of various trees on season (see, for example, 72, 110), sunlight (see, for example, 122), foliation (see, for example, 178), nutrients (see, for example, 122), and the demand for monoterpene biosynthesis to repel insect attack (178) has been investigated as expected, the starch content is directly proportional to the availability of translocatable carbohydrates from photosynthesis and inversely proportional to energy demands for anabolic processes. 

The xylem ray cells of the sugar maple (Acer saccharum) contain -10% starch (172). In birch (Betula spp.) stored starch is converted into sucrose when the ambient temperature drops to - 5 °C (50), perhaps to provide cryoprotection. 

The other commercial importance of starch in woody tissue relates to the correlation between the presence of starch in felled timber and susceptibility to attack by insects and fungi (177). 

The most abundant polysaccharide of woody tissue is cellulose. Next in overall amount is the class of structurally diverse substances called hemicelluloses, which 

Other polysaccharides are less associated and can be obtained by simple extractions of the tissue. The few known examples are given here. It must be recognized that only a few species have been investigated for extractable polysaccharides. 

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The same methods (chemicals, enzymes, physical treatments) can be also applied on the cell wall materials not with the aim of extracting polysaccharides but with the aim of obtaining modified fibres. New properties concerning for exemple fermentability, ratio soluble/insoluble dietary fibre, hydration., can be obtained (1). 

Viscosity measurements of the extracted polysaccharides cross-linked at increasing concentrations showed a clear increase in relative viscosity, when the cross-linking reaction took place at concentrations higher than 0.5 % (Fig. 4). At a concentration higher than 1.5 % a gel was formed. 

Assinewe VA, Arnason JT, Aubry A, et al (2002) Extractable polysaccharides of Panax quinquefolius L. (North American ginseng) root stimulate TNFa production by alveolar macrophages. Phytomedicine 9 398 04... 

We have studied the effect of irradiation on both pectin and cellulose degradation extensively, both from the standpoint of the in vivo degradation as measured by the characteristics of the extracted polysaccharides 13, 16) and in model systems utilizing in vitro techniques 10, 12, 14, 26,... 

Two mannans may be isolated from ivory nuts. Mannan A, which is extracted with alkali, occurs in granular form,94 96 and x-ray diffraction photographs of both the native and the extracted polysaccharide show distinct crystalline patterns.96 Mannan B cannot, however, be extracted directly, and it is separated from cellulose by precipitation from cupram-monium solution.91 In the plant, mannan B is built up of microfibrils analogous to those of cellulose, but the extracted polysaccharide shows no tendency to crystallize on precipitation.95... 

S. H. Knutsen and H. Grasdalen, Characterization of water-extractable polysaccharides from Norwegian Furcellaria lumbricalis (Huds.) Lamour. (Gigartinales, Rhodophyceae) by IR and NMR spectroscopy, Bot. Mar., 30 (1987) 497-505. 

L. Stoloff and P. Silva, An attempt to determine possible taxonomic significance of the properties of water extractable polysaccharides in red algae, Econ. Bot., 11 (1957) 327-330. 

Ultrasonic-assisted extraction (UAE) is the other common method that accelerates the extraction process [83]. The principle behind the UAE is similar to MAE, where the cell wall is destroyed by ultrasound that leads to active constituents being leached out from ruptured cells without modifying the polysaccharides. In general, UAE is able to extract polysaccharides at lower temperatures, which is about 25-70 °C at 120/300 W of ultrasonic power [89]. The extraction time is between 5 and 40 min. 

The literature demonstrates that ultrasonic extraction is more efficient with shorter extraction time than the classical method and provides higher yield (Table 1) [71]. This was confirmed by the extraction of polysaccharides from mulberry leaves using ultrasonic method [87]. UAE is therefore a promising alternative technique for the extraction of natural polysaccharides from botanical sources [87,89]. Correct use of UAE method preserves the structural elements of the extracted polysaccharides. If the applied ultrasonic power, irradiation time, and reaction temperature are too high, the extracted polysaccharides are likely to degrade and their structures may not be preserved which leads to changes in their biological properties [89]. 

In general, MAE and UAE methods have improved time-efficiency, reduced solvent consumption, and improved yield of extracted polysaccharides [86,89]. UAE combined with MAE has been shown to further improve the yield [88]. However, because of cost-efficiency and simplicity, the classical hot water extraction procedure has been widely used for the extraction of polysaccharides for industrial and laboratory applications [2,5,71-77]. 

As discussed earlier, it is of great future interest to undertake systematic and targeted screening programs to discover antioxidant, immtmomodulatory, and antitumor polysaccharides. Toward this end, the development of efficient separation and purification techniques for plant-extracted polysaccharides is an important future direction. 

Water-unextractable arabinoxylans (1 wt.%,) Water extractable polysaccharides (50 mg mL )... 

Species methodology of extraction Polysaccharide structure Functionality and properties References... 

Particulate matter may thus be characterized by three different sugar fractions extractable monosaccharides, extractable polysaccharides Le., starch-like substances) and total sugars after hydrolysis (including monosaccharides, starches and structural polysaccharides). An analogous approach may also be adopted to characterize three different amino acid fractions of particulate matter by employing the common analytical techniques of Section 26.3. 

Wagner H, Jurcic K (1996) A new flowcytometric assay for measuring the leukocyte phagocytosis activity of immunostimulating plant extracts, polysaccharides and various low molecular weight compounds. Phytomedicine 3 (Suppl 1) 31... 

Arabinogalactan occurs in high concentration (5% to 35%, dry weight basis) in the heartwood of many species of Larix, a deciduous conifer native to the temperate and subarctic zones of the Northern Hemisphere in fact, the presence of this water-soluble, easily extractable polysaccharide is characteristic of Larix spp. Larch arabinogalactan will accumulate in masses under the bark as a result of injuries however, this supply is limited and its collection is difficult. 

Bauer and Wagner concluded that the immunostimulatory activity of alcoholic and aqueous extracts depend on the combined action of several constituents. In lipophilic fractions, alkylamides and the polar caffeic acid derivative cichoric acid contribute to activity of alcoholic extracts. Polysaccharides are implicated in the expressed juice of E. purpurea and aqueous extracts, as well as orally administered powdered whole drug. ... 

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