Polissacáridos

<p>Chitosan is the deacetylated form of chitin. The polysaccharide is deacetylated in order to render it soluble, which is then possible at pH values of less than 7 (normally in dilute acid). This then allows the material to be used in a number of industrial applications as a binder and film former.</p>

<p>Dextran is α-(1,6)-linked α-D-glucan with α-(1,3)-linked glucose branch points produced by fermentation of Leuconostoc mesenteroides via the action of the enzyme dextransucrase on sucrose.  The main use for native dextran is as an extender in blood transfusions and products having a range of sharp cutoff molecular weights are produced commercially for this and other applications.  A complex of iron with dextran, known as iron dextran, is used as a source of iron for baby piglets which are often anaemic at birth.</p>

<p>Dextran sulphate is a dextran derivative whose ulcer (colitis) -causing properties were first reported in hamsters and extrapolated a few years later to mice and rats. The exact mechanisms through which dextran sulphate induces intestinal inflammation are unclear but may be the result of direct damage of the monolayer of epithelial cells in the colon, leading to the crossing of intestinal contents (for e.g. commensal bacteria and their products) into underlying tissue and therefore induction of inflammation.  The dextran sulphate sodium induced ulceration model in laboratory animals has some advantages when compared to other animal models of colitisdue to its simplicity and similarities to human inflammatory bowel disease.</p>

<p>Laminaran is a polysaccharide that co-occurs with fucoidan and alginate in brown seaweeds such as Laminaria digitata, Laminaria cloustoni, Eisenia bicyclis and Thallus laminariae. It is a β-1,3-linked glucan which it is claimed stimulates the immune system in mammals and fish.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>The main cell-wall components of baker’s yeast (Saccharomyces cerevisiae) as well as β-glucan are mannans with an α-1,6 mannose backbone and α-1,2 and α-1,3 mannose branches.<br>The image was kindly provided by Dr. Chris Lawson.</p>

<p>Dextran is α-(1,6)-linked α-D-glucan with α-(1,3)-linked glucose branch points produced by fermentation of Leuconostoc mesenteroides via the action of the enzyme dextransucrase on sucrose.  The main use for native dextran is as an extender in blood transfusions and products having a range of sharp cut-off molecular weights are produced commercially for this and other applications. A complex of iron with dextran, known as iron dextran, is used as a source of iron for baby piglets which are often anaemic at birth.</p>

<p>Chromogenic substrate for the measurement of endo-inulinase</p>

<p>Sephadex G-50 is a highly purified, high molecular weight, cellulose-based polymer that is used as a solid support in chromatography. The size of the gel particles can be varied by changing the concentration of the gel solution. It has a number of different uses, such as purification of proteins and other macromolecules, separation of DNA fragments, and the enzymatic synthesis of oligosaccharides. Sephadex G-50 is a synthetic material that is modified with organic or inorganic compounds to increase its chemical reactivity. This product can also be used for glycosylation and methylation reactions.</p>

<p>Dextran sulphate is a dextran derivative whose ulcer (colitis) -causing properties were first reported in hamsters and extrapolated a few years later to mice and rats. The exact mechanisms through which dextran sulphate induces intestinal inflammation are unclear but may be the result of direct damage of the monolayer of epithelial cells in the colon, leading to the crossing of intestinal contents (e.g., commensal bacteria and their products) into underlying tissue and therefore induction of inflammation.  The dextran sulphate sodium induced ulceration model in laboratory animals has some advantages when compared to other animal models of colitis, due to its simplicity and has many similarities to human inflammatory bowel disease.</p>

<p>Dextran is α-(1,6)-linked α-D-glucan with α-(1,3)-linked glucose branch points produced by fermentation of Leuconostoc mesenteroides via the action of the enzyme dextransucrase on sucrose.  The main use for native dextran is as an extender in blood transfusions and products having a range of sharp cutoff molecular weights are produced commercially for this and other applications.  A complex of iron with dextran, known as iron dextran, is used as a source of iron for baby piglets which are often anaemic at birth.</p>

<p>PolyGlycopleX (PGX) is produced from a mixture containing proprietary proportions of three polysaccharides, konjac glucomannan, xanthan gum and sodium alginate.  Recent hydrodynamic, rheological and analytical studies have shown that the unexpectedly high viscosity of solutions of PGX is consistent with an interaction between a konjac glucomannan, xanthan gum complex and sodium alginate to form a new, ternary complex in solution. Human and animal feeding studies have shown that PGX can be used to control weight, lower the glycaemic index of foods and postprandial glycaemia.</p>

<p>Pectin is a highly complex polysaccharide matrix that is found in the primary walls of dicotyledenous and monocotyledenous plants and gymnosperms, including soy plants. A key fragment of this complex is rhamnogalacturonan I, containing a backbone of the repeating disaccharide  [-4)-α-D-GalpA-(1,2)-α-L-Rhap-(1,]. Several applications for RG1 have been described including drug targeting to the colon via the oral administration route for local treatment of e.g. inflammatory bowel disease and colonic cancer. This has several advantages such as needle-free administration and low infection risk and in the gastro-intestinal tract RG-I is only degraded by the action of the colonic microflora.  High purity rhamnogalacturonan I is also used in research, biochemical enzyme assays and in vitro diagnostic analysis.</p>

<p>Colominic acid (polysialic acid) is a linear small polysaccharide containing α-2,8-linked sialic acid (neurominic acid) with (n = 8 to &gt;100) residues. Polysialic acid is an unusual post translational modification polysaccharide that is widely expressed in nature in bacterial capsules, fish, sea urchin eggs, embryonic tissues, amphibians, animal and human brains, and in a various cancers.  The major carrier of polysialic acids in mammals is the neural cell adhesion molecule (a glycoprotein that belongs to the immunoglobulin superfamily).Average molecular weight for this product is :50000-60000</p>

<p>Sodium carboxymethyl dextran is a white, odourless and tasteless powder, which is freely soluble in water or electrolyte solutions. Applications that have been described for carboxymethyl dextran include carriers of paramagnetic contrast agents, preparation of conjugates of pharmacologically active compounds and carboxymethyl dextrans in biosensors.  A number of other uses in cosmetics, agriculture, foods, paints and textiles have been the subject of patent applications.</p>

<p>Water thickener; rheological control additive; has industrial appplications</p>

<p>Gum karaya is exuded from Sterculia urens, a bushy tree found in dry regions of North India. Due to its extensive swelling capacity in water it is used as a laxative and as a denture adhesive. The structure consists of D-galactose, D-glucuronic acid and L-rhamnose but the detailed molecular structure is still incompletely known.</p>

<p>The disaccharide repeating unit of chondroitin sulphate consists of N-acetyl galactosamine sulphate linked β1,4 to glucuronic acid.  Each monosaccharide may be left unsulphated, sulphated once, or sulphated twice. The most common pattern has the hydroxyl groups of the 4 and 6 positions of the N-acetyl-galactosamine sulphated, with some chains having the position 2 of the glucuronic acid sulphated.</p>

<p>Food additive, applied in pharmaceuticals and beauty products.</p>

<p>In water, hydroxypropyl cellulose forms liquid crystals with many mesophases depending on concentration. These mesophases include isotropic, anisotropic, nematic and cholesteric, the latter resulting in many colors such as violet, green and red. Pharmaceutical applications include treatments for medical conditions such as dry eye syndrome (keratoconjunctivitis sicca), recurrent corneal erosions, decreased corneal sensitivity, exposure and neuroparalytic keratitis. It is also used as a binder in tablets. Hydroxypropylcellulose is also used as a thickener, a binder and emulsion stabiliser in foods with E number E463.  HPC is used as a support matrix for DNA separations by capillary and microchip electrophoresis.</p>

<p>Rhamnogalacturonan is a natural polysaccharide that is a major component of plant cell walls. It can be synthesized in the laboratory and modified with different functional groups to alter its properties. Rhamnogalacturonan has been shown to have anti-inflammatory, antioxidant, and immunomodulatory activities. It also has the ability to inhibit bacterial growth and stimulate phagocytosis by macrophages. This product has a high purity, is custom synthesized, and can be modified with different functional groups.</p>