Polysaccharides

<p>Viscoelastic polymer; excipient; food additive</p>

<p>Teichuronic acid is isolated from the cell walls of Micrococcus luteus. The structure has been elucidated as [ManNAcUAp-(β-1,6)-Glcp-(α -1,4)]n.</p>

<p>Viscoelastic polymer; excipient; food additive</p>

<p>Anterograde and retrograde tracer in neurons; biologically inert</p>

<p>Fluorescein isothiocyanate dextran is a fluorescent derivative of a dextran fraction with an average molecular weight of approximately 4000. It is supplied as a yellow powder which is readily soluble in water.</p>

<p>Pectin is a highly complex polysaccharide matrix that is found in the primary walls of dicotyledenous and monocotyledenous plants and gymnosperms, including potato. 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 colon cancer.  This has several advantages such as needle-free administration and low infection risk. 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>Methyl cellulose is a synthetic polymer of cellulose. It is prepared by treating the natural polymer with a methylating agent, such as dimethyl sulfate. Methylation is carried out in the presence of an acid catalyst to produce mainly methyl ethers and methyl esters. The degree of substitution may be controlled by the amount of catalyst. Methyl cellulose is used as a thickener, emulsifier, or stabilizer in many food products, including ice cream and toothpaste.</p>

<p>Complex glucan (a 1-6) from Leuconostoc spp.; extender in blood transfusions.</p>

<p>Low calcium heparin is a glycosaminoglycan, which occurs in many mammalian tissues and has important anticoagulant and thrombolytic properties. The chemical structure is composed mainly of two disaccharide repeating units A and B. A is L-iduronic acid 2-suplhate linked α-(1,4) to 2-deoxy-2-sulfamido-D-galactose 6-sulphate, while B is D-glucuronic acid β-(1,4) linked to 2-deoxy-2-sulfamido-D-glucose 6-sulphate.</p>

<p>Fluorescein isothiocyanate carboxymethyl dextran (FITC-CM Dextran) has been reported to provide a valuable carrier for nanoparticles of iron oxide.  These products provide a potent tool for contrast enhancement in magnetic resonance imaging.</p>

<p>Cellulose acetate phthalate (CAP) finds use in the formulation of pharmaceuticals, such as the enteric coating of tablets or capsules and for controlled release formulations, where it is often used with other coating agents such as ethyl cellulose.  It contains about 50% acetate and 25% as the phthalate ester with the rest as free hydroxyl groups.  Enteric coatings based on CAP are resistant to acidic gastric fluids, but easily soluble in mildly basic medium of the intestine. The pH-sensitive solubility of CAP is mainly determined (as are other properties of this mixed ester) by the degree of substitution and by the molar ratio (acetyl and phthaloyl groups).</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>A linear β-(1,4)-galactan from Acacia gum. Other linear β-(1,4)-galactans have been isolated from lemon peel, potato tubers and Norwegian spruce compresssion wood.</p>

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

<p>Xyloglucans are members of a group of polysaccharides typically refered to as hemicelluloses. Hemicelluloses are plant cell wall polysaccharides that are not solubilized by water but are solubilized by aqueous alkali (e.g. 1 and 4M KOH). Other hemicellulosic polysaccharides include xylan, glucuronoxylan, arabinoxylan, mannan, glucomannan and galactoglucomannan. Hemicelluloses have a backbone of 1,4-linked β-D-pyranosyl residues in which O4 is in the equatorial orientation (e.g. Glc, Man, and Xyl). Xyloglucan is the predominant hemicellulose in the primary walls of dicots and non-graminaceous monocots and may account for up to 20% of the dry weight of the primary wall. Xyloglucan has a backbone composed of 1,4-linked β-D-Glcp residues. Up to 75% of these residues are substituted at O6 with mono-, di-, or triglycosyl side chains.</p>

<p>Fluorescein isothiocyanate carboxymethyl dextran (FITC-CM Dextran) has been reported to provide a valuable carrier for nanoparticles of iron oxide.  These products provide a potent tool for contrast enhancement in magnetic resonance imaging.</p>

<p>The extracellular polysaccharide produced by Arthrobacter stabilis NRRL B-3225 contains D-glucose, D-galactose, pyruvic acid, O-succinyl, and O-acetyl in the approximate molar ratio of 6:3:1:1:1.5. Succinyl is linked as its half-ester, making it readily removable. The viscosity of aqueous, salt-free solutions of both native and deacylated polymer is relatively low, but atypical of anionic polysaccharides, increases rapidly in the presence of salts, acids, or alkali.</p>

<p>Fluorescein isothiocyanate carboxymethyl dextran (FITC-CM Dextran) has been reported to provide a valuable carrier for nanoparticles of iron oxide.  These products provide a potent tool for contrast enhancement in magnetic resonance imaging.</p>

<p>Ulvans are structural polysaccharides present in the cell walls of green algae such as Ulva armoricana, Ulva rotondata, Ulva rigida, Ulva lacterca and Ulva pertusa. They are highly sulphated and contain rhamnose 3-sulphate, xylose, xylose 2-sulphate, glucuronic acid and iduronic acid residues.  Ulvan has several potentially valuable functionalities such as gel formation for agricultural and food applications. It has also an anticoagulant, antioxidant, antihyperlipidemic and antitumor activities that are attractive for pharmaceutical applications.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</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>