Polissacáridos

<p>Polymannuronic acid is produced from alginates by partial hydrolysis and chromatography of brown algae such as Laminaria digitata, Ascophyllum nodosum and Fucus spp.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</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 is that the hydroxyl groups of the 4 and 6 positions of the N-acetyl-galactosamine are sulphated, with some chains having the position 2 of the glucuronic acid sulphated. Average molecular weight of 23,000 to 41,000</p>

<p>Sodium polymannuronate is produced from alginates by partial hydrolysis and chromatography of brown algae such as Laminaria digitata, Ascophyllum nodosum and Fucus spp.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>A linear β-(1,4)-galactan from potato tubers. Other linear β-(1,4)-galactans have been isolated from lemon peel, potato tubers and Norwegian acacia gum.</p>

<p>Xanthan gum is a polysaccharide produced by the Gram negative bacteria Xanthomonas campestris. It has unique rheological and gel forming properties and finds many applications particularly in the food and oil industries. Recently, it has been shown that ternary mixtures of konjac glucomannan, xanthan gum and sodium alginate can form a non-covalently linked complex which exhibits enhanced rheological properties of value in, for example, functional foods. The structure of xanthan is based on a cellulosic backbone of β-(1,4)-linked glucose units which have a trisaccharide side chain of mannose-glucuronic acid-mannose linked to every second glucose unit in the main chain. Some terminal mannose units are pyruvylated and some of the inner mannose units are acetylated.</p>

<p>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>Bacterial exopolysaccharide from gram negative Bacillus polymixa</p>

<p>In their simplest forms, xylans are linear homopolymers of β-1,4-xylose residues. In nature they are partially substituted by acetyl, 4-O-methyl-D-glucuronosyl and α-1,3 L-arabinofuranosyl residues, forming complex heterogenous and polydispersed glycans. An example of this is in the L-arabino (methyl-D-glucurono) xylan from corn cob.</p>

<p>Octyl-agarose is a type of agarose gel that has been modified to contain 20% ethanol solution. It is used in the purification of oligosaccharides and monosaccharides, as well as in the synthesis of complex carbohydrate. Octyl-agarose can be custom synthesized or modified with glycosylation, methylation, sugar, or carbohydrate modifications.</p>

<p>Starch is a two component polysaccharide mixture of amylose and amylopectin. Amylose is a linear polysaccharide of α (1,4)-linked glucose residues and averages 20 to 30% of the total in most native starches. Amylopectin is a highly branced glucan containing both a (1,4) and a (1,6) linkages. The number of glucose residues in a single starch molecule can vary from five hundred to several hundred thousand, depending on the type of starch. Starch is the major storage form of energy in plants, just as glycogen is the storage form of energy for animals. The plant directs the starch molecules to the amyloplasts, where they are deposited to form granules. Thus, both in plants and in the extracted concentrate, starch exists as granules varying in diameter from 2 to 130 μm.</p>

<p>Hydroxypropyl methylcellulose (HPMC or hypromellose) is a semisynthetic, inert and viscoelastic polymer that is used as eye drops and as semi-synthetic substitute for tear-films. When applied, a hypromellose solution acts to swell and absorb water, by increasing the thickness of the tear-film, resulting in decreased eye irritation.  In addition to its use in ophthalmic liquids, hypromellose has been used as an excipient in oral tablet and capsule formulations, where, depending on the grade, it functions as controlled-release agent. It is also used as a binder and as a component of tablet coatings.  Hypromellose in aqueous solution, unlike methylcellulose, exhibits thermal gelation properties. HPMC is approved as a food additive, emulsifier, thickening and suspending agent, and as an alternative to animal gelatin (Codex Alimentarius code (E number) is E464).</p>

<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>Hypromellose phthalate (hydroxypropyl methylcellulose phthalate, or HPMCP) is a phthalic acid ester of hydroxypropyl methylcellulose.  Hypromellose phthalate was introduced in 1971 as a cellulose derivative for enteric coatings, used to protect drugs from degradation by gastric acid or to prevent them from causing side effects in the stomach.  HPMCP is also used in sustained-release preparations, in binders and as microcapsule bases.</p>

<p>Lichenin, the poly β-D-Glucan of Cetraria islandica (Iceland moss), is found by enzymic degradation to differ in fine structure from the poly β-D-glucans of cereal grains. Thus, the basic structure of lichenin is a tetrameric unit in which two adjacent 1,4 linkages alternate with an isolated 1,3 linkage; occasionally four consecutive monomers are linked by 1,4 bonds. The immunomodulatory activity of isolichenan was tested in in vitro phagocytosis and anti-complementary assays, and proved to be active in both cases.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Schizophyllan is a neutral extracellular polysaccharide produced by the fungus Schyizophyllum commune. Schizophyllan is a β-1,3 beta glucan with β-1,6 branches and a molecular weight of around 450 kDa. It is reported that this polysaccharide can stimulate the immune system, chelate metals, act as an adjuvant in delivering drugs and aid in the production of nanofibres.<br>The image was kindly provided by Dr. Chris Lawson.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus serratus, Ascophyllum nodosum, Laminaria digitata (illustrated) and Macrocystis pyrifyra) and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</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 colitis, due to its simplicity and similarities to human inflammatory bowel disease.</p>

<p>Lambda-Carrageenan is a non-gelling sulphated galactan extracted from red seaweed (typically Gigartina stellata and Chondrus crispus). The structure of all carrageenans consists of a strictly alternating masked repeating unit of 1,3-linked α-D-galactose and 1,4-linked β-D-galactose. λ-Carrageenan has the α-linked unit 2-6-disulphated and the β-linked unit is 2-sulphated.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Gum tragacanth is an exudate gum from species of Astragalus trees mainly grown in Iran and Turkey. Tragacanth finds applications as an effective emulsifying and thickening agent in the food and pharmaceutical industries. The gum is a slightly acidic salt consisting of two fractions namely the water soluble tragacanthin and the fraction bassorin which swells in water to form a gel. Water soluble tragacanthin is reported as a branched arabiogalactan which is soluble in 70% ethanol. The acidic bassorin has a chain of (1,4)-linked a-D-galacturonic acid units some of which are substituted at O-3 with β-D-xylopyranosyl units and some of these being terminated with galactose or fucose.</p>

<p>Starch component; highly branched glucan</p>

<p>Chitin forms the tough fibrous exoskeletons of insects, crustaceans and other arthropods, and, in addition to its presence in some fungi, it occurs in at least one alga. The structure of chitin is similar to that of cellulose but with glucose replaced with N-acetyl-D-glucosaminyl units linked β-D-(1,4) in a linear chain. Chitin is normally produced from the shells of lobster, crab or shrimp.</p>

<p>The fluorescence intensity of these Rhodamine B isothiocyanate-dextrans varies much less than with FITC-dextrans.</p>

<p>Glycogen is a highly branched polysaccharide of glucose that serves as a form of energy storage in animals and fungi. It is the main storage form of glucose in the body.  In humans, glycogen is made and stored primarily in liver and muscle cells and functions as the second most important energy storage molecule to fat, which is held in adipose tissue. Glycogen is analogous to starch and has a structure similar to amylopectin, but is more extensively branched and compact than starch. It occurs as granules in the cytosol/cytoplasm in many cell types, and plays an important role in the glucose cycle.</p>

<p>Carboxymethyl cellulose is used in food as a viscosity modifier, thickener, to stabilise emulsions and are found in gluten-free and reduced-fat products. It is also a constituent of toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, and various paper products.  In laundry detergents, it is used as a soil suspension polymer. It is also used in pharmaceuticals as a thickening agent and in the oil-drilling industry as a viscosity modifier and water-retaining agent.</p>

<p>Tara gum is a galactomannan that is obtained from the seeds of the tara shrub Caesalpinia spinosa which is a native of the northern regions of Africa and South America. The gum is described as having a backbone of (1,4)-linked β-D-mannopyranosyl units one third of which possess a single unit side chain of (1,6)-linked α-D-galactopyranose. The gum forms gels with carrageenan and xanthan in a similar manner to guar and locust bean gum. Currently, only small quantities of tara gum are sold for use as food thickeners and stabilisers.</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 colitis due to its simplicity and similarities to human inflammatory bowel disease. <br>MW is in the range of 40,000Da</p>

<p>Hyaluronic acid, a polysaccharide with alternating β (1,3) glucuronide and β (1,4) glucosamine residues labelled with 5-amino-fluorescein gives a yellow fibrous product, which is soluble in both water and electrolytes.  Fluorescein-labelled hyaluronic acid can be used as a probe to follow the fate of hyaluronan in vitro and greatly enhances the visualisation of the permeation of substrates through skin and other tissues. Other applications of fluorescein-labelled hyaluronic acid have been reported in cancer research.</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>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus vesiculotus, Ascophyllum nodosum, Alaria and Macrocystis pyrifyra (illustrated) and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates, although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The fucose content of this fucan is approx. 31% and it also contains galactose (approx. 2.2%), uronic acid (approx. 12.4%) and sulfate (approx. 32.5%).<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>An apiose-rich pectic polysaccharide zosterin is found in the sea grass Zostera marina and is typical of similar structures occurring in higher plants. The structure consists of an α-1,4-D-galactopyranosyluronan backbone substituted by 1,2-linked apiofuranose oligosaccharides and single apiose residues. The average molecular mass of the polysaccharide has been shown to be about 4100 Da with a low polydispersity.</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>Pullulan is a glucan elaborated by the fungus Aureobasidium pullulans. The chemical structure is essentially repeating units of maltotriose joined by α-1,6 linkages. Pullulan dissolves readily in water to form stable, viscous solutions that do not gel. The polysaccharide can be moulded, made into fibres and forms clear soluble films. Applications are in foods as a low calorie ingredient and the polysaccharide forms water soluble films that have been used as seed coatings and to coat fruit. Pullulan can also be used in industrial applications as a binder, film former and in pharmaceutical applications.  Average MW is typically 100-200kDa.  Viscosity is ca 120 mm2/s.<br>The image was kindly provided by Dr. Chris Lawson.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus serratus, Ascophyllum nodosum (illustrated), Laminaria japonica and Macrocystis pyrifyra) and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Pectins are derived from citrus fruits such as lemons and limes. Amidated pectin is a modified form of pectin in which some of the galacturonic acid residues are converted with ammonia to amides. These pectins are more tolerant to varying calcium concentrations that occur in use and behave like low-ester pectins, need less of and are more tolerant to excess calcium. In addition, these gels are thermoreversible.</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>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 colitis, due to its simplicity and similarities to human inflammatory bowel disease.</p>

<p>Isolichenan is a cold-water soluble (1,3)-(1,4)-α-D-glucan isolated from lichen Cetraria islandica to have MW of about 6-8 kDa. Lichens produce isolichenan-type polysaccharides with considerable variation in linkage ratios as well as MW, even within the same species. Occasionally these α-glucans can be branched at O2, O3 or O6. The immunomodulating activity of isolichenan was tested in in vitro phagocytosis and anti-complementary assays, and proved to be active in both cases.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>A sulphated galactan from the red seaweeds (Gelidium spp.). The major gel-forming component agarose consisting of a linear chain of sequences of (1,3) linked β -D-galactopyranosyl units and (1,4 ) linkages to 3,6-anhydro-α-D-galactopyranosyl units. Gelation is via the formation of double helices.<br>Both Gelidium latifolium and Gelidium amansii are sources of both Agar (mixture of agarose and agaropectin) and Agarose. The images were kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</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 colitis, due to its simplicity and similarities to human inflammatory bowel disease.</p>

<p>Larch arabinogalactan is extracted from the heartwood of the western larch Larix occidentalis. This compound has a backbone of 1,3-linked β-D-galactopyranosyl units each of which contains a side chain at position C-6. Arabinogalactans are used as emulsifiers, stabilizers and binders in the food, pharmaceutical and cosmetic industries, as low viscosity dietary fibres and as a prebiotic fibres.</p>

<p>Gycosaminoglycan in many organs; joint lubricant and shock absorber</p>

<p>Iota-Carageenan is a gelling sulphated galactan extracted from red seaweed (typically Euchuma cottonii and Euchuma spinosum). The structure of all carrageenans consists of a strictly alternating masked repeating unit of (1,3) linked α-D-galactose and (1,4) linked β-D-galactose. The α-linked galactose occurs as a 3,6-anhydro-2-sulphate unit and the β-linked sugar occurs as the 4-sulphate.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Starch consists of two polysaccharides, amylose and amylopectin and represents approximately 20-25% of the total polysaccharide content in starch. Amylose molecules consist of single mostly unbranched chains of 500-20,000 α-(1-&gt;4)-D-glucose residues dependent on source (e.g. wheat, rice, potato, tapioca, etc). Amylose can form an extended shape (hydrodynamic radius 7-22 nm) but generally tends to wind up into a rather stiff left-handed single helix or form even stiffer parallel left-handed double helical junction zones. Hydrogen bonding between aligned chains causes retrogradation and releases some of the bound water (syneresis). The aligned chains may then form double stranded crystallites that are resistant to amylases. These possess extensive inter- and intra-strand hydrogen bonding, resulting in a fairly hydrophobic structure of low solubility. The amylose content of starches is thus the major cause of resistant starch formation.</p>

<p>Konjac glucomannan is an acetylated (1,4)-β-D-glucomannan obtained from the tubers of Amorphophallus konjac or Konnyaku root. It is widely used in foods, pharmaceuticals paints and explosives. It has been shown that ternary mixtures of konjac glucomannan, xanthan gum and sodium alginate can form a non-covalently linked complex which exhibits enhanced rheological properties of value in, for example, functional foods.</p>

<p>Carboxymethyl curdlan is widely used in the preparation of nanoparticles for biomedical applications. Following the synthesis of superparamagnetic iron oxide nanoparticles (SPIN) capped with carboxymethyl curdlan for use in cellular and in vivo imaging applications, the stability and dispersibility of SPIN in water were greatly improved with the introduction of the carboxymethyl curdlan moiety. Recently, a green and simple route was proposed to synthesize Ag nanoparticles using carboxymethylcurdlan under UV irradiation.</p>

<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>Galactomannan, food additive, fracking fluids, complex formation with Xanthan</p>

<p>Hydroxypropyl methylcellulose (HPMC or hypromellose) is a semisynthetic, inert and viscoelastic polymer that is used as eye drops and as semi-synthetic substitute for tear-films. When applied, a hypromellose solution acts to swell and absorb water, by increasing the thickness of the tear-film, resulting in decreased eye irritation.  In addition to its use in ophthalmic liquids, hypromellose has been used as an excipient in oral tablet and capsule formulations, where, depending on the grade, it functions as controlled-release agent. It is also used as a binder and as a component of tablet coatings.  Hypromellose in aqueous solution, unlike methylcellulose, exhibits thermal gelation properties. HPMC is approved as a food additive, emulsifier, thickening and suspending agent, and as an alternative to animal gelatin (Codex Alimentarius code (E number) is E464).</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 colitis, due to its simplicity and similarities to human inflammatory bowel disease.</p>

<p>Compression wood is a type of reaction wood formed on the underside of softwood stems when they are tilted from the vertical and on the underside of branches, which unlike normal wood contains significant amounts of β-(1,4)-galactan.</p>

<p>Polydextrose is a synthetic polymer of glucose. It is a food ingredient classified as soluble fibre by the U.S. Food and Drug Administration (FDA) as well as Health Canada, as of April 2013. It is frequently used to increase the non-dietary fibre content of food, to replace sugar, and to reduce calories and fat content. It is a multi-purpose food ingredient synthesized from dextrose (glucose), plus about 10 percent sorbitol and 1 percent citric acid. Its E number is E1200. It was approved by FDA in 1981.</p>

<p>Inulin is a prebiotic dietary fibre with a mildly sweet taste that promotes digestive health by supporting growth of healthy and balanced microbiota. In diagnostics, inulin is used for determining the glomerular filtration rate in functional kidney testing. Chemically, inulin is a chain of fructose molecules terminated at the reducing end with glucose. Thus, inulin is a fructan consisting of linear chains of β-(2,1) linked fructose residues, terminated at the reducing end by an α-D-(1,2)-glucopyranoside moiety.  It has a degree of polymerization typically between 2 and 60 (5). The β-(2,1) bond in inulin resists digestion in the gastrointestinal tract and is therefore responsible for its lower caloric value and beneficial effects on colon microbiota. A more functional form of inulin is produced by removing all fractions with chain lengths lower than 10.</p>

<p>A linear polyuronide obtained from the brown seaweeds (e.g. Laminaria hyperborea, Fucus vesiculosus, Ascophyllum nodosum). In the free acid form, the chemical structure consists of protonated blocks of (1,4) linked-β-D-polymannuronic acid (poly M), (1,4) linked-α-L-polyguluronic acid (poly G) and alternating blocks of the two uronic acids (poly MG).</p>

<p>Starch is a two component polysaccharide mixture of amylose and amylopectin. Amylose is a linear polysaccharide of α (1,4)-linked glucose residues and averages 20 to 30% of the total in most native starches. Amylopectin is a highly branced glucan containing both a (1,4) and a (1,6) linkages. The number of glucose residues in a single starch molecule can vary from five hundred to several hundred thousand, depending on the type of starch. Starch is the major storage form of energy in plants, just as glycogen is the storage form of energy for animals. The plant directs the starch molecules to the amyloplasts, where they are deposited to form granules. Thus, both in plants and in the extracted concentrate, starch exists as granules varying in diameter from 2 to 130 μm.</p>

<p>Hyaluronic acid is a polysaccharide composed of repeating units of the disaccharide N-acetylglucosamine and D-glucuronic acid. It is found in many connective tissues, including the skin, where it binds water and maintains elasticity. This product is custom synthesized by modifying the structure to include fluorine atoms, methyl groups, and monosaccharides. It is synthesized from synthetic building blocks that are modified with click chemistry to form oligosaccharides. The saccharide units are then glycosylated with sugar molecules, creating a complex carbohydrate with an average molecular weight between 50,000 and 100,000 Daltons.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus vesiculotus, Ecklonia (illustrated), Alaria and Cladosiphon) and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The fucose content of this fucan is approx. 19.0% and it also contains galactose (approx. 12.0%), uronic acid (approx. 25.5%) and sulfate (approx. 19.1%).<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Furcellaran (Danish agar) is similar to κ-carrageenan but is less sulphated (50%). It has been extracted from Furcellaria lumbricalis, which is mainly harvested off the coast of Denmark. This species, which is common to most parts of Europe, occurs as a loose form and only reproduces vegetatively.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Hydroxypropyl methylcellulose (HPMC or hypromellose) is a semisynthetic, inert and viscoelastic polymer that is used as eye drops and as semi-synthetic substitute for tear-films. When applied, a hypromellose solution acts to swell and absorb water, by increasing the thickness of the tear-film, resulting in decreased eye irritation.  In addition to its use in ophthalmic liquids, hypromellose has been used as an excipient in oral tablet and capsule formulations, where, depending on the grade, it functions as controlled-release agent. It is also used as a binder and as a component of tablet coatings.  Hypromellose in aqueous solution, unlike methylcellulose, exhibits thermal gelation properties. HPMC is approved as a food additive, emulsifier, thickening and suspending agent, and as an alternative to animal gelatin (Codex Alimentarius code (E number) is E464).</p>

<p>The polysaccharide has a linear structure and consists predominantly of repeating trisaccharide units, -O-(3-D-mannuronic acid-(1,4)-O-(3-D-glucopyranosyl-(1,4)-D-galactose. 50% of the hydroxyl groups are acetylated.  Extracted from a gram negative non pathogenic bacteria and then synthetic manipulation.</p>

<p>Methyl cellulose is a water-soluble polymer that is used as a binder or thickener in pharmaceutical, food, and ceramic processing applications. Methylcellulose has an unusual lower critical solution temperature (LCST) between 40 °C and 50 °C. At temperatures below the LCST it is readily soluble in water; above the LCST it is not soluble, which has a paradoxical effect that heating a saturated solution of methylcellulose will turn it solid, because methylcellulose will precipitate out. The temperature at which this occurs depends on DS-value, with higher DS-values giving lower solubility and lower precipitation temperatures because the polar hydroxyl groups are masked.</p>

<p>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>Gum ghatti is an exudate gum from the tree Anogeissus latifolia found in India and Sri Lanka. Applications are similar to Gum arabic in the food and pharmaceutical industries, where it is used as an emulsifier. The polysaccharide is reported to have an extremely complex structure which contains both oligosaccharides and polysaccharide elements. The polysaccharide contains Ara, Gal, Man, GlcA and Rha in a molar ratio of 61:39:6:10:6, a backbone of (1,6)-linked β-D-galactopyranosyl units and side chains of L-arabinofuranose units with some (1,4)-D-glucopyranosyluronic acid units, some joining (1,2)-D-mannopyranosyl units.</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>Curdlan is a microbial polysaccharide produced by a mutant strain of Alcaligenes faecalis var. myxogenes which was first shown to produce succinoglucan prior to mutation. Curdlan is a β-1,3 glucan forming clear solutions at about 55 °C which then gels (“low-set”) when cooled. Suspensions of curdlan at higher temperatures form firm resilient gels (“high set”) that melt at 140 - 160 °C.<br>The image was kindly provided by Dr. Chris Lawson.</p>

<p>‘Water kefir’ is a home-made beverage, which was thought to contain significant amounts of bacterial exopolysaccharides. It has now been reported that the exopolysaccharide fraction of this material contains dextrans with similar structures, having a number of (1,3) linkages, branched at positions O3 and position O2 and with a wide range of molecular weights.  In addition, it was shown that a small amount of levan is also present.</p>

<p>Pectic acid is non water-soluble β (1,4)-linked polygalacturonic acid. In its gel form, is water-soluble, transparent and gelatinous, and exists in ripe fruit and some vegetables. It is a product of pectin degradation in plants, and is produced via the interaction between pectinase and pectin (the latter being common in the wine-making industry).</p>

<p>Sodium carboxymethyl dextran (CM-dextran) is a white, odourless and tasteless powder, which is freely soluble in water or electrolyte solutions. The product has a pronounced polyanionic character, due to the high degree of carboxyl substitution.  Applications that have been described for CM-dextran include carriers of paramagnetic contrast agents, preparation of conjugates of pharmacologically active compounds and CM-dextrans in biosensors.  A number of other uses in cosmetics, agriculture, foods, paints and textiles have been the subject of patent applications.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically fucus vesiculosus (illustrated), Ascophyllum nodosum, Alaria and Macrocystis pyrifyra and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The fucose content of this fucan is approx. 43.1% and it also contains galactose (approx. 8.8%), uronic acid (approx. 8.7%) and sulfate (approx. 30.6%).<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Porcine mucosal heparin derivative; no anti-coagulant activity</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>Dermatan sulphate is a glycosaminoglycan found in skin, blood vessels, heart valves, tendons, aorta, spleen and brain and is usually isolated from pig skin or beef lung tissue. The disaccharide repeat unit is composed of L-iduronic acid and N-acetyl-galactosamine-4-sulphate linked β-(1,3) and β-(1,4). There are also small amounts of D-glucuronic acid.</p>

<p>Produced from starch; white hygroscopic spray-dried powder; easily digestible</p>

<p>Oat β-glucans are water-soluble β-glucans derived from the endosperm of oat kernels, which contain β-1,3 and β-1,4 linkages. They are known for cholesterol lowering and hypoglycemic properties, as well as their use in various cosmetic applications. Recent research has shown their potential application in immunomodulation and wound healing.</p>

<p>Dextran is α-(1,6)-linked α-D-glucan produced by fermentation of Leuconostoc mesenteroides via the action of the enzyme dextransucrase on sucrose. The main use for native dextran is as a blood plasma extender in blood transfusions. A complex of iron with dextran, known as iron dextran, is used as a source of iron to baby piglets which are often anaemic at birth.</p>

<p>Ivory nut mannan occurs in members of the custard apple, ebony and palm families - Ivory nut. The polysaccharide contains more than 95% mannose units linked β-(1,4) with a few a-D-galactopyranosyl units linked (1,6). It is widely used in foods, pharmaceuticals paints and explosives.</p>

<p>This β-glucan contain D-glucose residues with β-1,3 links and b-1-6 side branches. The frequency, location, and length of the sidechains may play a role in immunomodulation. Differences in molecular weight, shape, and structure of β-glucans can also affect the differences in biological activity. The water-soluble β-D-glucan is extracted from fruiting bodies of Piptoporus betulinus by hot aqueous extraction, followed by freeze-thawing and dialysis. Methylation analysis and NMR spectroscopy, indicated the presence of a β-D-glucan with a main chain (1,3)-linked, substituted at O-6 by single glucose residues.<br>The image was kindly provided by Dr. Chris Lawson.</p>

<p>Bacterial exopolysaccharide from gram negative Flavobacterium spp.</p>

<p>Gellan is a microbial polysaccharide produced by Pseudomonas elodea and generates gels with similar properties to agar. Gellan gum is a linear tetrasaccharide of (1,4)-β-L-rhamnopyranosyl, (1,3)-α-D-glucopyranosyl, (1,4)-β-D-glucuronopyranosyl, (1,4)-β-D-glucopyranosyl- with O(2) L-glyceryl and O(6) acetyl substituents on the 3-linked glucose. Both substituents are located on the same glucose residue, and on average, there is one glycerate per repeat and one acetate per every two repeats. In low acyl gellan gum, the acyl groups are removed completely. The high acyl form produces soft, elastic, non-brittle gels, whereas the low acyl form produces firm, non-elastic, brittle gels.</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>Sodium carboxymethyl dextran (CM-dextran) is a white, odourless and tasteless powder, which is freely soluble in water or electrolyte solutions. The product has a pronounced polyanionic character, due to the high degree of carboxyl substitution.  Applications that have been described for CM-dextran include carriers of paramagnetic contrast agents, preparation of conjugates of pharmacologically active compounds and CM-dextrans in biosensors.  A number of other uses in cosmetics, agriculture, foods, paints and textiles have been the subject of patent applications.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus vesiculotus, Ascophyllum nodosum, Alaria and Cladosiphon (illustrated) and has been shown to have anticoagulant activity. The main constituents are α-1,4 and α-1,2 linked L-fucose sulphates although galactose also occurs and there are many variations of the basic structure found in different species of Phaeophyta.<br>The fucose content of the fucan is approx. 51% and it also contains galactose (approx. 6.3%), uronic acid (approx. 15.5%) and sulfate (approx. 25%).<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Xylan is the most abundant noncellulosic polysaccharide present in both hardwoods and annual plants. Xylan is found mainly in the secondary cell wall as part of the hemicellulose fraction and is considered to form an interface between lignin and other polysaccharides. In their simplest forms, xylans are linear homopolymers of β-1,4-xylose residues but can also form complex heterogenous and polydispersed glycans.</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>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>