Polysaccharides

<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>

<p>Hydroxyethyl cellulose (EHEC) is a non-ionic, water-soluble cellulose derivative produced by introduction of ethylene oxide groups to the hydroxyl groups of the cellulose backbone. Hydroxyethyl cellulose is useful as a water thickener, rheological control additive, protective colloid, binder, stabilizer, suspending agent and film former.  It is used in many industrial applications including latex paints, emulsion polymerization, petroleum, paper, pharmaceuticals, cosmetics and many other applications.</p>

<p>Sodium salt of a polysaccharide obtained from the brown seaweeds (e.g. Laminaria hyperborea, Fucus vesiculosus, Ascophyllum nodosum). The chemical structure consists of 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). Alginates form strong gels with divalent metal cations and the egg box model has been used to describe this form of gelation. The main use for alginate is in textile printing as a thickener in the printing of cottons with reactive dyes. In the food industry it is used as a thickener and gelling agent.  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.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</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>Gum arabic is an exudate gum picked from Acacia trees growing in tropical arid regions (typically Acacia senegal and Acacia laetia). The polysaccharide is branched with a main chain of (1-3) linked β-D-galactopyranosyl units with side chains of (1-3) β-D-galactopyranosyl units joined to it by (1-6) links. The side chains are 2-5 units in length. Both the main chain and the side chains have attached units of α-L-arabinofuranosyl, α-L-rhamnopyranosyl, β-D-glucuronopyranosyl and 4-O-methyl-β-D-glucuronopyranosyl units.</p>

<p>The polysaccharide, known as glucuronoxylomannan - produced by fruit bodies and in pure culture conditions - has been shown to consist of a mannan backbone that is glycosylated with xylan and glucuronic acid chains in a regular repeating structure. Laboratory tests have associated a number of biological activities with Cryptococcus neoformans glucuronoxylomannan, including immunostimulatory, antidiabetic, anti-inflammatory, hypocholesterolemic, hepatoprotective, and antiallergic effects.<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 Iiron with dextran, known as iron dextran, is used as a source of iron for baby piglets which are often anaemic at birth.</p>

<p>Rhodamine dextran (RD) is widely used as both an anterograde and retrograde tracer in neurons and for numerous other applications. It is biologically rather inert having α-1,6-linked glucose residues resistant to cleavage by most endogenous cellular glycosidases. It has low immunogenicity and makes an ideal long-term tracer for live cells. RD also serves as a valuable marker for cell loading of macromolecules by micro-injection, vesicular fusion, and electroporation, as well as for the uptake and internal processing of exogenous materials by phagocytotic and endocytic pathways.</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>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>Pustulan is a β-1,6-glucan isolated from Lasallia pustulata MW (20 kDa). It is recognized by the membrane bound Dectin-1, a C-type lectin-like pattern recognition receptor. Detection of β-glucans by Dectin-1 receptor leads to the CARD9-dependent activation of NF-κB and MAP kinases.  Studies have shown that pustulan can stimulate innate immune responses, inducing heat shock protein expression, eliciting phagocytosis, and production of pro-inflammatory cytokines.<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>A fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus serratus, Ascophyllum nodosum, Laminaria japonica (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>Fucoidan ≥ 95.0% Organic SO42- ≥ 20.0% Carbohydrate ≥ 70.0% L-Fucose ≥ 23.0% Alginic Acid ≤ 31.0% <br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Locust bean (carob) gum is the refined endosperm of the seed of the carob tree, an evergreen of the legume family (Ceretonia siliqua). The tree grows extensively in Spain and is cultivated in many other Mediterranean countries. Locust bean gum, like guar gum, is a galactomannan with a backbone of (1,4) β-D-mannopyranosyl units having branches of (1,6)-linked α-D-galactopyranosyl units. However, locust bean gum has substantially fewer side chains than guar gum and these are clustered in blocks leaving longer regions of unsubstituted mannosyl regions. The gum is only partially soluble in water and suspensions require heating before solubility is achieved. As with guar, the polysaccharide forms gels with other gums such as carrageenan and xanthan. Applications are in the food industry to enhance texture, in paper making and in the textile industry.</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 fucan sulphate found in brown marine algae (Phaeophyta-typically Fucus vesiculotus, Durvillea (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 approximately 27.9% and it also contains galactose (approx. 6.2%), uronic acid (approx. 22.4%) and sulfate (approx. 21.4%).<br>The image was kindly provided by Prof Mike Guiry from Cork who runs ‘The Seaweed Site’.</p>

<p>Scleroglucan is produced by the fermentation of the fungus Sclerotium rolfsii. It is a glucan with a main chain of 1,3-linked β-D-glucopyranosyl units with every third unit having a single β-D-glucopyranosyl unit linked 1,6. Scleroglucan powders disperse in water and give very viscous shear thinning solutions. Applications are in the oil industry in enhanced oil recovery, in agriculture in sprays and in the food and pharmaceutical industries.<br>The image was kindly provided by Dr. Chris Lawson.</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>