Polysaccharides

<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>