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ALGIN
Alginic acid ; potassium alginate ; sodium alginate
CAS number: 9005-38-3 / 57606-04-9
EC number: 232-680-1
Alginic acid, also called algin, is a polysaccharide distributed widely in the cell walls of brown algae that is hydrophilic and forms a viscous gum when hydrated. With metals such as sodium and calcium, its salts are known as alginates. Its colour ranges from white to yellowish-brown. It is sold in filamentous, granular, or powdered forms. It is a significant component of the biofilms produced by the bacterium Pseudomonas aeruginosa, a major pathogen found in the lungs of some people who have cystic fibrosis. The biofilm and P. aeruginosa have a high resistance to antibiotics, and are susceptible to inhibition by macrophages.
Synonyms:
Alginic Acid Sodium Salt ; SODIUM ALGINATE ; ALGIN ; potassium alginate ; alginic ; acid ; algin ; Acid Algin G 2 ; alginate ; Kelacid ; Landalgine ; Norgine ; OligoG ; Polymannuronic acid ; Protanal LF ; Satialgine-H 8 ; Sazzio ; Snow acid algin G ; Verdyol Super ; 1444006-48-7 ; 210888-24-7 ; 545434-56-8 ; 865838-47-7 ; 865838-48-8 ; 9005-32-7 ; Sodium Salt of Alginic Acid ; sodium alginate ; 9005-38-3 ; sodium;3,4,5,6-tetrahydroxyoxane-2-carboxylate ; natriumglucuronat ; Alginic acid monosodium salt ; sodium;(2S,3R,4S,5R)-tetrahydroxyoxane-2-carboxylate ; SCHEMBL20919851 ; EBD39195 ; FT-0621962 ; FT-0670280 ; 6-(2-carboxy-4,5-dihydroxy-6-methoxyoxan-3-yl)oxy-4,5-dihydroxy-3-methoxyoxane-2-carboxylic acid ; 9005-34-9 ; 3-((6-carboxy-3,4-dihydroxy-5-methoxytetrahydro-2H-pyran-2-yl)oxy)-4,5-dihydroxy-6-methoxytetrahydro-2H-pyran-2-carboxylic acid ; Alginic acid, ammoniumsalt ; SCHEMBL10118904 ; AKOS015915207 ; A843434 ; 6-[(2-carboxy-4,5-dihydroxy-6-methoxy-3-oxanyl)oxy]-4,5-dihydroxy-3-methoxy-2-oxanecarboxylic acid ; 6-[2-carboxy-6-methoxy-4,5-bis(oxidanyl)oxan-3-yl]oxy-3-methoxy-4,5-bis(oxidanyl)oxane-2-carboxylic acid
Alginates are refined from brown seaweeds. Throughout the world, many of the Phaeophyceae class brown seaweeds are harvested to be processed and converted into sodium alginate. Sodium alginate is used in many industries including food, animal food, fertilisers, textile printing, and pharmaceuticals. Dental impression material uses alginate as its means of gelling. Food grade alginate an approved ingredient in process and manufactured foods.
Gum derived from alginic acid which is obtained from brown seaweed genera, such as Macrocystis pyrifera. The derivatives are sodium, ammonium, and potassium ates of which the sodium salt is most common. They are used to provide thickening, gelling, and binding. A derivative designed for improved acid and calcium stability is propylene glycol ate. The s are soluble in cold water and form nonthermoreversible gels in reaction with calcium ions and under acidic conditions. Algin is used in ice cream, icings, puddings, dessert gels, and fabricated fruit.
Alginic acid is a hydrophilic colloid carbohydrate that occurs naturally in the cell walls and intercellular spaces of various species of brown seaweed (Phaeophyceae). The seaweed occurs widely throughout the world and is harvested, crushed, and treated with dilute alkali to extract the alginic acid.
Alginic Acid is the acidic, insoluble form of algin that is a white to yellowish fibrous powder obtained from brown seaweed genera, such as macrocystis pyrifera. the derivatives are soluble and include sodium, potassium, and ammonium alginate and propylene glycol alginate. it is used as a tablet disintegrant and as an antacid ingredient.
Brown seaweeds range in size from the giant kelp Macrocystis pyrifera which can be 20–40 meters long, to thick, leather-like seaweeds from 2–4 m long, to smaller species 30–60 cm long. Most brown seaweed used for alginates are gathered from the wild, with the exception of Laminaria japonica, which is cultivated in China for food and its surplus material is diverted to the alginate industry in China.
Alginates from different species of brown seaweed vary in their chemical structure resulting in different physical properties of alginates. Some species yield an alginate that gives a strong gel, another a weaker gel, some may produce a cream or white alginate, while others are difficult to gel and are best used for technical applications where color does not matter.
Alginate is a natural hydrocolloid extracted from brown seaweed. It provides gelling, thickening and film-forming properties for a number of food and non-food applications.
The Alginate range comprises alginic acid, from which our alginate salts and blends are made, especially designed to meet applications needs.
Commercial grade alginate are extracted from giant kelp Macrocystis pyrifera, Ascophyllum nodosum, and types of Laminaria. Alginates are also is produced by two bacterial genera Pseudomonas and Azotobacter, which played a major role in the unravelling of its biosynthesis pathway. Bacterial alginates are useful for the production of micro- or nanostructures suitable for medical applications.
Sodium alginate (NaC6H7O6) is the sodium salt of alginic acid. Sodium alginate is a gum.
Potassium alginate (KC6H7O6 ) is the potassium salt of alginic acid.
Calcium alginate (C12H14CaO12 ), is made from sodium alginate from which the sodium ion has been removed and replaced with calcium.
The manufacturing process used to extract sodium alginates from brown seaweed fall into two categories:
1)Calcium alginate method
2) Alginic acid method.
Chemically the process is simple, but difficulties arise from the physical separations required between the slimy residues from viscous solutions and the separation of gelatinous precipitates that hold large amounts of liquid within the structure so they resist filtration and centrifugation.
Alginate absorbs water quickly, which makes it useful as an additive in dehydrated products such as slimming aids, and in the manufacture of paper and textiles. It also is used for waterproofing and fireproofing fabrics, in the food industry as a thickening agent for drinks, ice cream, cosmetics, and as a gelling agent for jellies. Sodium alginate is mixed with soybean flour to make meat analogue.
Alginate is used as an ingredient in various pharmaceutical preparations, such as Gaviscon, in which it combines with bicarbonate to inhibit reflux. Sodium alginate is used as an impression-making material in dentistry, prosthetics, lifecasting, and for creating positives for small-scale casting.
Sodium alginate is used in reactive dye printing and as a thickener for reactive dyes in textile screen-printing.[citation needed] Alginates do not react with these dyes and wash out easily, unlike starch-based thickeners. As a material for micro-encapsulation.
Calcium alginate is used in different types of medical products, including skin wound dressings to promote healing, and may be removed with less pain than conventional dressings.
Alginate may be used in a hydrogel consisting of microparticles or bulk gels combined with nerve growth factor in bioengineering research to stimulate brain tissue for possible regeneration. In research on bone reconstruction, alginate composites have favorable properties encouraging regeneration, such as improved porosity, cell proliferation, and mechanical strength, among other factors.
Alginic acid is a linear copolymer with homopolymeric blocks of (1→4)-linked β-D-mannuronate (M) and α-L-guluronate (G) residues, respectively, covalently linked together in different sequences or blocks. The monomers may appear in homopolymeric blocks of consecutive G-residues (G-blocks), consecutive M-residues (M-blocks) or alternating M and G-residues (MG-blocks). Note that α-L-guluronate is the C-5 epimer of β-D-mannuronate.
Alginate, a colloidal polyuronic acid structural molecule capable of gelation, is used in the preparation of colloidal biodegradable structures such as gels, biofilms, beads, nanoparticles, and microcapsules suitable for applications that range from gel based separation technologies to drug delivery and cell preservation.
Alginic acid sodium is a gelling and nontoxic anionic polysaccharide. The carboxylic acid groups on the alginic acid chain, renders it insoluble in water.However, converting alginic acid to its sodium form, enables it to solubilize in water easily.
Alginic acid sodium is used:
• in combination with chitosan, to fabricate a biodegradable porous scaffold for bone tissue engineering.
• to study the characteristics of a modified amphiphilic alginate derivative
• to the study the impact of alginate on the rate of lipid digestion by employing an in vitro digestion model
• in the preparation of alginate hydrogels
• as encapsulating agents of microparticles of β-galactosidae
Alginic acid, also referred to as algin or alginate, is a hydrophilic or anionic polysaccharide isolated from certain brown seaweed (Phacophycae) via alkaline extraction. It is present in cell walls of brown algae where it forms a viscous gel when binding with water. Alginic acid is a linear polymer consisted of L-glucuronic acid and D-mannuronic acid residues connected via 1,4-glycosidic linkages . Available in different types of salt, alginic acid has been used in a variety of uses in food, cosmetics and pharmaceu-tical products for over 100 years . Alginic acid is an FDA-approved food ingredient in soup and soup mixes as an emulsifier, thickener, and stabilizer . It is also available in oral dietary supplements and is found in antacids such as Gaviscon to inhibit gastroesophageal reflux by creating a physical barrier in presence of gastric acid . Alginate-based raft-forming formulations in the management of heartburn and gastric acid reflux have been used worldwide for over 30 years.
Once orally administered, alginic acid reacts with gastric acid to form a floating "raft" of alginic acid gel on the gastric acid pool. Alginate-based raft-forming formulations commonly contain sodium or bicarbonate; bicarbonate ions are converted to carbon dioxide in presence of gastric acid and get entrapped within the gel precipitate, converting it into a foam which floats on the surface of the gastric contents, much like a raft on water 4. The "raft" has a near neutral pH due to carbon dioxide and floats on the stomach contents and potentially functions as a barrier to impede gastroesophageal reflux 1,9. In severe cases, the raft itself may be refluxed into the oesophagus in preference to the stomach contents and exert a demulcent effect.
A straight chain, hydrophilic, colloidal polyuronic acidAlginic acid is used as a precursor for the preparation of sodium alginate, potassium alginate and calcium alginate, which finds application in various industries such as food, textile printing and pharmaceuticals. It acts as an additive in dehydrated products such as slimming aids. It is also used in the production of paper and textiles. It is actively involved in waterproofing, fireproofing fabrics. It is utilized as a thickening agent in drinks, ice cream and cosmetics. It plays an important role as a raw material for the synthesis of propylene glycol alginate and polysaccharide sulfate. It is also useful to treat and purify waste water having strong absorbility.
The absorption into the systemic circulation from oral formulations of alginic acid is reported to be minimal, as the mode of action of alginic acid is physical.
obable oral lethal dose reported in humans is above 15 g/kg . Ingestion of large quantities may result in abdominal distension, intestinal obstruction, nausea, vomiting, and difficulty swallowing. Aspiration or inhalation may lead to pneumonitis . In the event of overdosage symptomatic treatment should be given.
Alginic acid is not an antacid, but because of its unique mechanism of action, it is added to some antacid preparations to increase their effectiveness in the treatment and relief of the symptoms of GERD. In the presence of saliva, alginic acid reacts with sodium bicarbonate form sodium alginate. Gastric acid causes this alginate to precipitate, forming a foaming, viscous gel that floats on the surface of the gastric contents. This provides a relatively pH-neutral barrier during episodes of acid reflux and enhances the efficacy of drugs used to treat GERD. Alginic acid products are not indicated for the treatment of PUD.
Alginates are one of the most adaptable, multifaceted polysaccharides currently used in the development of various drug carriers. Alginates are sodium salts of alginic acid (a linear polymer that has d-mannuronic acid and l-guluronic acid residues in the polymer chain), which is obtained from brown seaweed. It is soluble in water and forms a thick gel-like system on hydration when present in divalent salt form, while it gets solubilizes in monovalent salt form. It has also been noted that the alginates with high guluronic acid form more viscous gel as compared with the others.
Reports are available showing that alginic acid and its salt with sodium and calcium are nontoxic and biocompatible in nature, and that it is widely being used in the food, cosmetic, and pharmaceutical industries. Traditionally this material is used as a binder or suspending agent but in recent decades these polymers have emerged as a potential tool for developing a different type of controlled, sustained, and targeted drug delivery for various therapeutics and biologics.
Alginates are polysaccharides produced by a wide variety of brown seaweeds (Laminaria sp., Macrocystis sp., Lessonia sp., etc.). Additionally, bacteria also synthesize alginates and these can be used as tools to tailor alginate production, by understanding the biosynthesis of the polymer in these bacteria. A family of enzymes termed mannuronan-C5-epimerases convert M into G at the polymer level. By genetically selecting and engineering Pseudomonas strains that contain only a single epimerase for the production of high G containing alginates has been possible. Using such strategies, alginates with up to 90% G content and extremely long G blocks have been produced.
Though such strategies are useful to engineer alginates, most of the alginates extracted for large-scale applications originate from natural sources such as seaweeds. The quality is determined by the species and even the seasonal variations. The alginate could contain from 10% to 70% G. Techniques of separation such as fractionation and precipitation in calcium can help separate the G block- and M block-rich alginates. The molecular weight of alginate is a critical factor to influence its viscosity in solution, besides the concentration of the polymer. The most important property of alginate is its ability to gel in the presence of cations (like Ca2 + and Ba2 +). The carboxylic acid groups of sugars in G blocks of adjacent polymer chains cross-link with multivalent cations to form a gel. Factors that influence the stiffness of the gel are molecular weight distribution of the alginate polymer (dependent on M/G ratio) and the stoichiometry of alginate with the chelating cation.
Alginic acid reduces reflux via its floating, foaming, and viscous properties . Alginic acid precipitates upon contact with gastric acid to create a mechanical barrier, or a "raft", that displaces the postprandial acid pocket . The formation of a raft is thought to occur rapidly, often within a few seconds of dosing. In clinical trials, alginic acid was effective in reducing the symptoms of gastroesophageal reflux disease. In healthy volunteers, alginic acid in combination with an antacid was effective in decreasing postprandial reflux in the upright position . Alginic acid is able to bind to cations when ingested.
The present opinion deals with the re-evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400–E 404) when used as food additives.
Alginic acid and its salts (E 400–E 404) are authorised as a food additive in the European Union (EU) in accordance with Annex II and Annex III to Regulation (EC) No 1333/2008 on food additives.
Alginic acid (E 400) is a linear glycuronoglycan polymer consisting mainly of β-(1→4)-linked d-mannuronic and α-(1→4)-linked l-guluronic acid units extracted from natural strains of various species of brown seaweeds (Phaeophyceae). Sodium (E 401), potassium (E 402), ammonium (E 403) and calcium alginates (E 404) are sodium, potassium, ammonium and calcium salts of alginic acid, respectively.
The Panel noted that, due to the possible hypersensitivity issues, limits for protein should be reduced as much as possible and included in the EC specifications.
The in vitro degradation by microbiota from human colon and the in vivo metabolism of alginic acid and its salts in animals have been investigated. These studies demonstrated that the in vivo biological fate of alginic acid and its salts are similar. Alginic acid and its salts would not be absorbed intact regardless of the form administered; they would not be metabolised by enzymes present in the gastrointestinal tract. However, they would be partially fermented during their passage through the large intestine by the action of the intestinal microbiota. The rate of breakdown in the gastrointestinal tract in humans is unknown.
No adverse effects were observed in short-term and subchronic toxicity studies in rats and in one subchronic study in dogs. In the rat studies, the caecal enlargement described by the authors was considered by the Panel as an adaptive process related to the high doses tested.
In human studies, the oral intake of sodium alginate was well tolerated. The Panel also noted that for the medicinal use of a combination of sodium alginate and magnesium alginate in infants and young children with a maximum daily dosage ranging from 417 to 834 mg/kg bw calculated as sodium alginate, constipation, diarrhoea, intestinal obstruction, flatulence, abdominal distension and bezoar are indicated as adverse effects. However, in a multicentre study in infants, no significant differences in the incidences of gastrointestinal adverse events between the groups treated with the combination of sodium alginate and magnesium alginate or with placebo were observed.
Alginic acid and its salts (E 400–E 404) are authorised in a wide range of foods. The Panel did not identify brand loyalty to a specific food category, and therefore, the Panel considered that the non-brand-loyal scenario covering the general population was the more appropriate and realistic scenario for risk characterisation because it is assumed that the population would probably be exposed over the long term to the food additive present at the mean reported use in processed food.
The refined estimates are based on 23 out of 75 food categories in which alginic acid and its salts (E 400–E 404) are authorised. The Panel considered that the uncertainties identified would, in general, result in an overestimation of the exposure to alginic acid and its salts (E 400–E 404) as a food additive in European countries for the refined scenario if it is considered that the food additive may not be used in food categories for which no usage data have been provided.
The Panel also noted that the refined exposure estimates are based on information provided on the reported level of use of alginates (E 400–E 404). If actual practice changes, this refined estimates may no longer be representative and should be updated.
Alginic acid is a natural polysaccharide, which has been widely concerned and applied due to its excellent water solubility, film formation, biodegradability and biocompatibility. This paper briefly describes the source, properties, structure and application of sodium alginate by summarizing and analyzing the current literature. This paper reviews the application of sodium alginate in the fields of food industry, catalyst, health, water treatment, packaging, immobilized cells, and looks forward to its application prospects.
Alginic acid found in the walls of brown seaweeds (Phaeophyceae) consists of D-mannuronic acid units and L-guluronic acid units probably linked β (1->4). The chains contain three distinct regions; in one, the D-mannuronic acid units alternate with L-guluronic acid units, whereas the remaining regions are homogeneous and contain either D-mannuronic acid or L-guluronic acid. The lengths and proportions of the three regions vary with the seaweed species and are responsible for the differences in chemical and physical properties of the various alginates.
Alginic acid is biosynthesised from GDP-D-mannuronic acid and GDP-guluronic acid. It seems probable that guluronic acid is derived from its isomer, mannuronic acid, the re action being catalysed by an epimerase.
Monovalent salts of alginic acid are soluble in water, but polyvalent salts are either insoluble or form gels. Solutions of alginates are very viscous due to the high molecular weight and random-coil formation of the polymers. The jellying and thickening properties of alginates are widely used commercially in foodstuffs, etc.
Alginic acid is widely used in food products and topical and oral pharmaceutical formulations. It is generally regarded as a nontoxic and nonirritant material, although excessive oral consumption may be harmful. Inhalation of alginate dust may be an irritant and has been associated with industrially related asthma in workers involved in alginate production. However, it appears that the cases of asthma were linked to exposure to unprocessed seaweed dust rather than pure alginate dust. An acceptable daily intake of alginic acid and its ammonium, calcium, potassium, and sodium salts was not set by the WHO because the quantities used, and the background levels in food, did not represent a hazard to health.
Alginic acid hydrolyzes slowly at warm temperatures producing a material with a lower molecular weight and lower dispersion viscosity.
Alginic acid dispersions are susceptible to microbial spoilage on storage, which may result in some depolymerization and hence a decrease in viscosity. Dispersions should therefore be preserved with an antimicrobial preservative such as benzoic acid; potassium sorbate; sodium benzoate; sorbic acid; or paraben. Concentrations of 0.1–0.2% are usually used.
Alginic acid dispersions may be sterilized by autoclaving or filtration through a 0.22 μm filter. Autoclaving may result in a decrease in viscosity which can vary depending upon the nature of any other substances present.
Alginic acid should be stored in a well-closed container in a cool, dry place.
Incompatible with strong oxidizing agents; alginic acid forms insoluble salts in the presence of alkaline earth metals and group III metals with the exception of magnesium.
Most favorable properties of alginate are its biocompatibility, low toxicity, relatively low cost, and mild and easy gelation. Alginates in the presence of divalent cations (mostly calcium cations) very quickly form a hydrogel, polymeric networks with three-dimensional configuration, capable of imbibing high amounts of water. This book discusses the chemical structure, the uses, and health benefits of alginic acid.
