Альгиновая кислота

Химические свойства

Alginic acid is a tasteless, practically odorless, white to yellowishwhite, fibrous powder.

Использование

algin (alginic acid) is used in cosmetic formulations as a thickener, stabilizer, and gelling agent. It is obtained from different varieties of brown seaweed.

Методы производства

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.

Определение

A polysaccharide composed of β,d-mannuronic acid residues linked so that the carboxyl group of each unit is free, while the aldehyde group is shielded by a glycosidic linkage. It is a linear polymer of the mannuronic acid in the pyranose ring form.

Фармацевтические приложения

Alginic acid is used in a variety of oral and topical pharmaceutical formulations. In tablet and capsule formulations, alginic acid is used as both a binder and disintegrating agent at concentrations of 1–5% w/w. Alginic acid is widely used as a thickening and suspending agent in a variety of pastes, creams, and gels; and as a stabilizing agent for oil-in-water emulsions.
Alginic acid has been used to improve the stability of levosimendan.
Therapeutically, alginic acid has been used as an antacid.In combination with an H2-receptor antagonist, it has also been utilized for the management of gastroesophageal reflux.

Профиль безопасности

Moderately toxic by intraperitoneal route. When heated to decomposition it emits acrid smoke and irritating fumes

Безопасность

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.
LD₅₀ (rat, IP): 1.6 g/kg

хранилище

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.

Методы очистки

To 5g of acid in 550mL water containing 2.8g KHCO3 are added 0.3mL of acetic acid and 5g potassium acetate. EtOH is added to make the solution to 25% (v/v) in EtOH, and any insoluble material is discarded. Further addition of EtOH, to 37% (v/v), precipitated alginic acid. Collect the acid and dry it in vacuo. [Pal & Schubert J Am Chem Soc 84 4384 1962.]

Несовместимости

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.

Регуляторный статус

GRAS listed. Accepted in Europe for use as a food additive. Included in the FDA Inactive Ingredients Database (ophthalmic preparations, oral capsules, and tablets). Included in the Canadian List of Acceptable Non-medicinal Ingredients. Included in nonparenteral medicines licensed in the UK.