Alginic acid

Alginic acid

Names
Other names Alginic acid; E400; [D-ManA(β1→4)L-GulA(α1→4)]n
Identifiers
CAS Number	9005-32-7 Y
ChemSpider	None
ECHA InfoCard	100.029.697
EC Number	232-680-1
E number	E400 (thickeners, ...)
UNII	8C3Z4148WZ N
CompTox Dashboard (EPA)	DTXSID601010868
Properties
Chemical formula	(C6H8O6)n
Molar mass	10,000 – 600,000
Appearance	White to yellow, fibrous powder
Density	1.601 g/cm3
Acidity (pKa)	1.5–3.5
Pharmacology
ATC code	A02BX13 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Alginic acid, also called algin, is a naturally occurring, edible polysaccharide found in brown algae. It is hydrophilic and forms a viscous gum when hydrated. When the alginic acid binds with sodium and calcium ions, the resulting 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.^[1] The biofilm and P. aeruginosa have a high resistance to antibiotics,^[2] but are susceptible to inhibition by macrophages.^[3]

Alginate was discovered by British chemical scientist E. C. C. Stanford in 1881, and he patented an extraction process for it in the same year.^[4] The alginate was extracted, in the original patent, by first soaking the algae in water or diluted acid, then extracting the alginate by soaking it in sodium carbonate, and finally precipitating the alginate from solution.^{[5][better source needed]}