Uronic Acid


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Related to Uronic Acid: hyaluronic acid, Aldonic acid

uronic acid

[yə′rän·ik ′as·əd]
(organic chemistry)
One of the compounds that are similar to sugars, except that the terminal carbon has been oxidized from the alcohol to a carboxyl group; for example, galacturonic acid and glucuronic acid.

Uronic Acid

 

any of the organic substances that are related to monosaccharides but that are distinguished from the latter by having a carboxyl group (—COOH) in place of the—CH2OH radical. The difference is illustrated by the following structural formulas:

Uronic acids are crystalline or amorphous substances that are nonvolatile, relatively high-melting, and readily soluble in water and polar solvents. Chemically, they possess the properties of both monosaccharides (mutarotation, oxidation, reduction, ability to form glycosides) and hydroxy acids (formulation of esters and lactones). Uronic acids occur in nature with six carbon atoms, and their names are based on the corresponding hexose. The name “glucuronic acid,” for example, derives from “glucose.”

Uronic acids are constituents of many important biopolymers of plant and animal origin. D-glucuronic acid is a component of hemicelluloses, gums, hyaluronic acid, and heparin; D-galacturonic acid, which is the monomeric unit of pectic substances, is a constituent of certain bacterial polysaccharides. The biosynthesis of uronic acids occurs with the participation of nucleoside diphosphate sugars and involves the oxidation of the—CH2OH radical of the monosaccharide. In animals, D-glucuronic acid (found in the blood and urine) removes toxic substances by forming glycosides; the acid is also the starting material in the biosynthesis of absorbic acid.

REFERENCE

Khimiia uglevodov. Moscow, 1967. Chapter 10.

L. V. BAKINOVSKII

References in periodicals archive ?
Total non-cellulosic polysaccharides (NCP) = rhamnose + fucose + arabinose + xylose + mannose + galactose + glucose + uronic acids
Uronic acid content of the antler was determined by the method of Scott (1960) and Kosakaki and Yosizawa (1979).
Determination of the effect of [beta]-carotene on the inhibition of lung uronic acid content
All the fraction were composed mainly of neutral sugar, and did not contain significant amount of uronic acid and protein (data not shown).
4] indicated the presence of approximately 9% uronic acid in the extractable polysaccharide fraction.
A lesser polymer is hemicellulose, a complex polymer consisting of various hexose and pentose sugars, together with acetyl groups, and uronic acids.
Many methods exist for analytical determination of uronic acids in alginates [6], but statistical arrangement of uronate residue blocks in the macromolecules is studied chiefly by methods of NMR [7, 8].
Main monosaccharide residues were glucose (ca 55%), galactose (ca 23%), arabinose (ca 12%) and uronic acids (ca 6%), whereas mannose, rhamnose, fucose and xylose were contained only in minor amounts below 3% each.
Fischer, "Ion-Pair RP-HPLC Determination of Sugars, Aminosugars and Uronic Acids after Derivatization with p-Aminobenzoic Acid," Anal.