Uronic Acid

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Related to Uronic acids: aldonic acids

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 ?
Hexosamine and uronic acid, commonly known as matrix molecules, are involved in the synthesis of new extracellular matrices.
The composition of monomeric sugars and uronic acids were determined using the National Renewable Energy Laboratory (NREL) protocol [10] and analyzed by the high-performance anion exchange chromatography (HPAEC) (Dionex, ICS-3000, USA) system on a CarboPac PA20 (Dionex, USA) according to the literature [11].
The contents of monosaccharides and uronic acids in the in the dietary fibre fractions from the kernels are presented in Table 3.
In this study, reed fibers were characterized chemically, to quantify the extractive content in the acetone (3.60%), total extractive content (11.94%), insoluble lignin content (22, 19%) and solubility in acid (2.70%), besides the total carbohydrate (55.89%) and uronic acid (1.85%) concentrations.
Band at 960 [cm.sup.-1] was related to stretching vibrations with contributions from deformation vibrations of the uronic acids residues in heteropolymeric blocks (Leal et al, 2008).
(In the glycolipids of the latter uronic acids were found).
The acidic and basic modifications of monosaccharides found in the extracellular matrix yield uronic acids (glucuronic acid) and amino sugars (hexosamines) and they form a vital part in many structural polysaccharides and glycosaminoglycans (GAG) found in the ECM.
The monosaccharide composition of Cf0 (mol%) is Fuc, 45.0, Xyl, 6.0, Man, 16.2%, Gal 18.0, Glc, 8.8, Uronic acids, and 6.0.
[14] proposed a method based on high-performance anion-exchange chromatography to simultaneously determine uronic acids including DGuA in some polyuronides.
The composition of neutral sugars and uronic acids and the molecular weights of the hemicellulosic samples were determined according to the literature [34].