Glycuronic acid

Animal polysaccharides containing D-glucuronic acid include heparan sulfate,108 chondroitin 4- and 6-sulfates,109 and hyaluronic acid.109 

Among the plant polysaccharides there may be mentioned the hemi-celluloses the most common of these contain 4-O-methyl-D-glucuronic acid as branch units linked to a /3-D-xylan backbone.110 The commercially important gum arabic, a soluble polysaccharide produced by Acacia trees and widely used in foods and pharmaceuticals, also contains glucuronic units.111 D-Glucuronic acid has been found in sulfated complex polysaccharides from brown algae.112 

The acid also occurs in many flavonol glycosides of plants, and a-linked to a glycerol unit, it has been found as a constituent of ardisicrenoside E, a triterpenoid pentasaccharide from Ardisia crenata.113 

Glucuronic acid is also constituent of pathogenic bacteria. The simplest structure for a pneumococcal capsular polysaccharide has the repeating unit [- 4)-/3-d-G1c-(1 3)-/3-D-GlcpA-(l ]ra.120 

Microbial polysaccharides may contain substituted glucuronic acids. 4-0-(L-l-Carboxyethyl)-D-glucuronic acid has been identified121 as component of the capsular polysaccharide from Klebsiella type 37, and 3-0-(l-1-carboxyethyl)-D-glucuronic acid has been found in the exopolysaccharide produced by Altermonas sp. 1644.122 

---

Supplement (combined with Volume IV) 1942 195-449 Carbonyl-carboxylic acids Glyoxalic acid, 504. Acetoacotic acid, 630. Hydroxy-carbonyl carboxylic acids Glycuronic acid, 883. 

A polysaccharide (glycan) composed entirely of glycuronic acid residues is named byreplacing -icacid by -an . The generic name for this group of polysaccharides is glycuronan . 

The acidic sugars discussed in this Section are glycuronic acids and glycu-losonic acids. Bacterial polysaccharides may also become acidic by substitution of sugar residues, for example by etherification with lactic acid, acetala-tion with pyruvic acid, or phosphorylation, and these possibilities will be discussed in the following Sections. A sugar that does not fall into any of... 

The capsular polysaccharide from Rhizobium meliloti IFO 13336 contains terminal ct-D-ribofuranosyluronic groups (19). With this obvious exception, all known glycuronic acids in bacterial polysaccharides are py-ranosidic. 

In several polysaccharides containing glycuronic acid residues, the carboxyl groups of these are linked to the amino group of amino compounds, forming amides. In the simplest examples, these are primary amides, such as the 2-formamido- and 2-acetamido-2-deoxy-D-galacturonamide (49) residues in 0-specific polysaccharides from different strains of Pseudomonas... 

The c.d. spectra of glycuronic acids have been measured in a number of laboratories. " These sugar derivatives, named after the corresponding aldohexose, have the exocyclic hydroxymethyl group on C-5 replaced by the carboxyl chromophore. The structure of /3-D-mannopyranuronic acid is given as an example in formula 9, and the structures of the parent compounds in Fig. 1. 

Martens, D.A. and Frankenberger, Jr., W. T., Determination of glycuronic acids by high-performance anion chromatography with pulsed amperometric detection, Chromatographia, 30, 651, 1990. 

The identification of L-iduronic acid as the major glycuronic acid constituent of heparin proved to be a much slower process than the identification of the amino sugar residue. Although this compound was detected in acid hydrolyzates of heparin116117 and heparin oligosaccharides,118 its yield was usually poor, because of the drastic conditions used for the acid hydrolysis (which are known to lead to extensive destruction of uronic acid).119120 Also, L-iduronic acid escaped detection as L-idose in the hydrolyzates of carboxyl-reduced heparin, probably because L-idose is readily converted into 1,6-anhydro-L-idose under the usual hydrolytic conditions. 

Della Pietra G, Illiano G, Soscia M. 1967. Glycuronic acid and glycuronamide detoxicating activity. Biochem Pharmacol 16 1571-1573. 

Little information is available on the decarboxylation of glycuronic acids, other than from those derived from hexoses. Machida103 reported that both D-xyluronic acid and D-arabinuronic acid undergo decarboxylation in boiling, 12% hydrochloric acid, but the yields of... 

In this Section, deoxy sugars, aminodeoxy sugars, and glycuronic acids are treated as modification products of simple aldoses that are classified here according to the structure of their formal, carbohydrate precursors. 

The final stages of the biosynthetic process may include transfer of a polysaccharide chain from an intermediate acceptor to a final acceptor, or liberation of the free polysaccharide. Monosaccharide residues included in a polymeric chain may be subjected to further enzymic modifications, such as incorporation of O-linked substituents (see Section III,6) or the epimeri-zation at C-5 of glycuronic acid residues mentioned in Section 111,1,c. 

---