Structural characterization of a galactomannan from the cyanolichen Leptogium azureum

• Published in: Carbohydrate polymers Vol. 53; no. 4; pp. 469 - 473
• Main Authors: Carbonero, E.R, Tischer, C.A, Cosentino, C, Gorin, P.A.J, Iacomini, M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2003; Elsevier Science
• Subjects: Applied sciences; Cyanolichen; Exact sciences and technology; Galactomannan; Leptogium azureum; Natural polymers; Physicochemistry of polymers; Starch and polysaccharides; Leptogium azureum; Cyanolichen; Galactomannan; Molecular structure; Oside polymer; Lichenes; Experimental study; Solvent extraction; Thallophyta; Leptogium azureum: Cyanolichen
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/S0144-8617(03)00148-6

A galactomannan was isolated from the cyanolichen Leptogium azureum via successive alkaline extraction and precipitation with Fehling solution. The structure of the polysaccharide was investigated using NMR spectroscopy, methylation analysis, Smith degradation, and HPSEC-MALLS. As galactomannans from other lichens species, the polymer obtained presents a (1→6)-linked main chain of α-mannopyranose, substituted preferentially at O-2 by α-Man p or β-Gal p non-reducing ends. As observed in previous investigations, the C-1 region of the 13C-NMR of these heteropolysaccharides are typical of some lichens species, and can be used as fingerprints in chemotaxonomy. However, in despite of the general structure in common, the substitution level of this structure and their content of mannose is higher than of the others galactomannans obtained of lichenized fungi contained the green alga of the genus Trebouxia.