An unusual juxtaposition of polysaccharide components of Collema leptosporum |
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Authors: | S R T Prado P A J Gorin P M Stuelp N K Honda M Iacomini |
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Institution: | a Depto de Bioquímica, Universidade Federal do Paraná, C.P. 19046, 81531-990, Curitiba-PR, Brazil b Depto de Química, Universidade Federal do Mato Grosso do Sul, 79070-900, Campo Grande-MS, Brazil |
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Abstract: | The lichenised ascomycete, Collema leptosporum Malme, was extracted with aqueous methanol to give traces of mannitol and 3-O-β-
-glucopyranosyl-
-mannitol (2.7% yield). The residue was consecutively extracted with hot water to give a complex uronic acid-containing polysaccharide, and then with hot aqueous alkali which provided a mixture of polysaccharides. This was fractionated with Cetavlon to give a branched galactomannan, which had the lowest content of galactose yet reported for such a lichen polysaccharide. It has a main chain of (1→6)-linked -Manp units partly substituted at O-2,4 by non-reducing end-units of Manp and Galp, shown by NMR spectroscopy to have - and β-configurations, respectively. The other polysaccharide component was unexpectedly a branched (1→3), (1→6)-linked β-glucan, which is typical of a basidiomycete, whereas those of ascomycetes contain similar linkages but in linear glucans. |
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Keywords: | Lichenised ascomycetes Collema leptosporum Galactomannan Branched glucans |
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