RESUMO
The two main polysaccharides from the basidiomycetous fungus Laetiporus sulphureus were isolated, purified and characterized. The structural assignments were carried out using (13)C, (1)H, and (1)H,(13) HSQC nuclear magnetic resonance spectroscopy, methylation analysis, and Smith degradation. One was a linear beta-glucan having a (1-->3)-linked main chain, namely laminaran. The other was a fucomannogalactan, which consisted of a main chain of (1-->6)-linked alpha-D-galactopyranosyl residues, a part of them being substituted at O-2 by 3-O-D-mannopyranosyl-L-fucopyranosyl, alpha-D-mannopyranosyl and in a minor proportion, alpha-L-fucopyranosyl groups. This heteropolysaccharide is related to those of other Basidiomycetes heterogalactans, although it differs distinctly in its side-chain structures. Whereas part of the single-unit L-fucopyranosyl and/or 3-O-alpha-mannopyranosyl-L-fucopyranosyl residues are present as side chains of the other heterogalactans, additional alpha-D-mannopyranosyl units are present in our fucomannogalactan of L. sulphureus.
Assuntos
Galactanos/análise , Glucanos/análise , Polyporales/química , Sequência de Carboidratos , Galactanos/química , Galactanos/isolamento & purificação , Glucanos/isolamento & purificação , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Polyporales/crescimento & desenvolvimentoRESUMO
The partially 3-O-methylated mannogalactans were isolated from the fruiting bodies of edible basidiomycetes Pleurotus ostreatus 'florida' Berk. and Pleurotus ostreatoroseus Sing. They were obtained via successive aqueous extraction, freeze thawing, and precipitation with Fehling solution and then investigated using (13)C- and (1)H-nuclear magnetic resonance spectroscopy (including COSY, TOCSY and HMQC techniques), methylation analysis and Smith degradation. The main chain consisted of (1-->6)-linked alpha-D-galactopyranosyl residues containing 3-O-Me-alpha-D-galactopyranoses, a part of these units being substituted in the position O-2 with beta-D-mannopyranose residues. The heteropolysaccharides found were similar with differences only in the levels of the 3-O-Me-alpha-D-galactopyranoses residues. The presence of partially 3-O-methylated mannogalactan appears to be typical of Pleurotus spp.
Assuntos
Galactanos/análise , Mananas/análise , Pleurotus/química , Pleurotus/crescimento & desenvolvimento , Configuração de Carboidratos , Sequência de Carboidratos , Espectroscopia de Ressonância Magnética , Metilação , Dados de Sequência MolecularRESUMO
The two main water-soluble extracellular polysaccharides produced by the basidiomycete fungus Pleurotus ostreatoroseus Sing were isolated and purified. They were characterized using 13C, 1H, and 1H, 13C HMQC NMR spectroscopy, methylation analysis, and Smith degradation. One was a mannan having a main chain of (1-->6)-linked alpha-D-mannopyranosyl residues, almost all of which were branched at O-2 with side chains of different lengths, containing 2-O- and 3-O-linked mannopyranosyl units. The other was a partially 3-O-methylated (1-->4)-linked alpha-D-galactopyranan, a structure that has not been previously described.