Polysaccharides from the fruit bodies of the basidiomycete Laetiporus sulphureus (Bull.: Fr.) Murr

The two main polysaccharides from the basidiomycetous fungus Laetiporus sulphureus were isolated, purified and characterized. The structural assignments were carried out using C-13, H-1, and 1H,(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-mannopyranbsyl-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 a-D-mannopyranosyl units are present in our fucomannogalactan of L. sulphureus. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.