Comparative studies on the polysaccharides of Cladonia alpestris (reindeer moss), Cladonia confusa,and Cladonia amaurocraea

The chemical structures of polysaccharide components of three species of the lichen genus Cladonia were compared. C. alpestris and C. confusa are similar in overall growth appearance despite different habitats, and each contains traces of water-insoluble nigeran. The residual lichens gave almost pure d-galacto-d-mannans isolated via insoluble Cu complexes formed with Fehling solution. They were not identical but structurally related having (1→6)-linked α-d-mannopyranosyl main-chains substituted in different patterns by β-d-galacto- and α-d-mannopyranosyl groups. Supernatant solutions of the Fehling-solution precipitation contained high proportions of β-d-galactofuranosyl residues. The polysaccharide of C. alpestris contained consecutive (1→2)-linked α-d-mannopyranosyl units substituted in the 6-position by β-d-galactofuranose, whereas that of C. confusa was a d-galactan with both pyranosyl and furanosyl forms. The d-glucan component of C. amaurocraea was isolated together with d-galacto-d-mannan as insoluble Cu complexes. The former was isolated in good yield and proved to be water-insoluble pustulan. The galactomannan had the same overall structure as those of C. alpestris and C. confusa, but showed differences according to the ¹³C-n.m.r. spectra.