Abstract
Extraction of Dictyonema glabratum with hot 2% (w/v) aqueous KOH at 100°C, followed by neutralisation and freeze-thawing, gave an insoluble glucan. The residue was further extracted by a similar process, but with hot 10% (w/v) aqueous KOH, furnishing a mixture of glucan, mannan and xylan. The mannan and xylan were obtained via precipitation of its copper complex with Fehling’s solution, leaving the glucan in the supernatant. The insoluble complex was finally purified through gel permeation chromatography. Methylation analysis, one- and two-dimensional nuclear magnetic resonance examination showed the polysaccharides to be a (1→3)-linked α-glucan (pseudonigeran) and a (1→4)-linked β-xylan, both not previously encountered in lichens, and a newly discovered (1→6)-linked β-mannan.
Published Version
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