Carbohydrate, glycopeptide and protein components of the lichen Sticta sp. and effect of storage
1993
Corradi da Silva, M. de L. | Iacomini, M. | Jablonski, E. | Gorin, P.A.J.
Three aldoses, six alditols, eight oligosaccharides, three polysaccharides and a glycopeptide were found in a Sticta sp. The most interesting of these were gentiobiose, -triose and -tetraose. O-alpha-D-Galp-(1 leads to 6)-O-beta-D-Galp-(1 leads to)-D-glyceritol released on alkaline treatment, and a polysaccharide with predominant (1 leads to 4)-linked beta-D-Xylp units. Present were a galactoglucomannan, a polysaccharide, possible a mixture, containing beta-D-Galf, and alpha-L-Araf units and a glycopeptide with alpha- and beta-D-Galf Galp, Glcp and Manp units, having a core with successive (1 leads to 2)-linked alpha-D-Manp residues substituted at O-3 with those of alpha-D-Galf. After four years storage of the lichen, the contents of the principal polyols, ribitol (0.86%), arabinitol (0.99%) and mannitol (2.50%) fell to practically zero, with the appearance of threitol (0.03), xylitol (0.01%) and myo-inositol (0.03%). Also, the protein content fell from 34 to 18%. The most abundant amino acids were valine (10.5% of total) in fresh lichen and threonine (14.6%) in stored lichen.
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