Heteropolysaccharides of the lichen Evernia prunastri.

Extraction of Evernia prunastri with hot aqueous alkali solubilized heteropolysaccharide-containing material which was purified via Fehling precipitation. Further workup of this polysaccharide with Cetavlon gave two fractions having related but different structures. Each structure consisted of a 1-->6-linked alpha-D-Man p main chain partially monosubstituted at O-2 with side chains of alpha-D-Gal p and partially disubstituted at O-2 and O-4 with alpha-D-Gal p and beta-D-Gal p, respectively. The fractions differed in that one contained much more uronic acid than the other, with corresponding predominance of side chains containing alpha-D-Glc pA-(1-->3)-D-Glc p, alpha-D-Gal p-(1-->2)-D-Glc p, and beta-D-Gal f units.