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From the roots of the medicinal plant Althaea officinalis L., three D-glucans were isolated by gel chromatography which differed in molecular weights. The results of methylation analyses and 13C NMR measurements indicated predominantly linear character of the polysaccharide chains composed of α-D-glucopyranose units linked by 1 → 6 glycosidic bonds almost exclusively. The polymers had essentially the same structural features as D-glucan isolated from the leaves of this plant.

Homogeneous, water soluble 4-O-methyl-D-glucurono-D-xylan was isolated from the bark of white willow (Salix alba L.). The equivalent weight of the polymer was found to be 990, i.e. each sixth unit of D-xylose on average was substituted by 4-O-methyl-D-glucuronic acid. The single-ion activity coefficient of calcium counterions γCa2+ was estimated in a molecular disperse solution of calcium 4-O-methyl-D-glucurono-D-xylan. The mean distance of adjacent carboxyl groups, b = 1.1 nm, was obtained from the experimentally determined value γCa2+ = 0.39 using the relation γCa2+ = f(b). Comparison of the value b = 1.1 nm with the D-xylose unit length (0.50 nm) and the calculated value of the equivalent weight indicated the presence of blocks with a close arrangement of uronic acids in the D-xylan chain. In this case, as it follows from the conformation of the macromolecule, at least each second D-xylose on average bears the side monomeric 4-O-methyl-α-D-glucuronic acid unit at C(2). Blocks with a high concentration of uronic acid alternate with approximately three times greater blocks of unsubstituted, or very little substituted D-xylose units.

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