The structure and prebiotic activity of arabinogalactan from Ferula Kuhistаnica.

Acidic arabinogalactan with molecular weight 36 kDa was isolated from the aerial part of Ferula kuhistаnica, the monosaccharide composition of which is represented by galactose and arabinose in a ratio of 3.6:1. The chemical and spectral methods revealed a main polymer chain consisting of (1 â†’ 6) ß-galactopyranose residues, where in position of C-3 were the residues of α-arabinofuranose and its 1,5-linked oligomers, as well as ß-GlcpA-4-OMe-(1 â†’ 6)-ß-Galp-(1→ fragments. In addition, a small part of the main chain carries monosaccharide residues of ß-Galp-(1→ in position C-2. The effect of arabinogalactan on the growth of an associative culture of bifidobacteria and some mono-strains of lactobacilli was studied and it was shown that it exhibits more effective prebiotic activity.

Structure of arabinogalactan and pectin from the Silybum marianum.

From the leaves of Silybum marianum L. were isolated arabinogalactan with molecular weight 38 kDa and pectic substances. The monosaccharide composition of arabinogalactan was represented by ß-galactose and α-arabinose in a ratio of 2.6:1.0 and ß-galacturonic acid as a minor component. By chemical methods and GC, GC-MS, 1D and 2D NMR spectroscopy was established that the arabinogalactan consists of d-galactopyranose residues linked by ß-1,6-glycosidic bonds as a main chain, and the side chain was represented by α-arabinose, ß-galactose and 4-O-methylglucuronic acid. Pectic substance was found in small amounts. According to NMR data it contains also a branched rhamnogalacturonan.