The composition of water-soluble polysaccharides of Heracleum sosnowskyi stem callus cells
E.N. Gordina, A.A. Zlobin
Section: Chemistry of natural environments and objects
A fraction of water-soluble polysaccharides extracted from cells with hot water was isolated from the callus tissue of the stem of the Heracleum sosnowskyi Manden. It was shown that the main components of the carbohydrate chains of the water-soluble polysaccharides fraction of callus are galactose, arabinose, and glycuronic (D-galacturonic and D-glucuronic) acid residues, which were identified in almost equal amounts. Glucose, rhamnose, xylose, and mannose residues are also included as minor monosaccharides in callus. Using ultrafiltration and ion exchange chromatography methods, it was found that this polysaccharide fraction is represented by a heterogeneous mixture of acidic polysaccharides differing in monosaccharide composition. It is shown that its composition includes polysaccharides, which by the set of neutral monosaccharide residues correspond to the fractions of arabinogalactans, which are part of proteoglycans extracted from the plant with hot water. At the same time, they differ from native plant arabinogalactans in a higher content of arabinose and galactose residues, as well as lower amount of D-galacturonic and D-glucuronic acid residues. It was found that the fraction of water-soluble polysaccharides of callus includes acidic polysaccharides, which are close to the pectin polysaccharides fraction of protopectin complex of callus tissue cell walls in terms of the content of D-galacturonic acid residues and the ratio of neutral monosaccharide residues, the main carbohydrate chains of which contain extended regions of low-methylesterified 1,4- -D-galacturonan and rhamnogalacturonan-I, as well as the side carbohydrate chains represented by arabinan, galactan and/or arabinogalactan. It was revealed that polysaccharides included in the callus polysaccharide fraction contain significant amounts of protein compounds that probably form strong complexes with them or are covalently bound to their carbohydrate chains.
ISSN 1995-4301
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