Polysaccharide content and composition analysis in the herb <i>Astragalus albicaulis</i> DC

Abstract

Aim – to isolate and analyze the polysaccharides content in the herb Astragalus albicaulis.
 Material and methods. The object of the study was the herb Astragalus albicaulis harvested in the Kursk region in 2022 during the period of mass flowering. To isolate the polysaccharide complex, polyphenolic compounds were previously removed from the raw material. After drying, a water-soluble polysaccharide complex, pectin substances, hemicellulose A and hemicellulose B were sequentially isolated from the extraction cake. As extractants, purified water was used to isolate the water-soluble polysaccharide complex, a mixture of 0.5% solutions of oxalic acid and ammonium oxalate (1:1) was used for pectin substances extraction, to obtain hemicelluloses – a 10% aqueous solution of alkali followed by neutralization with acetic acid. The composition of the obtained substances was analyzed after acid hydrolysis using paper chromatography.
 Results. It was found that the yield of water-soluble polysaccharides from the herb Astragalus albicaulis was 9.41% ± 0.46%, pectin substances – 17.49% ± 0.62%, hemicellulose A – 0.86% ± 0.04%, hemicellulose B – 5.36% ± 0.25%. After acid hydrolysis, 5 monosaccharides were found in the complex of water-soluble polysaccharides: rhamnose, xylose, arabinose, galactose, and glucuronic acid, of which arabinose and galactose were predominant. The monosaccharide composition of pectin substances was represented by xylose, arabinose, glucose, galactose and galacturonic acid, galacturonic acid predominated. As a result of the identification of hydrolysis products of hemicellulose A and B, rhamnose, xylose and glucose were found, the predominant monosaccharide was xylose.
 Conclusion. For the first time, complexes of polysaccharides – water-soluble polysaccharides, pectin substances, hemicellulose A and B – were isolated and studied by fractions from the herb Astragalus albicaulis, their qualitative composition was registered. The data obtained indicates that the herb Astragalus albicaulis can be used as a source of natural polysaccharides.