The study of the polysaccharide composition of the herb of Alchemilla L. genus species growing in the territory of the Precarpathian region

Medicines of plant origin containing polysaccharides are used in pharmaceutical practice since they exhibit a wide spectrum of thepharmacological activity. Species of the Alchemilla L. genus of the Rosaceae family are of important scientific and practical importance; they contain different groups of biologically active substances (BAS), including phenolic compounds and polysaccharides. The lack of information in the literature on the quantitative content of polysaccharides in this raw material indicates the topicality of research in this direction. Aim. To isolate and study the polysaccharide composition of the herb of the Alchemilla L. genus species growing in the territory of the Precarpathian region. Materials and methods. To isolate polysaccharide fractions and study their monomer composition, we used herb of 6 species of the Alchemilla L. genus (Alchemilla (A.) flabellata Buser., A. subcrenata Buser., A. phegophila Juz., A. microdonta Juz., A. hebescens Juz., A. turkulensis Pawі.) harvested during the mass flowering phase in various areas of the Ivano-Frankivsk region within 2020-2021. The quantitative content of polysaccharide fractions in the raw material studied was determined by the gravimetric method after successive extraction of the raw material with purified water R, hydrochloric acid solution and sodium hydroxide solution, followed by precipitation with 96 % ethanol R. The qualitative monomer composition of polysaccharides was determined by the ascending paper chromatography(PC) and thin-layer chromatography (TLC) in different solvent systems compared to authentic samples of neutral and acidic monosaccharides. Results and discussion. It was found that the total content of polysaccharide fractions in the herb of the Alchemilla species studied ranged from 7.73 % to 15.35 %, depending on the type of Alchemilla species. The yield of water-soluble polysaccharides (WSP) ranged from 2.62 % to 5.49 %, pectin substances (PS) – from 1.41 % to 2.13 %, hemicellulose (HC) A – from 0.45 % to 2.96 % and HC B – from 2.51 % to 6.44 %. The maximum amount of WSP and HC A was observed in the herb of Alchemilla turkulensis Pawł. (5.49 % and 2.96 %, respectively), the highest amount of PS and HC B was detected in the herb of Alchemilla phegophila Juz. (2.13 % and 6.44 %, respectively). The composition of monosaccharides was determined by the methods of PC and TLC compared to authentic samples. Glucose and arabinose were identified in the hydrolysates of the WSP of the herb of the Alchemilla L. genus species. The monomer composition of PS of the raw material studied was represented by glucose, arabinose and galactose. Glucose, galactose and xylose were found in the hydrolyzates of HC A fraction; glucose, galactose, arabinose, xylene, rhamnose, glucuronic and galacturonic acids were identified in HC B fraction. Conclusions. For the first time, polysaccharide complexes have been isolated from 6 species of the Alchemilla L. genus harvested in different areas of the Ivano-Frankivsk region. The monomer composition of sugars has been determinedby the methods of PC and TLC compared to authentic samples of monosaccharides in the hydrolyzates of WSP, PS, HC A and B fractions of species of the Alchemilla L. genus growing in the territory of Precarpathian region. The research results obtained are of practical importance for the further study of the pharmacological activity of the raw material studied and can be used in the development of quality control methods for the medicinal plant raw material and substances obtained from it.