Abstract
The chemical composition (polyphenols) of the leaves of the Crataegus pontica K. Koch plant has been studied. The process of isolating polyphenols from plant raw materials includes several stages: extraction of raw materials, processing of the extract with organic solvents, evaporation, precipitation of the sum of polyphenols, purification. The increase in the efficiency of the use of raw materials is achieved mainly at the first stage – extraction. The yield of the sum of polyphenols was studied depending on: the composition of the extractant, the extraction modulus, the multiplicity of extraction, the ratio of raw materials – extractant, temperature, thickening conditions, treatment of the aqueous residue with organic solvents, the conditions of precipitation of the sum of polyphenols and their drying. As a result, optimal conditions for the isolation of polyphenols from plant raw materials were selected, and the found condition obtained the sum of polyphenols from the autumn leaves of pontic hawthorn with a yield of 4.5%. Chromatographic study of the isolated fractions revealed that the polyphenols of the ethyl acetate fraction are mainly represented by monomeric catechins, flavonolams and tannins. The sum of polyphenols from the ethyl acetate fraction was divided on a column with sephadex LH-20 using chloroform-methanol as an eluent in various ratios (10 : 1→3 : 1). The structures of the isolated compounds were determined using physicochemical methods. As a result, more than 12 polyphenols were isolated from the leaves of pontic hawthorn, such as quercetin-3-O-β-D-galactopyranoside (hyperoside), quercetin-3-rutinoside, 3,5,7,3',4'-pentaoxyflavone (quercetin), 2-(3,4-dimethoxyphenyl)-7methoxy-3,4-dihydro-2H-chromene-3,4,5,6-tetrol, aрigenin-6-C-glycoside, procyanidin B, (+)-catechin (5,7,3',4'-tetraoxyflavan-3-ol), (-)-epicatechin (5,7,3',4'-tetraoxyflavan-3-ol), ellagic acid, gallic acid, 1-O-galloyl-4-O-catechin-β-D-glucose and caffeic acid ester with 2,3-dihydroxyglutaric acid. Of these, the last two substances were first isolated from this plant.
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