Development of a Technique for Obtaining Polysaccharides from Leaves of the Birch (Betula pendula Roth. and Betula pubescens Ehrh.)

Abstract: The goal of the study was to develop a complex technique for the extraction and purification of polysaccharides from the leaves of birch (Betula pendula Roth., Betula pubescens Ehrh., family Betulaceae) (PSfB). The following characteristics have been used as criteria for estimating the effect of the parameters studied on the production of target compounds: the yield of PSfB (the gravimetric method), the protein content (spectrophotometry), the molecular weight distribution (high performance size-exclusion chromatography), and the degree of purification from low-molecular-weight impurities (LMWI). The following optimal parameters have been determined in experiments at different stages of PSfB production: the degree of grinding of a raw material 1.2–3 mm; the pH value of the extractant (purified water with the pH value of 6.5–7.0); the raw material : extractant ratio 1 : 20; the extraction temperature 50°C; the temperature and the degree of evaporation 50°C, four times; the concentrate : ethanol ratio 1 : 3; and the method of purification from LMWI by ultrafiltration. As a result of the work, an optimized method for obtaining PSfB has been developed, which affords a high yield without the loss of quality of the product (minimal admissible content of LMWI with the maximum content of high-molecular-weight fractions). The method is the basis for the development of laboratory regulations for obtaining an active pharmaceutical substance based on polysaccharides from birch leaves.