ISOLATION AND STUDY OF THE COMPOSITION OF PROANTHOCYANIDINS FROM INNER BARK OF BIRCH BETULA PENDULA ROTH

A comparative analysis of the yields of proanthocyanidins isolated from the initial and deresinated (extracted with hexane) birch inner bark (Betula pendula Roth) with water, 15% water-ethanol solution and ethyl acetate in a Soxhlet apparatus was carried out. It was shown that preliminary extraction of birch inner bark with hexane has no significant effect on the yield of proanthocyanidins during its subsequent extraction with water, 15% water-alcohol solution and extraction with ethyl acetate in a Soxhlet apparatus. The average yield of proanthocyanidins from the initial and deresinified birch inner bark during extraction with water was 1.20 and 1.21%; with 15% water-alcohol solution – 1.44 and 1.46%; and with ethyl acetate in Soxhlet apparatus – 1.46 and 1.60%, respectively. The composition of proanthocyanidins isolated with 15% aqueous-alcoholic solution and ethyl acetate in a Soxhlet apparatus was studied by UV, FTIR and 13C NMR spectroscopy methods. It was shown that the composition of the obtained proanthocyanidins contains a galloyl group, which increases the antiradical activity of the obtained substances. After transformation of proanthocyanidins into colored anthocyanidins, the flavonoid composition of the obtained substances was studied. By converting proanthocyanidins into colored anthocyanidins the flavonoid composition of the obtained substances was studied. It was found, that proanthocyanidins in birch inner bark mainly consist of procyanidin and prodelphinidin.