Siberian Federal University

Isolation of proanthocyanidins from Siberian larch bark (Larix sibirica Ledeb.) with water and 15 % aqueous-ethanol solution was carried out. It was found that the use of 15 water-ethanol solution allows increasing the yield of proanthocyanidins from 0.75 % to 0.92 %. The composition of proanthocyanidins isolated from larch bark was characterized using UV, FTIR and 13C NMR spectroscopy. By transformation of the obtained proanthocyanidins in the presence of hydrochloric acid into colored anthocyanidins, flavonoids such as delphinidin, cyanidin and pelargonidin were identified in their composition. It was found that larch bark proanthocyanidins contain 54.5 % prodelphinidin, 40.6 % procyanidin and 4.9 % propelargonidin. It has been shown that preliminary extraction of resinous substances from the bark does not have a significant effect on the yield of extracted proanthocyanidins