ISOLATION AND STUDY OF PROANTHOCYANIDINS FROM BARK OF PINE PÍNUS SYLVÉSTRIS L.

The isolation of proanthocyanidins from bark of Scotch pine Pínus sylvéstris L. by water and water-alcohol solutions containing 5, 10, 15, 20 and 25% ethanol was studied for the first time. Isolation of proanthocyanidins was carried out from the initial and deresinified (extracted with hexane) pine bark. It was shown that, compared with water extraction, the use of 15–25% aqueous ethanol solutions allows one to increase the yield of proanthocyanidins from 0.44 to 0.63%. It was established that the preliminary extraction of resinous substances from the pine bark does not significantly affect the yield of proanthocyanidins. It was shown that an increase in ethanol concentration of more than 20% in the extraction solution leads to an increase in the total yield of extractives, while the yield of proanthocyanidins does not increase. A study of proanthocyanidins by UV spectroscopy after their conversion to red anthocyanidins showed that they mainly consist of procyanidin and prodelphinidine in close concentrations. The composition of the obtained proanthocyanidins mixtures was studied by IR and 13C NMR spectroscopy. It was shown that the proanthocyanidins obtained from the bark of pine Pínus sylvéstris L., in contrast to isolated from other pine species, contains gallic acid residues which can increase their antiradical activity.

Isolation and Study of Abies Bark Proanthocyanidins

The process of proanthocyanidins isolation from abies bark by water and water-alcohol solutions containing 5, 10, 15 and 20 % ethanol was studied for the first time. The optimal conditions providing the maximum yield of proanthocyanidins were determined experimentally. It was shown that the use of 15-20 % water-alcohol solutions allows to increase the yield of proanthocyanidins from 0.33 to 0.38 %. The composition of the obtained proanthocyanidins was studied by UV, IR, and 13C NMR spectroscopy. The obtained proanthocyanidins were transformed into colored anthocyanidins in ethanol medium in the presence of hydrochloric acid. The flavonoids cyanidin and delphinidin were isolated and identified. It was established that the obtained proanthocyanidins mainly consist of procyanidin and prodelphinidin. It was shown that proanthocyanidins obtained from abies bark, in contrast to the proanthocyanidins isolated from pine bark described in the literature, contain gallic acid residues, which is typical for proanthocyanidins isolated from various types of tea