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

Abstract

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.