ISOLATION AND STUDY OF PROANTHOCYANIDINS FROM BARK OF CEDAR PÍNUS SIBÍRICA

Abstract

The yields of proanthocyanidins isolated from the initial and deresinated (extracted with hexane) bark of the Siberian cedar (Pínus sibírica) by water, 15% water-ethanol solution and ethyl acetate in a Soxhlet apparatus were compared. It was shown, that the preliminary removal of resinous substances from the cedar bark does not affect the yields of proanthocyanidins extracted with water and 15% water-ethanol solution (for the initial bark is 0.44% (wt.) and 0.57% (wt.) and for the deresinated bark is 0.43% (wt.) and 0.57% (wt.), respectively). It was established that the extraction of deresinated bark with ethyl acetate makes it possible to increase the yield of proanthocyanidins about 2 times to 1.04% (wt.). The composition of the proanthocyanidins isolated from the cedar bark was characterized by UV, FTIR, and 13C NMR spectroscopy methods. The flavonoids cyanidin and delphinidin were identified using the conversion proanthocyanidins to anthocyanidins. The proanthocyanidins isolated from cedar bark mainly consist of procyanidin and prodelphinidin, regardless of the method of their isolation – extraction by water, 15% aqueous ethanol solution or ethyl acetate. It was established that the proanthocyanidins isolated from the bark of cedar, in contrast to those isolated from the bark of pine (Pinus maritima) and (Pinus radiata), contain gallic acid residues.