Abstract:
This is the first detailed chromatographic examination of Pseudotsuga menzesii and three other Pseudotsuga species (P. macrocarpa, P. japonica, and P. wilsoniana). The whole bark of these four species was sequentially extracted with hexane, benzene, ethyl ether, ethyl alcohol and water. Paper and thin layer chromatographic techniques were coupled with ultraviolet spectral procedures in-the isolation and identification of individual compounds. Compounds identified and previously reported which were common to all species included: dihydroquercetin, quercetin, dihydroquercetin-3'-monoglucoside , 1-epicatechin, d-catechin, vanillin, protocatechuic acid, coniferaldehyde and leucoanthocyanins. Compounds discovered in the four species which have not previously been reported include: eriodictyol, vanillic acid, vanillyl alcohol, acetovanillone, and at least two esters of ferulic acid. Some compounds were identified which were not distributed through all four species. These included: luteolin (P. macrocarpa, P. japonica, and P. wilsoniana), and four leucoanthocyanins (variable distribution among the four species). Other unidentified compounds displayed selective distribution patterns as well. The selective distribution patterns of these flavonoid compounds suggests their possible application in chemical taxonomic differentiation of Pseudotsuga species. However, such an application must wait for extractive analysis of the two unavailable species of Pseudotsuga (P. sinensis and P. forestii). Comparison of the flavonoids present in the bark with those reported in other tissues of the tree supports the view that such compounds are formed in situ and certain preliminary biosynthetic observations are discussed. The extractive distribution of the compounds found in the bark is considered in light of the possibility that such compounds may eventually make the more complete utilitation of bark a reality. Such utilization, however, is dependent upon the establishment of suitable markets for these compounds.
