Gymnosperms of Idaho: Chemical Compositions and Enantiomeric Distributions of Essential Oils of Abies lasiocarpa, Picea engelmannii, Pinus contorta, Pseudotsuga menziesii, and Thuja plicata

Abstract

Conifers are of great economic value in terms of lumber production, important for construction and other uses such as pulp and paper. They are also important sources of essential oils. Conifer species have been vital to the ethnobotany and traditional herbal medicine of many different Native American groups. The objective of this work was to obtain and analyze the essential oils of several conifer species (Abies lasiocarpa, Picea engelmannii, Pinus contorta, Pseudotsuga menziesii, and Thuja plicata) growing in Idaho. The foliar essential oils were obtained by hydrodistillation and then analyzed by gas chromatographic methods, including GC-MS, GC-FID, and chiral GC-MS. The essential oils were obtained in varying yields from 0.66% up to 4.70%. The essential oil compositions were largely dominated by monoterpene hydrocarbons and oxygenated monoterpenoids. The chiral monoterpenoids were generally rich in the (−)-enantiomers for members of the Pinaceae, but the (+)-enantiomers predominated in the Cupressaceae. The essential oil compositions obtained in this work are qualitatively similar, but quantitatively different, to previously reported compositions and confirm and complement the previous reports. However, this is the first comprehensive analysis of the chiral terpenoid components in these conifer species. Additional research on essential oils of the Pinaceae and Cupressaceae is needed to describe the chemical profiles, chemical compositions, and enantiomeric distributions more reliably in the various species and infraspecific taxa of these two families.

Chemical Compositions and Enantiomeric Distributions of Foliar Essential Oils of Chamaecyparis lawsoniana (A. Murray bis) Parl, Thuja plicata Donn ex D. Don, and Tsuga heterophylla Sarg.

“…The essential oil compositions of the Oregon T. plicata samples were very similar to those from our previous collection from northern Idaho [49] as well as those reported by von Rudloff and co-workers [44], Tsiri and co-workers [46], Lis and co-workers [47], and Nikolić and co-workers [48]. Indeed, a hierarchical cluster analysis (HCA) reveals very high similarity between the samples (Figure 9).…”

“…In retrospect, the similarities in essential oil compositions are consistent with the genomic analysis of T. plicata; there is little genetic differentiation in this species [64][65][66]. [44], ID = samples from Idaho [49], OR = samples from Oregon (this work), Tsiri [46], Nikolic [48], Lis [47].…”

“…Notably, the samples collected in Oregon and those from Idaho and von Rudloff were found to have similar chemical characteristics, with α-thujone concentrations close to 70% and sabinene amounts of less than 5.0%. [44], ID = samples from Idaho [49], OR = samples from Oregon (this work), Tsiri [46], Nikolic [48], Lis [47]. The T. plicata samples were subjected to principal component analysis (PCA) to understand their chemical variability comprehensively.…”

“…The heartwood of T. plicata has been shown to be a source of tropone monoterpenoids [27][28][29][30][31] and lignans [32][33][34][35][36][37][38][39][40], and the dilactone thujin [41], while the bark and aerial parts have yielded diterpenoid derivatives [42,43]. There have been several investigations on the foliar essential oil compositions of T. plicata growing wild in western North America [44,45], cultivated in Poland [46,47], cultivated in Serbia [48], and growing wild in Idaho, USA [49]. In addition, the volatiles from resin extracts of T. plicata cultivated in Czechia have been reported [50].…”

“…A dendrogram obtained via the hierarchical cluster analysis of Thuja plicata foliar essential oil compositions. von Rudloff[44], ID = samples from Idaho[49], OR = samples from Oregon (this work), Tsiri[46], Nikolic[48], Lis[47].…”