Analysis and comparison of essential oil components extracted from the heartwoods of Leyland cypress, Alaska yellow cedar, and Monterey cypress

Graduation date: 2009The essential oil components of cedar heartwoods play an important role in the durability of these trees. Yet, the composition of these oils and identity of many of the compounds remains unknown, or incompletely know for some commercially important cedar heartwoods. The essential oil extracts of Alaska Yellow Cedar (Chamaecyparis nootkatensis), Monterey Cypress (Cupressus macrocarpa), and Leyland Cypress (xCupressoparis leylandii ) which is an intergenetic hybrid of the first two species is such a case. GC-MS analyses were carried out on the heartwood essential oil extracts of these three species in order to determine the chemical composition of each essential oil and to compare the composition of the intergenetic hybrid (Leyland Cypress) with its parent species. Analyses were carried out on both steam distilled (6 and 12 hour) and solvent extracted oils. For example in the 6 hour distilled oils, Carvacrol was the major component of all three oils, 27% (Alaska Cedar), 67% (Leyland Cypress) and 82% (Monterey Cypress). Terpinen-4-ol and nootkatin were also found in all three oils, but in lesser amounts (3-6%). Only the oils from Alaska cedar and Leyland cypress contained the eremophilane sesquiterpenoids valencene, nootkatene, epinootkatol, nootkatol, 13-hydroxy valencene and nootkatone. This family of compounds was completely absent in Monterey cypress oil. Carvacrol, nootkatin and the eremophlianes make up 68-90% of the oils of all three species. Similar results were obtained with the 12 hour steam distilled and solvent extracts. As an intergenetic species, the components in the essential oil from Leyland Cypress show an intermediate amount of the above compounds when compared to its parents. However, the amount of hinokitiol (a monoterpene tropolone) in Leyland cypress surpassed both of its parents. It is expected that Leyland Cypress should have similar antifungal and insect resistant properties as Alaska cedar according to the essential oil components, which needs to be confirmed by future studies. Leyland cypress also shows promise for a source of important biobased chemicals such as nootkatone and its related compounds given the fast growth of this tree