Diversity of Needle Terpenes Among Pinus Taxa

Essential oils are mixtures of volatile compounds often found in the leaves, wood, and fruits of coniferous trees and shrubs. The composition and abundance of individual oil components vary across different plant parts. Terpenes (monoterpenes, sesquiterpenes, diterpenes, triterpenes) dominate in the essential oils of many plants. They are the most abundant class of secondary metabolites, with plants containing over a hundred of them at varying concentrations. The terpene profile of certain species consists of a few dominant (abundant) components and numerous less abundant ones. It is believed that the biological activity of essential oil mostly depends on the dominant terpene components. In most of the analyzed Pinus species, the most abundant terpene compounds are α-pinene, β-pinene, δ-3-carene, β-caryophyllene, limonene/β-phellandrene, and germacrene D. In certain taxa, additional dominant compounds include α-cedrol, bornyl acetate, caryophyllene oxide, α-phellandrene, trimethylbicyclo [3.1.1]hept-2-ene, 2H-benzocyclohepten-2-one, phenylethyl butyrate, 4-epi-isocembrol, β-thujene, and thunbergol. Moreover, compounds with abundances exceeding 15% include methyl chavicol (=estragole), geranylene, myrcene, γ-muurolene, sabinene, and abieta-7,13-diene. It can be concluded that the terpene profiles of the needles of the analyzed pine taxa depend on the type of chromatographic columns, the method of obtaining essential oils, the origin of the trees (in natural habitat or artificial plantation), the age of the needles, the variety, and the season in which the needles were collected.