Differences in essential oil yield, composition, and bioactivity of three juniper species from Eastern Europe

Abstract

Juniperus communis L. is one of the widest spread species on earth, while J. pygmaea C. Koch. and J. sibirica Burgsd. are taxonomically controversial with some authors and the official Flora of Bulgaria recognizing them as separate species and other authors considering them sub-species of J. communis. There are current efforts on developing J. communis as agricultural crop to provide consistency of supply and quality of juniper essential oil (EO) and juniper galbuli (cones or berries). The objective of the study was to evaluate the chemical profile and antimicrobial activity of the leaf EO of juniper species collected in Bulgaria, Serbia, and Slovakia. The leaf EO content and EO composition varied among species and within species and also depended on the plant sex and location. In J. communis EO from Slovakia and Serbia, the major oil constituent was α-pinene (25.1–27.0 % and 21.8–22.2% respectively). However, sabinene (19.8–27.9%) was the major constituent in J. communis EO from Bulgaria. Monoterpene hydrocarbons (MHs) were the main group of EO constituents in J. communis from Bulgaria (17–22% α-pinene, 20–27% sabinene, and 8.8–11.7% γ-terpinene) and Serbia (25–27% α-pinene, 23–25% sabinene, and 4.9 to 5.3% γ-terpinene). J. communis oils originating from Slovakia showed more similarity to those from Bulgaria. The main group of EO constituents in J. pygmaea belonged to MHs (26–28% α-pinene, 17–19% sabinene, and 4.8–6.1% β-phellandrene). The oxygenated sesquiterpenes (OSs) were the second largest group of components in the EO of J. pygmaea, a noted difference compared with J. communis. The main group of EO constituents of J. sibirica from Bulgaria were MHs (36–44% α-pinene, 10–13% δ-3 carene, and 4.5–12% limonene). Eleven components found in the EO of J. sibirica from Bulgaria were not detected in the EOs of other species. In J. sibirica originating in Serbia, the main group of EO constituents belonged to MHs (∼ 24%, sabinene, ∼ 19% α-pinene, and 6% γ-terpinene). The results support the concept that the three junipers should be considered separate species. The leaf EOs of J. communis, J. sibirica, and J. pygmaea did not exhibit significant antimicrobial activity. The results contribute to further understanding of juniper leaf EO in Eastern Europe and can be used by policymakers and industry in conservation planning and in the development of juniper species as agricultural crops.