Effect of Geographical Location on Yield and Chemical Composition of Teucrium orientale L. Essential Oils Collected from Eleven Different Localities in Iran

Essential oils of the air-dried aerial parts of Teucrium orientale L. collected from 11 different localities which obtained by hydro-distillation were investigated. The essential oils were analyzed by GC-FID and GC-MS. The oil yields were 0.03–0.20% (w/w), based on dry weight. Forty-four components, representing 91.0–99.5% of the oils, were identified. The results showed that there is a significant difference in yields, chemical compositions and concentrations of essential oils obtained from different geographical regions. However, there are main and common compounds such as caryophyllene oxide (3.72 to 23.60%), E-caryophyllene (1.03 to 39.36%), germacrene D (0.95 to 29.7%), spathulenol (1.98 to 11.11%), β-cubebene (1.31 to 24.64%), δ-cadinene (1.14 to 4.90%), hexadecanoic acid (0.47 to 32.60%), α-cubebene (0.53 to 11.37%) and hexahydrofarnesyl acetone (0.34 to 10.56%) that are found in all essential oils. According to the cluster analysis, the populations were placed in three clusters. Percentages of hexahydrofarnesyl acetone (10.6%) and humulene epoxide II (6.8%) were considerably higher in cluster 1 compared to other clusters. Percentages α-cubebene, β-cubebene and hexadecanoic acid were considerably highest in cluster 2 with means of 7.2%, 11.9% and 20.4% respectively. Populations of cluster 3 were rich sources of E-caryophyllene (29.4%), germacrene D (16.1%) and bicyclogermacrene (3.4%) compared to other clusters.