Variability in essential oil of Teucrium polium L. of different latitudinal populations

Abstract

Arial parts of 80 plants in eight populations of Teucrium polium growing in Khuzestan Province in the south of Iran were analyzed for quantitative and qualitative variation in essential oils and oil yield. The yields of essential oils ranged from 0.25 to 0.41% (w/w). Forty-three volatile compounds were identified by GC and GC–MS analysis. The sesquiterpene fraction constituted the main oil fraction of T. polium (75.6–82.6%) whereas monoterpene hydrocarbon (5.7–10.5%) occurred in smaller proportions. Major compounds with the mean relative amounts in eight populations were 11-acetoxyeudesman-4-α-ol (20.0%), α-bisabolol (17.8%), β-bisabolol (10.4%), (E)-caryophyllene (10.3%), caryophylleneoxide (4.5%), α-bisabololoxide B (4.1%) and β-pinene (3.1%). Comparison of the mean relative amounts of the essential oil components in a pair of populations located at different altitude in the same site showed a significant altitudinal effect on the variation of some essential oil components. In addition, comparisons based on the mean relative amount of the essential oil components between populations in different sites also showed significant differences among populations at different latitudes. In all four sites, the sesquiterpene/monoterpene ratio of the plants collected from the high altitude was higher compared with those collected from the low altitude. Principal components analysis based on the mean relative amounts of the essential oil components have led to the identification of four chemotypes.