Essential Oil Compositions and Site Characteristics of Sideritis pisidica in Natural Habitat

In the present work, natural populations of Sideritis pisidica Boiss. & Heldr. from 19 different localities in Turkey have been comprehensively investigated with taking into consideration the environmental factors and phytochemical composition and yield of the essential oils. The essential oils were obtained by the hydrodistillation of the aerial parts of plant samples. The chemical compositions of the essential oils were analyzed with GC-FID and GC/MS techniques. The main chemical compositions were evaluated with the Principal Component Analysis. The relationship between the oil yields, main chemical constituents, and site factors were determined by correlation analysis. A total of 188 compounds and 6 main constituents were detected in the essential oils of S. pisidica. In general, the oils were mostly constituted by monoterpene hydrocarbons, oxygenated sesquiterpene, sesquiterpene hydrocarbons and diterpenes. β-Caryophyllene (0–40.3%), α-pinene (0–27.8%), sabinene (0–17.6%), α-bisabolol (0–20.9%), myrcene (0–13.8%), β-pinene (0–14.1%), caryophyllene oxide (0.2–13.3%) and 2-keto-manoyloxide (0–25.8%) were found in high amounts. There was a positive relationship between the amount of Mn in the soil and sabinene, β-pinene and linalool and caryophyllene II, but there was a negative relationship with caryophyllene oxide. As the elevation and Ca amount increased, the ratio of 2-keto-manoyloxide and diterpene-IV from the diterpenes increased, too, but the myrcene decreases. In conclusion, data about essential oil compositions and site factors in studied S. pisidica samples could provide useful informations for conservation, cultivation and for clone selection in breeding studies. In addition, the chemical distribution of the essential oil compounds could be useful in means of chemotaxonomy.