Chemical compositions of essential oils from different parts of Centaurea depressa M. Bieb.

Centaurea depressa M. Bieb. (wheat flower) is a medicinal plant that its extraction is used for eye irrigation and somewhat reduces gastrointestinal irritation. This research was aimed to investigate the essential oil of C. depressa. Different organs of C. depressa were collected from Damavand and Tehran at flowering stage. The plant organs including stem plus leaf, root and inflorescence were separated and dried at laboratory temperature and then were ground to small particles. Essential oils were obtained by hydro-distillation method and analyzed by GC and GC/MS. The yield of essential oil of stem plus leaf, root and inflorescence of Damavand samples were 0.18%, 0.13% and 0.07% w/w (dried weight), respectively and for Tehran samples the values of 0.10%, 0.13% and 0.08% were recorded, respectively. In Damavand, the major constituents of essential oil obtained from stem plus leaf, root and inflorescence were thymol (56.5%), spathulenol (12.7%) and germacrene D (9.9%); pentadecadiene-1-ol (32.2%) and Z-7-hexadecene (29.5%); and germacrene D (32.4%), germacrene B (9.4%) and thymol (8.7%), respectively. In Tehran, the major constituents of essential oil obtained from stem plus leaf, root and inflorescence were Spathulenol (25.4%), Eudesms-4(15)-7-diene-1-b-ol (14.5%) and germacrene D (13.7%); tetradecanal (30.7%), caryophyllene oxide (23.7%) and Z-7-hexadecene (22.3%); and tetradecanal (82.3%) and Z-7-hexadecene (15.5%), respectively. According to the results, it can be concluded that there is variability in essential oil compositions of the two sites and even in different plant's organs.