Essential Oil Composition of Thymus trauvetteri Klokov & Desj. at Different Growing Altitudes in Mazandaran, Iran

Abstract Thymus trauvetteri Klokov & Desj. (Lamiaceae) is a permanent species that grows in some mountain rangeland of Iran including Mazandaran province. The aerial parts of Thymus trauvetteri were collected during flowering stage in June 2014, from mountain rangelands of Mazandaran province,in North of Iran. Around samples collected from four altitudes (2100 m, 2400 m, 2700 m and 3000 m) in mountain region of Mazandaran province. The goal of current research was to assess the effect of altitude on the chemical composition and function of essential oil in Thymus trauvetteri. The essential oil were obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas spectrometry (GC-MS). Based on the results, the essential oil content is between 1.01-1.51% at different altitudes. The highest essential oil (1.51%%) was extracted at an altitude of 2400 m, while it was opposite (1.01%) at an altitude of 3000 m. The main compounds essential oil of Thymus trauvetteri samples were identified: thymol (5.93%-49.75%), carvacrol (1.78%-54.02%), and p-cymen (6.98%-19.07%). According to the results, altitude was significantly (p≤ 0.05) effective on essential oil, thymol, carvacrol and p-cymen rates according to results of correlation analysis. The highest percentage of essential oil is at an altitude of 2400 m and the lowest is 3000 m above sea level. The highest percentage of thymol is in L3 (2700 m) and lowest is in L1 (2100 m). The highest percentage of carvacrol is in L3 (2700 m) and lowest is in L4 (3000 m). The highest percentage of p-cymen is in L1, L2, L3 (2100, 2400 and 2700 m, no significant difference) and lowest is in L4 (3000 m). Variations in essential oil rates and compositions may be due to on genetic, ecological or individual variability.