Determinations of Physicochemical Properties, Proximate Compositions, and Characterization of Chemical Constituents of Thymus schimperi Essential oil

Abstract

Thymus schimperi is endemic to Ethiopia and it is well-known in central, eastern and northern parts of the country. Investigation has been carried out to determine the physicochemical properties, and to analyze the proximate values of the leaves and chemical composition of T. schimperi leaf essential oils grown at Ankober district, Ethiopia. To get the essential oil, the shade dried ground leaves of T. schimperi were subjected to hydrodistillation for 3 h using a Clevenger-type apparatus. The percent yield of the leaf essential oil (1.85 %), physicochemical properties of the oil such as refractive index (1.484), relative density (0.941), optical rotation (-1.8o), solubility (insoluble in water and soluble in ethanol), color (yellowish) and odor (aromatic) were determined. Analysis of the proximate values of T. schimperi leaves such as total ash, water soluble ash; acid insoluble ash, moisture content and pH were found to be 9.14, 3.34, 2.52, 12.4 and 6.17, respectively. The essential oil of T. schimperi was analyzed using GC-MS and a total of thirteen volatile components, representing 98.82 % of the total composition, were identified. The main components of the essential oils are thymol (71.02 %), p-myrcene (15.25 %), ϒ-terpinene (9.02 %), Phenylethanone (1.33 %) and α-phellandrene (1.062 %).