Chemical Composition and Antimicrobial and Antioxidant Activities of three Turkish Thyme Essential Oils

The aim of present study was to compare the antioxidant and antimicrobial activities of three Thymus kotschyanus varieties on the basis of the chemical compositions of oils obtained by hydrodistillation. GC-MS analysis of the isolated essential oils from aerial parts of Thymus kotschyanus Boiss. & Hohen. var. eriophorus (Ronniger) Jalas, Thymus kotschyanus Boiss. & Hohen. var. kotschyanus and Thymus kotschyanus Boiss. & Hohen. var. glabrascens resulted in the identification of 55,, 34 and 57 constituents, respectively. The major components in the essential oils of T. kotschyanus Boiss. & Hohen. var. eriophorus (Ronniger) Jalas and T. kotschyanus Boiss. & Hohen. var. kotschyanus were described as geraniol (55.0-59.1 %) and geranyl acetate (27.1-28.8 %). The oil of T. kotschyanus Boiss. & Hohen. var. glabrascens is characterized by the high monoterpene fraction (86.5 %) and especially by the presence of carvacrol (57.2 %) and its precursor p-cymene (11.0 %). The essential oils were studied in vitro for antimicrobial activity (as inhibition zone and MIC) against fourteen bacteria strains using agar disc diffusion and broth micro-dilution methods. The oils exhibited moderate zone of inhibitions against bacteria when compared to standard antibiotics ketoconazol and chloramphenicol used as controls. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH). When compared with the antioxidative potentials of the standard compound used in this study (BHA), essential oils of the T. kotschyanus varieties studied exerted remarkable antioxidant activity.