Chemical composition, olfactory evaluation and antioxidant effects of an essential oil of Thymus vulgaris L. from Germany

Abstract

The composition of an essential oil of thyme from Germany was analyzed by GC/FID and GC-MS. Thirty constituents were identified with thymol (49.6%), p-cymene (16.4%), γ-terpinene (8.0%), linalool (4.6%) and carvacrol (4.0%) as the main compounds. In addition, olfactory evaluations were made of the thyme sample, as well as correlations of odor-impressions of the single constituents with published data. A pleasant aroma, characteristic of thyme oils was determined, with some main and minor constituents as odor-active compounds. The thyme oil possessed antiradical activity with respect to DPPH, which was greater than the activities of its major individual phenolic components, carvacrol and thymol. The oil also demonstrated a scavenging effect with respect to hydroxyl radicals (OH•), exceeding the effect exercised on the DPPH radical, the respective concentrations resulting in a 50% inhibition (IC50) being 41.4 μg/mL for DPPH and 2.9 μ g/mL for OH•. Scavenging of the superoxide radical at a concentration of 50 μg/mL was 76.9%. Thyme essential oil revealed antioxidant activity in a model system comprised of a linoleic acid emulsion where, at a concentration of 0.05%, it caused 59.5% inhibition of conjugated dienes formation and 72.4% inhibition of the generation of secondary oxidized products from linoleic acid.