Gas Chromatography-Mass Spectrometry Analyses for Detection and Identification of Antioxidant Constituents ofAchillea tenuifoliaEssential Oil

The present work was designed to study the antioxidant activity and to identify the main active components of the essential oil of Achillea tenuifolia aerial parts. Gas chromatography-mass spectrometry analyses of the essential oil showed the presence of 22 compounds. The main constituents of the oil were thymol (15%), α-pinene (10.11%), Camphene (9.41%), β-pinene (7.54%), α-terpinene (7.21%), p-cymene (4%), 1,8-cineole (2.31%), γ-terpinene (7%), linalool (10%), and carvacrol (20.43%). The antioxidant and free radical scavenging activities of Achillea tenuifolia oil was evaluated by using 2,20-diphenyl-1-picrylhydrazyl assays. The oil exhibited a considerable dose-dependent antioxidant activity. Thymol showed clearly a higher activity (IC50 = 10.04 ± 0.1 μg/ml) followed by Achillea tenuifolia essential oil (15.12 ± 0.4 μg/ml). Antioxidant activity guided fractionation of the oil was carried out by the thin layer chromatography-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which was identified as thymol (80%).