Compositional Analysis and Antioxidant Activities of Thymus pubescens Essential Oil from Iran

Background: The genus Thymus is one of the well-known members of the Lamiaceae, comprising about 215 species. It is a polymorphic genus in this family. Therefore, possible differences in chemical composition among polymorphs may result in differences in their biological activities. Objective: This study was designed to specify chemical composition in order to assess antioxidant activities and to characterize active constituents of essential oil of Thymus pubescens. Methods: Essential oil was collected by hydrodistillation and was analyzed using GC-MS and GCFID. Antioxidant activities were evaluated by ABTS radical cation scavenging and 0-carotene bleaching inhibition methods. Detection and identification of antioxidant components were performed by TLC-bioautography assay using ABTS center dot+ reagent. Results: GC analyses indicated the presence of 39 components, accounting for 96.64% of total constituents, with thymol (38.67%), gamma-terpinene (7.46%), and p-cymene (5.54%) as the main components. The IC50 values for antioxidant activities were equal to 1.15 (1.05 - 1.25) mu g/mL and 0.45 (0.33 - 0.62) mu g/mL for ABTS center dot+ scavenging and 0-carotene bleaching inhibition tests, respectively. TLC-bioautography of oil resulted in the identification of thymol as the major antioxidant compound. Conclusion: Essential oil exhibited very potent and significant antioxidant activities correlated well with increasing dose in vitro.