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

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.

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.

Essential oil was collected by hydrodistillation and was analyzed using GC-MS and GCFID. Antioxidant activities were evaluated by ABTS radical cation scavenging and β-carotene bleaching inhibition methods. Detection and identification of antioxidant components were performed by TLC-bioautography assay using ABTS•+ reagent.

GC analyses indicated the presence of 39 components, accounting for 96.64% of total constituents, with thymol (38.67%), γ-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) μg/mL and 0.45 (0.33 - 0.62) μg/mL for ABTS•+ scavenging and β-carotene bleaching inhibition tests, respectively. TLC-bioautography of oil resulted in the identification of thymol as the major antioxidant compound.

Essential oil exhibited very potent and significant antioxidant activities correlated well with increasing dose in vitro.