Effects of ecological conditions on antioxidant properties, quantity, and quality of Thymbra spicata L. essential oil

Thymbra spicata L. (from Lamiaceae family) is distributed in large areas of Iran. In this study, the amount of total phenols and flavonoids, antioxidant activity, and percentage and essential oil composition in different ecotypes of this species from three different regions in Ilam province was evaluated. The results showed that total phenols and flavonoids content was correlated with antioxidant activity positively and significantly, so that plant essential oil from Manesht Mountain with high phenols (8.6 mg gallic acid per g dry weight) and flavonoids (0.30 mg quercetin per g dry weight) content had the highest antioxidant activity, too. The main essential oil compound of the plant from regions with different ecological conditions was thymol (22.6-40.7%). Carvacrol, p-cymene, and γ-terpinene were the other main essential oil compounds of T. spicata from different regions. The results showed that the plant sample from Kaveran region and Manesht Mountain had the highest (2.4%) and lowest (1.4%) essential oil content, respectively. Overall, based on the results of the present study, it could be suggested that the essential oil percentage and composition of T. spicata depended not only to the genetic factors, but also to the ecological factors such as altitude, average annual temperature, and annual rainfall.