A comparison of quantitative and qualitative essential oil yield in different species of thyme (Thymus spp.) in the natural habitats of Kurdistan province

This study was conducted to evaluate the essential oil (EO) quality and quantity of six thyme species (Thymus spp.), growing in the natural habitats of Kurdistan province, in 2010. To conduct this research, six species of thyme were identified in different habitats and used for essential oil extraction. Water distillation (Clevenger-type apparatus) was used to obtain the EOs and the components were identified using the gas chromatography (GC) system and a gas chromatograph connected to mass spectrometer (GC/MS). The results showed that more than 30 components were identified in the EOs, among which thymol, carvacrol, geraniol, alpha terpinole and linalool were the most important components. The EO yields were 3.05%, 2.53%, 2.83%, 1.51%, 1.31% and 1.05% for T. fallax, T. daenensis, T. pubescens, T. transcaucasicus, T. fedtschenkoi and T. kotschyanus, respectively. The content of thymol was calculated to be 70.6%, 62.2%, 27.8% and 1.5 in the EOs of T. daenensis, T. fedtschenkoi, T. pubescens and T. kotschyanus, respectivelyand the content of carvacrol was recorded to be 3.43%, 4.80% and 0.74% in the EOs of T. daenensis, T. fedtschenkoi and T. pubescens, respectively.