Investigation of the Effect of Extraction Duration on the Essential Oil Content and Composition of Zataria multiflora and Thymus daenensis under Flowering Stages

Thymus species are well known as medicinal plants because of their biological and pharmacological properties. Zataria multiflora and Thymus daenensis are two valuable medicinal plants which are extensively used in Iranian traditional medicine. Essential oil of Zataria multiflora and Thymus daenensis is a rich source of thymol which gives high antimicrobial and antioxidant activity to these plants. In this research, the aerial parts of Z. multiflora Boiss. and T. daenensis Celak. were collected at the reproductive phase and dried in shade. Extraction operation for each plant was done in 3 duration treatments of one, two and three hours with 3 replications using clevenger apparatus. Essential oils from each treatment were combined, identified and analyzed by GC and GC/MS. The highest percentage of essential oil of Z. multiflora Boiss. Was obtaind in two hours treatment and in T. daenensis Celak. in one and three hours. The main constituents of Zataria multiflora Boiss. were carvacrol (29.2%) and thymol (27.6%) in two hours treatment, linalool (19.5%), terpinene (6.1%) and p-cymene (4.8%) in three hours treatment; while in Thymus daenensis Celak. thymol (36.7 %), geraniol (12.7%) and borneol (4.6%) in one hours treatment, carvacrol (30.4%) in two hours treatment and linalool (6.5%) in three hours treatment. In conclusion, the best extraction duration for Z. multiflora essential oil is two hours, whereas for T. daenensis, is one hour. Therefore, the process will become cost effective, accordingly.