effect of different distillation methods on quantity and quality of essential oil of two ziziphora l. species

background & aim: ziziphora l. genus belongs to the lamiaceae family, which has important medicinal and aromatic plant species. in current study, essential oil chemical compositions of two ziziphora l. species (z. tenuior l. and z. clinopodioides lam.) were investigated. experimental: the flowering branches of z. tenuior and z. clinopodioides were collected in spring and summer 2011. the aerial parts dried in shade at room temperature. the flowering branches of these species subjected to volatile fraction were isolated by simultaneous distillation extraction (sde), hydro distillation (using a clevenger-type apparatus), steam-cooled distillation (ultrasonic) and steam distillation. the analysis of the oils was performed by using gc and gc-ms. results & discussion: the results indicated the essential oil yield of z. tenuior ranged 0.2% to 2.3% (w/w), and z. clinopodioides ranged 0.3% to 1.3% (w/w(. in total, 18 components were identified in z. tenuior essential oil, and 33 components were identified in z. clinopodioides essential oil. the main components of z. tenuior essential oil were pulegon (80.01% - 90.10%), and piperitenone (4.5% - 7.14%). the major compounds in z. clinopodioides essential oil were pulegon (25.87% - 35.20%), piperitenone (10.11% - 27.88%), menthol (11.41%-17.50%), and menthon (0 - 7.69%). the highest percentage of menthol in essential oil in two species obtained from sde method. industrial and practical recommendations: according to the purity 81% of pulegon combination in essential oil of ziziphora with 2% essential oil yield, can be purified in production of ziziphora.