en The Effect of Distillation Methods and Plant Growth Stages on the Essential Oil Content and Composition of <i>Thymus daenensis</i> فارماكوگنوزی و فارماسيوتيكس Pharmacognosy & Pharmaceutics پژوهشی Research <div dir="ltr" style="text-align: justify;"><strong>Background:</strong> <em>Thymus daenensis</em> is on e of the endemic aromatic species in Iran that its essential oil is used in food and pharmaceutical industries. <strong>Objective:</strong> In this study, the effects of plant growth stages and distillation methods on essential oil content and thymol percentage of this species were evaluated. <strong>Methods:</strong> The aerial parts of <em>Th. daenensis</em> were collected in three stages of plant growth from Tehran province of Iran. The plant materials were dried in shade and their essential oils were isolated by hydro-distillation in three replications. In addition, the essential oils of plant materials at full flowering stage were obtained by hydro-distillation, water&steam distillation and steam distillation. The essential oils were analyzed by capillary GC and GC/MS. <strong>Results:</strong> The result showed that the different plant growth stages and distillation methods had significant effect on essential oil content. The highest essential oil content was obtained at full flowering stage (2.28% w/w). Among distillation methods, the highest essential oil content was obtained by hydro-distillation (2.27%) that was significant difference with other distillation method. There was no significant difference between essential oil composition at different plant growth stages. Also, thymol, p-cymene and -terpinene were the main components. The highest percentage of thymol was obtained by hydro-distillation. <strong>Conclusion:</strong> Generally, it can be concluded that harvesting of <em>Th. daenensis</em> at full flowering stage and extraction of its essential oil by hydro-distillation were more suitable for obtaining the higher oil content and thymol percentage.</div> <div dir="ltr" style="text-align: justify;"><strong>Background:</strong> <em>Thymus daenensis</em> is on e of the endemic aromatic species in Iran that its essential oil is used in food and pharmaceutical industries. <strong>Objective:</strong> In this study, the effects of plant growth stages and distillation methods on essential oil content and thymol percentage of this species were evaluated. <strong>Methods:</strong> The aerial parts of <em>Th. daenensis</em> were collected in three stages of plant growth from Tehran province of Iran. The plant materials were dried in shade and their essential oils were isolated by hydro-distillation in three replications. In addition, the essential oils of plant materials at full flowering stage were obtained by hydro-distillation, water&steam distillation and steam distillation. The essential oils were analyzed by capillary GC and GC/MS. <strong>Results:</strong> The result showed that the different plant growth stages and distillation methods had significant effect on essential oil content. The highest essential oil content was obtained at full flowering stage (2.28% w/w). Among distillation methods, the highest essential oil content was obtained by hydro-distillation (2.27%) that was significant difference with other distillation method. There was no significant difference between essential oil composition at different plant growth stages. Also, thymol, p-cymene and -terpinene were the main components. The highest percentage of thymol was obtained by hydro-distillation. <strong>Conclusion:</strong> Generally, it can be concluded that harvesting of <em>Th. daenensis</em> at full flowering stage and extraction of its essential oil by hydro-distillation were more suitable for obtaining the higher oil content and thymol percentage.</div> ,Thymus daenensis, Distillation methods, Essential oil, Plant growth stages, Thymol Thymus daenensis, Distillation methods, Essential oil, Plant growth stages, Thymol 93 100 http://jmp.ir/browse.php?a_code=A-10-571-1&slc_lang=en&sid=1 F Nikkhah F Nikkhah 100319475328460041816 100319475328460041816 No Islamic Azad University of Science and Research of Tehran, Tehran, Iran Islamic Azad University of Science and Research of Tehran, Tehran, Iran V Abdossi V Abdossi 100319475328460041817 100319475328460041817 No Department of Horticulture, Collage of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran Department of Horticulture, Collage of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran F Sefidkon F Sefidkon 100319475328460041818 100319475328460041818 No Research Institute of Forests and Rangelands, Tehran, Iran Research Institute of Forests and Rangelands, Tehran, Iran E Sharifi Ashoorabadi E Sharifi Ashoorabadi 100319475328460041819 100319475328460041819 No Research Institute of Forests and Rangelands, Tehran, Iran Research Institute of Forests and Rangelands, Tehran, Iran MR Dehghani-Mashkani MR Dehghani-Mashkani Mdehghani1350@yahoo.com 100319475328460041820 100319475328460041820 Yes Biotechnology Department of Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran Biotechnology Department of Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran