*2.3. Preparation of the Oils*

Samples of 300 g of the fresh stems and 200 g of shade dried stems (obtained from drying 300 gm of fresh stems) of *C. gileadensis* were used to prepare the essential oil by hydrodistillation for 5 h using Clevenger apparatus. Fresh stems were cut into pieces about 2 cm long and were utilized for oil isolation, while the intact stems were dried in in the shade under a controlled temperature for two weeks, then ground and used for oil preparation. The resulting oil layers were separated, and the condensates were extracted with ether. The ether extract was added to the separated oil and dehydrated using anhydrous sodium sulfate. The ether was then evaporated under the reduced pressure of 350 m bar leaving the essential oil (EO). Each experiment was repeated three times.
