Chemical Composition and Anti-acetylcholinesterase Activity of Flower Essential Oils of Artemisia annua at Different Flowering Stage

The chemical composition of the essential oils of flower at the pre-flowering, full-flowering and post-flowering stage of a. annua was analyzed by gc and gc/ms and sixty-two components were identified. the main compounds in the pre-flowering oil were (beta)-myrcene (37.71%), 1, 8-cineole (16.11%) and camphor (14.97%). the full-flowering oil contained predominantly caryophyllene (19.4%), germacrene d (18.1%), camphor (15.84%), 1, 8-cineole (10.6%) and (z)-(beta)-farnesene (9.43%). the major constituents identified in the post-flowering oil were camphor (16.62%), caryophyllene (16.27%), (beta)-caryophyllene oxide (15.84%), (beta)-farnesene (9.05%) and (-)-spathulenol (7.21%).the variety of anti-ache activity of flower oil of a. annua at three flowering stage might be a result of the variety of the content and interaction of those terpenoids with anti-ache activity. the greatest acetylcholinesterase inhibitory activity (ic50 = 0.13 ± 0.02 mg ml^-1) was exhibited by the essential oil of flower of a. annua at post-flowering stage.