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 β-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)-β-farnesene (9.43%). The major constituents identified in the post-flowering oil were camphor (16.62%), caryophyllene (16.27%), β-caryophyllene oxide (15.84%), β-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.