Essential oils have the strong potency to inhibit acetylcholinesterase (AChE) in brain because of their lipophilicity and small molecular size constituents. The anticholinesterase activity of13 essential oils from Thai medicinal plants was primarily evaluated using purified AChE from eel. Results revealed 6 of them including those from turmeric,galangal, fingerroot, plai, betel vine and holy basil showed such activity. However, only essential oils from turmeric, galangal and fingerroot exhibited the appreciable effects.Their constituents were then identified and
also investigated for AChE inhibitory activity.Results revealed a number of constituents were found but their effect on anticholinesterase activity was not impressive as their originated oils either in single or combination.When turmeric, galangal and fingerroot oils were tested in neuroblastoma SK-N-SH cells, they showed the appreciable potentials in inhibiting cellular AChE of these cells as well.