We screened 42 Korean traditional
tea plants to determine the inhibitory effect of
acetylcholinesterase and attenuation of toxicity induced by
amyloid-beta peptide, which were related to the treatment of
Alzheimer's disease (AD). The methanolic extract from Artemisia asiatica among tested 42
tea plants, showed the highest inhibitory effect (48%) on
acetylcholinesterase in vitro. The methanolic extract was further separated with
n-hexane,
chloroform, and
ethyl acetate of water, in order. The
chloroform solubles, which were high in inhibitory effect of
acetylcholinesterase, were repeatedly subjected to open column chromatography on
silica gel. From the highest inhibitory fraction (78%) on
acetylcholinesterase, the single compound was obtained by the Sep-Pak Cartridge (C18: reverse phase column). This compound was found to react positively on Dragendorff's
reagent (
potassium bismuth iodide), which typically reacted with the
alkaloid. This compound was purified by HPLC (mu-bondapack C18 reverse phase column: 3.9 x 150 mm). The IC50 (the concentration of 50%
enzyme inhibition) value of this compound was 23 micrograms/ml and the inhibitory pattern on
acetylcholinesterase was mixed with competitive/non-competitive type. We examined the effects of this compound on toxicity induced by A beta (25-35) in rat
pheochromocytoma PC12 cells. Pretreatment of the PC12 cells for 2 h with an
alkaloid of Artemisia asiatica (1200 microg/ml) reduced the toxicity induced by A beta. This study demonstrated that an
alkaloid of Artemisia asiatica, which was metabolized to small molecule in digestive tract and then could pass through the blood-brain barrier, appeared to be an
acetylcholinesterase inhibitor with a blocker of neurotoxicity induced by A beta in human brain causing
Alzheimer's disease.