Abstract: Objective： To establish a reliable, fast, convenient and economical method of screening acetylcholinesterase inhibitors, and use it to screen acetylcholinesterase inhibitors from extracts of plants. Methods： Using the optimized Ellman method, we examined the inhibition effects of tacrine and huperzine on acetylcholinesterase enzyme from electric eel, human erythrocyte, rat hippocampus, striatum homogenate in 96-well plates under physiological pH value and temperature. The concentrations of AChE, substrate and DTNB, and reaction time were optimized. We also detected the inhibition effect of plant extracts on AChE. Results： Practical microassays for screening AChE inhibitors were successfully established by using AChEs mentioned above. The data analysis of screening results revealed that electric eel AChE possessed a high sensitivity to inhibitors, whereas human erythrocyte AChE shared high similarity with rat brain homogenate, on which the inhibitory effect of huperzine was superior to tacrine. However the plant extracts showed no inhibitory effect on AChE. Conclusion： The screening method established in this experiment is simple, fast, reliable and economical, and it can be used for pure compound screening.

Key words: acetylcholinesterase, huperzine, tacrine, Alzheimers disease