Colorimetric and fluorometric assays for acetylcholinesterase and its inhibitors screening based on a fluorescein derivate.

A fluorescein-based sensor was developed for the AChE activity assay and the inhibitor screening. The sensor provided the dual assay methods for the screening of AChE activity in the presence or absence of inhibitor. The colorimetric and fluorometric assays were based on the following processes: (1) owing to the hydrolysis of acetylthiocholine in the presence of AChE, the fluorescein-based probe can rapidly induce 1,4-addition of the hydrolysis product thiocholine to α,β-unsaturated ketone in the compound 1, resulting in strong fluorescence and absorption changes; (2) in the presence of the corresponding inhibitor, the fluorescence enhancement or the absorption change would be inhibited in that the formation of thiocholine was hindered.