A Practical and High‐Affinity Fluorescent Probe for Butyrylcholinesterase: A Good Strategy for Binding Affinity Characterization

Comprehensive Summary Butyrylcholinesterase (BChE) is regarded as a promising target for the treatment of Alzheimer's disease (AD), as its level significantly increases along with the progress of this disease. Therefore, the development of potent and high‐affinity small‐molecule BChE inhibitors may be a new strategy for the discovery of anti‐AD drugs. However, the current Ellman's method is unable to evaluate the affinity of compounds with BChE, and has a few deficiencies in drug development. Herein, the first small‐molecule fluorescence polarization (FP) probes for BChE were rationally designed based on a high affinity inhibitor. Studies indicated that probe F6 exhibited satisfactory fluorescence intensity and suitable fluorescent properties that were compatible with the filters in the FP system. Meanwhile, probe F6 exhibited potent binding affinity to BChE. It is feasible to be applied in detecting the affinity of non‐fluorescent compounds to BChE, which lays a solid foundation for the development of small‐molecule BChE inhibitors. At the same time, it also can be applied as a valuable chemical tool for better understanding the molecular biological mechanism of BChE.