Design and synthesis of novel coumarin-pyridinium hybrids: in vitro cholinesterase inhibitory activity

A novel series of coumarin-pyridinium hybrids were synthesized and evaluated as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using Ellman's method. Among synthesized compounds, 1-(3-fluorobenzyl)-4-((2-oxo-2H-chromene-3-carboxamido)methyl)pyridinium bromide (7l) was found to be the most active compound toward AChE (IC₅₀ = 10.14 µM), 1-(3-chlorobenzyl)-3-((2-oxo-2H-chromene-3-carboxamido)methyl)pyridinium bromide (7g) and 1-(2,3-dichlorobenzyl)-3-((2-oxo-2H-chromene-3-carboxamido)methyl)pyridinium chloride (7h) depicted the best BChE inhibitory activity (IC₅₀s = 0.32 and 0.43 µM, respectively). Although most compounds showed moderate to good anti-AChE activity, their anti-BChE activity was more significant and compound 7g was found as the most selective BChE with SI of 101.18. Also, kinetic study of the compounds 7g and 7l displayed a mixed type inhibition for both AChE and BChE. Furthermore, they were evaluated against β-secretase; however, they showed low inhibitory activity.