A cascade synthesis, in vitro cholinesterases inhibitory activity and docking studies of novel Tacrine-pyranopyrazole derivatives

In this work, we describe the preparation of some new Tacrine analogues modified with a pyranopyrazole moiety. A one-pot multicomponent reaction of 3-methyl-1H-pyrazol-5(4H)-one, aryl(or hetero)aldehydes, malononitrile and cyclohexanone involving a Friedländer condensation led to the title compounds. The synthesized heterocyclic analogues of this molecule were evaluated in vitro for their AChE and BChE inhibitory activities in search for potent cholinesterase enzyme inhibitors. Most of the synthesized compounds displayed remarkable AChE inhibitory activities with IC50 values ranging from 0.044 to 5.80 µM, wherein compounds 5e and 5j were found to be most active inhibitors against AChE with IC50 values of 0.058 and 0.044 µM respectively. Molecular modeling simulation on AChE and BChE receptors, showed good correlation between IC50 values and binding interaction template of the most active inhibitors docked into the active site of their relevant enzymes.