Preparation of 7‐Methoxy Tacrine Dimer Analogs and Their In vitro/In silico Evaluation as Potential Cholinesterase Inhibitors

Abstract

Novel types of symmetric bis‐7‐methoxytacrines connected by oligoethyleneoxy chains 3–5 and nonsymmetric monomeric 7‐methoxytacrines containing hydroxyl‐terminated oligoethyleneoxy chains 6–8 were prepared, and their in vitro/in silico effects on human recombinant AChE (hAChE) and human plasmatic butyrylcholinesterase (hBChE) were compared, with 7‐MEOTA (2) as the standard compound. The symmetric bis‐7‐MEOTA derivatives 3–5 showed hAChE inhibition similar to that of 2. On the other hand, their effects on hBChE revealed an increasing inhibition trend when the oligoethyleneoxy units between the two 7‐MEOTA moieties became longer. Accordingly, compounds 4 and 5 showed better selectivity towards hBChE. The most effective in the inhibition hAChE and hBChE was compound 8 with the longest oligoethyleneglycol chain, whereas compounds 6 and 7 resulted in similar IC50 values. A molecular modeling study using substrates 5 and 8 showed a possible binding conformation and protein–ligand interaction between the substrates and AChE/BChE.