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.