Synthesis, characterization and investigation of AChE and BuChE inhibitory activity of 1-alkyl-4-[(5,6-dimethoxy-1-indanone-2-yl)methylene]pyridinium halide derivatives

The design, synthesis and characterization of a series of 1-alkyl-4-[(5,6-dimethoxy-1-indanone-2-yl)methylene]pyridinium halide derivatives as acetylcholinesterase and butyrylcholinesterase inhibitors for the treatment of Alzheimer's disease were reported. The strategy for this synthesis was based on aldol condensation reaction between 4-pyridinecarboxaldehyde with 5,6-dimethoxy-1-indanone in the presence of NaOH in EtOH-H2O solution as the first step and N-alkylation reaction of the produced 5,6-dimethoxy-2-[(pyridin-4-yl)methylene]-1-indanone with various alkyl halides (R-X) in the second step. This reaction was carried out under reflux temperature in polar aprotic solvents such as acetone or acetonitrile. H-1 and C-13 NMR and FTIR spectroscopy along with CHN analysis were used to confirm the structure of our synthesized compounds. Biological activities including acetylcholinesterase and butyrylcholinesterase (BuChE) inhibitions for synthesized compounds were tested using the Ellman method. The results were compared with donepezil and galantamine, and among the synthesized compounds, the highest inhibitory activity with BuChE IC50 = 0.55 mu M was observed. Graphic abstract