Synthesis and molecular docking studies of 5-trifluoromethoxy-2-indolinones as cholinesterase dual inhibitors

Background: In Alzheimer's disease, butyrylcholinesterase (BuChE) activity gradually increases, while acetylcholinesterase (AChE) activity decreases or remains unchanged. Dual inhibitors have important roles in regulation of synaptic acetylcholine levels and progression of Alzheimer's disease. Methods: 1-(Thiomorpholin-4-ylmethyl)/benzyl-5-trifluoromethoxy-2-indolinones (6-7) were synthesized. AChE and BuChE inhibitory effects were investigated with Ellman's method. Molecular docking studies were performed for analyzing the possible binding interactions at active sites. Results: Compound 6g was the strongest inhibitor against both AChE (Ki = 0.35 mu M) and BuChE (Ki = 0.53 mu M). It showed higher inhibitory effects than both donepezil and galantamine. Moreover, compound 7m had a higher inhibitory effect than galantamine and the effect was comparable to that of donepezil against both AChE (Ki = 0.69 mu M) and BuChE (Ki = 0.95 mu M). Conclusion: The benzyl substitution compared with 1-(thiomorpholin-4-ylmethyl) group significantly increased both AChE and BuChE inhibitory effects.