Schiff Bases of Isatin: Inhibitory Potential Towards Acetylcholinesterase and Butyrylcholinesterase

A series of different Schiff bases of isatin 1-20 was synthesized by the condensation of isatin with primary aromatic amines. It was observed that some of these compounds have the potential to inhibit acetylcholinesterase, whereas some others showed specific activity against butyrylcholinesterase, depending upon substitution on the aromatic ring. Compounds 9 and 20 showed weak acetylcholinesterase inhibitory activity having IC50 values 28.3 ± 0.26 and 159 ± 2.9 μM, respectively. Nonetheless, compounds showed a varying degree of activity against butyrylcholinesterase with IC50 values in the range of 2.8 ± 0.07-82.9 ± 2.2 μM. Compounds 5, 2, and 11 showed IC50 values 2.8 ± 0.07, 5.2 ± 0.10, and 8.1 ± 0.30 μM, respectively, Their activity was compared with standard inhibitor galanthamine IC50 = 0.5 ± 0.01 μM for acetylcholinesterase and IC50 = 8.5 ± 0.01 μM for butyrylcholinesterase, respectively. The structures of all the synthesized compounds were confirmed by spectroscopic analysis.