Ionic liquid mediated synthesis of mono- and bis-spirooxindole-hexahydropyrrolidines as cholinesterase inhibitors and their molecular docking studies

One pot, three-component reaction of 1-acryloyl-3,5-bisarylmethylidenepiperidin-4-ones with isatin and sarcosine in molar ratios of 1:1:1 and 1:2:2 furnished to mono- and bis-spiropyrrolidine heterocyclic hybrids comprising functionalized piperidine, pyrrolidine and oxindole structural motifs. Both mono and bis-spiropyrrolidines displayed good inhibitory activity against acetylcholinesterase (AChE) with IC50 values of 2.36–9.43 μM. For butyrylcholinesterase (BChE), mono-cycloadducts in series 8 with IC50 values of lower than 10 μM displayed better inhibitory activities than their bis-cycloadduct analogs in series 9 with IC50 values of 7.44–19.12 μM. The cycloadducts 9j and 8e were found to be the most potent AChE and BChE inhibitors with IC50 values of 2.35 and 3.21 μM, respectively. Compound 9j was found to be competitive inhibitor of AChE while compound 8e was a mixed-mode inhibitor of BChE with calculated Ki values of 2.01 and 6.76 μM, respectively. Molecular docking on Torpedo californica AChE and human BChE showed good correlation between IC50 values and free binding energy values of the synthesized compounds docked into the active site of the enzymes.

Ionic liquid mediated, [3+2]-cycloaddition of dipolarophile 5 to isatin and sarcosine in 1:1:1 and 1:2:2 molar ratios afforded spiropyrrolidines 8 and 9, which evaluated for their AChE/BChE inhibitory activities.Figure optionsDownload as PowerPoint slide