meta-Cyanobenzyl substituted benzimidazolium salts: Synthesis, characterization, crystal structure and carbonic anhydrase, α-glycosidase, butyrylcholinesterase, and acetylcholinesterase inhibitory properties

Abstract

meta-Cyanobenzyl-substituted N-heterocyclic carbene (NHC) precursors were synthesized by the reaction of a series of N-(alkyl)benzimidazolium with 3-bromomethyl-benzonitrile. These benzimidazolium salts were characterized by using ¹ H NMR, ¹³ C NMR, FTIR spectroscopy, and elemental analysis techniques. The molecular and crystal structures of 2f and 2g complexes were obtained by using the single-crystal X-ray diffraction method. The derivatives of these novel NHC precursors were effective inhibitors of α-glycosidase (AG), the cytosolic carbonic anhydrase I and II isoforms (hCA I and II), butyrylcholinesterase (BChE), and acetylcholinesterase (AChE) with K_i values in the range of 1.01-2.12 nM for AG, 189.56-402.44 nM for hCA I, 112.50-277.37 nM for hCA II, 95.45-352.58 nM for AChE, and 132.91-571.18 nM for BChE. In the last years, inhibition of the CA enzyme has been considered as a promising factor for pharmacologic intervention in a diversity of disturbances such as obesity, glaucoma, cancer, and epilepsy.

Keywords: N-heterocyclic carbene precursors; acetylcholinesterase; butyrylcholinesterase; carbonic anhydrase; enzyme inhibition; α-glycosidase.