Synthesis, characterization and crystal structure of 2-(4-hydroxyphenyl)ethyl and 2-(4-nitrophenyl)ethyl Substituted Benzimidazole Bromide Salts: Their inhibitory properties against carbonic anhydrase and acetylcholinesterase

This paper reports the synthesis of 2-(4-hydroxyphenyl)ethyl and 2-(4-nitrophenyl)ethyl substituted benzimidazolium salts. The benzimidazolium salts were synthesized by N-substituted benzimidazolium and aryl halides. The 2-(4-hydroxyphenyl)ethyl and 2-(4-nitrophenyl)ethyl substituted benzimidazolium salts were characterized by using 1H NMR, 13C NMR, FT-IR spectroscopy and elemental analysis techniques. Molecular and crystal structure of the complex 2d and 3d were obtained by single-crystal X-ray diffraction method. Additionally, The enzyme inhibition activities of the benzimidazolium salts were investigated. These 2-(4-hydroxyphenyl)ethyl and 2-(4-nitrophenyl)ethyl substituted benzimidazolium salts (1, 2a-g, and 3a-f) showed good inhibitory action against acetylcholinesterase (AChE), and human (h) carbonic anhydrase (CA) isoforms I, and II. Ki values for AChE were in range of 5.97 ± 0.56–23.15 ± 3.98 nM. On the other hand, the hCA I, and II isoenzymes were effectively inhibited by these compounds, with Ki values in the range of 17.33 ± 4.55–99.23 ± 44.91 nM for hCA I, and 33.98 ± 3.43–113.23 ± 39.31 nM for hCA II, respectively.