Design, synthesis, characterization and anti-inflammatory activity of some novel Benzimidazole derivatives

Abstract

A novel series of benzimidazole derivatives were synthesized through modifying the N-1 hydrogen of 2-substituted benzimidazoles with primary and/or secondary amines in ethanol yielded the corresponding N-Mannich bases (SR). The synthesized compounds were elucidated by UV, IR, ¹H NMR and Mass spectral analysis. In IR spectra, all the compounds were showed above 3100 cm^-1 due to N-H stretching vibration and in SR, showed the region of 1312 – 1320 cm^-1 due to presence SO stretching of sulphonamide group. In ¹H NMR spectra of N-mannich bases showed well resolved peaks at 7.10-7.64 ppm as a result of Ar-H, at 4.57-4.60 ppm due to two protons in SO₂NH₂ group and at 1.13-1.15 ppm due to one proton in NH group of piperazine. The final compounds were evaluated for their anti-inflammatory activity by HRBC membrane stabilization method and Carrageen in induced rat hind paw edema. The synthesized derivative (SR₉) exhibited very good significant anti-inflammatory activity.