Synthesis and Biological Evaluation of Some Substituted Benzimidazole Derivatives

Abstract

In the current research work, the title compounds 5-ethoxy-benzimidazole, were synthesized by nitration of phenacetin with concentrated nitric acid it gives N-(2-nitro-5-ethoxyphenyl) acetamide (I), which on reduction with alcohol gives 5-ethoxy-2-nitroaniline (II). Reaction of hydrazine hydrate with 5-ethoxy-2-nitroaniline produced 5-ethoxy ortho phenylene diamine (III). The substituted acids reacted with 5-ethoxy ortho phenylene diamine then yielded the corresponding 5-ethoxy-benzimidazole (IV). The identification and characterization of the synthesized compounds were carried out by Elemental analysis, melting point, Thin Layer Chromatography, FT-IR, NMR and Mass data. The synthesized compounds were evaluated for anti-tubercular activity. The test compounds were subjected to in vitro screening by the tube dilution technique employing the human virulent H37RV strain of M. tuberculosis. The test compounds IVa, IVc and IVd showed significant anti-tubercular activity against H37RV strain of Mycobacterium tuberculosis. The minimum inhibitory concentration (MIC) values were found in the range of 0.8 to 12.5 μg/mL compared with the standard drugs Isoniazid.

Keywords

• anti-tubercular activity
• <i>Mycobacterium tuberculosis</i>
• benzimidazole
• isoniazid