Abstract
Benzimidazole derivatives exhibited a broad range of biological activities, e.g., antimicrobial, antiviral, anthelmintic, anti-inflammatory, anticancer and as an anti-ulcer/proton pump inhibitor. Keeping in view the large number of reported drugs containing benzimidazole moiety on one hand and sulfonamide on the other hand, a small series of N-tosyl benzimidazoles (4a-e) have been synthesized. The present work describes the synthesis, characterization and bio-evaluation of five new N-tosyl benzimidazoles with the objective to develop new compounds with improved anticancer, antibacterial and urease inhibitory activities. The substituted 1,2-phenylenediamines in the first step were condensed with aliphatic carboxylic acids to synthesize the substituted benzimidazoles. In the second step the tosyl chloride was reacted with substituted benzimidazoles in basic conditions to afford the title N-tosyl benzimidazoles (4a-e). The screening for their antitumor activities was performed against Agrobacterium tumefaciens by following the potato disc tumor assay. The compound (4e) exhibited excellent antitumor activity with IC50 values 474.45 mu gml(-1) compared to other synthesized compounds. Antibacterial activity results revealed that compounds 4d and 4e having methyl and ethyl substitution respectively at the imidazole ring showed excellent zone inhibition against both gram positive and gram negative strains. The urease inhibitory activity results showed that derivative 4e exhibited highest potential to inhibit the urease enzyme compared to all other derivatives. Based upon our investigation it is proposed that compound (4e) may serve as lead structure to design more potent biological active compounds having multitargets inhibition activities.