Synthesis and Antimicrobial Activity of Some Novel N-Mannich Bases of Substituted 2-Mercapto-1H-Benzimidazoles

The growing incidence of bacterial drug resistance enforced a new look on existing antimicrobial drugs leading to the development of new antimicrobial molecules. In view of this, a series of twenty four new [1-(N,Ndisubstituted)aminomethyl-2-(2,4-dinitrophenyl)sulphanyl-6-substituted-1H-benzimidazoles (16a-19f) were synthesized by the Mannich reaction of 2-[(2,4-dinitrophenyl)sulphanyl]-5(or 6)-substituted-1H-benzimidazoles with appropriate secondary amine and paraformaldehyde in presence of concentrated hydrochloric acid in ethanol. The newly synthesized Mannich bases were characterized by elemental analysis, IR, ¹H NMR and Mass spectral data. The Mannich bases were evaluated for antibacterial activity against gram positive and gram negative bacteria and antifungal activity against both human and phyto pathogenic fungi. Considerable number of N-Mannich bases tested has shown promising activities when compared with the standard drugs.