SYNTHESIS AND BIOLOGICAL EVALUATION OF 2-SUBSTITUTED PHENYL-1-(SUBSTITUTED PIPERAZIN-1-YL) METHYL)-1H-BENZO[D]IMIDAZOLES

A series of biologically active benzimidazole derivatives (2a-2n) was synthesized by the reaction of o-phenylenediamine with the derivatives of benzoic acid in presence of 4N-HCl followed by the reaction with piperazine and formaldehyde to undergo Mannich reaction. The structures of all the synthesized Mannich bases were characterized by UV, FTIR, 1H NMR, mass spectroscopy and elemental analysis. The compounds were evaluated for their anthelmintic activity by the identification of paralyzing and death time by using mebendazole as standard in the concentration of 2 mg/ml. The compounds 2a, 2b, 2e and 2h were found to be most potent for anthelmintic activity. All the compounds were also evaluated for antibacterial activity against gram-positive bacterial strains like Bacillus subtilis and Streptococcus aureus, and gram-negative bacterial strains like Escherichia coli and Pseudomonas aeruginosa. The study was performed through disc diffusion method by using Ciprofloxacin as standard in the concentration of 50µg/ml. The compounds 2e, 2h, 2k, 2l and 2m were found to possess significant antibacterial activity.