Novel Benzimidazole linked piperidine derivatives screened for antibacterial and antioxidant properties with Density Functional and Molecular Mechanic tools

Abstract

In the present work, the scope for obtaining an active and less toxic anti-microbial and antioxidant agent, was explored to synthesize novel benimidazole semicarbazide derivatives (F1-F5) by conventional method. A novel series of 1-(substituted benzylidene)-4-(4-(3-oxo-3-(1-(piperidin-1-ylmethyl)-1Hbenzoimidazol-2-yl) prop-1-enyl) phenyl) semicarbazide F1-F5 were synthesized from o-phenylenediamine by using multi-step synthesis. IR, 1H NMR, 13C NMR Mass spectroscopy and elemental analysis data of the synthesized compounds are found to be in accordance with the assigned structures. Under DFT, B3LYP/6311G method was used to investigate novel compounds, their electronic characteristics were evaluated using the same. All the title compounds were evaluated for their in-vitro anti-microbial activity against three bacteria and three fungi by the agar well diffusion method at three different concentrations and for antioxidant activity by the DPPH (2,2-diphenyl-1-picrylhydrazyl) Scavenging method. Among the synthesized compounds, F2 and F4 showed significant antibacterial activity, whereas compound F3 showed significant antifungal activity. Compound F1 showed moderate to good antibacterial and antifungal activity against selected strains with the SAR study. It was observed that the compounds having electron withdrawing moiety exhibited better antibacterial activity than compounds having electron donating ones, whereas in antifungal it was viceversa. Out of five compounds, F2 exhibited the most potent antibacterial and antifungal activity, while F3 exhibited potent antioxidant activity. As a result, the compounds F2 and F3 could serve as pilot molecules for the further development of a novel class of antimicrobial agents.