Antibacterial Potential of 2-(-(2-Hydroxyphenyl)-methylidene)-amino)nicotinic Acid: Experimental, DFT Studies, and...

The problems associated with antibacterial drug discovery have kept the model of antibacterial drug to an extraordinary low level. Humans carry millions of bacteria; some species of bacteria can cause infectious disease, while some are pathogenic. Infectious bacteria which can reproduce quickly in the body can cause diseases such as tuberculosis, cholera, pneumonia, and typhoid, thus arises an urgent need to develop new drugs. Herein, 2-{[(2-hydroxyphenyl)methylidene]amino}nicotinic acid was synthesized from the condensation of o-phenylenediamine and 5-nitrosalicaldehyde followed by detailed characterization by ultraviolet-visible spectroscopy, vibrational studies FT-IR, nuclear magnetic resonance (¹H-NMR, ¹³C-NMR), and gas chromatography coupled with mass spectroscopy (GC-MS). The complex synthesized was screened against selected microbes in order to establish their potential antimicrobial activity using selected known drugs as reference. From the results obtained, the Schiff base exhibited antimicrobial activity against all the tested microorganisms except Candida albicans isolate, which exhibited zero diameter zone of inhibition. The theoretical investigations of the synthesized compounds were computed using density functional theory (DFT) at the B3LYP/6-311 +  + G(d, p) level of theory and in silico molecular docking simulation. By comparing binding affinity of the studied compound and the standard drug (ampicillin), the studied compound docked against bacterial protein showed a high binding affinity for E. coli 6.6 kcal/mol and makes it effective as an antibacterial agent for E. coli.