Antibacterial potentials and DNA study of cobalt(II) complexes containing aminophenol Schiff base moiety

Abstract

The present study was carried out to investigate the effect of substituent groups on the antibacterial activities of 2-aminophenol Schiff bases and their cobalt (II) complexes. Development of new compounds with potential effects against pathogenic organisms has become necessary due to the increase in microbial resistance reported for existing antiseptics and disinfectants. In line with this, new cobalt (II) complexes with Schiff bases derived from 2-aminophenol and p-substituted benzaldehydes were synthesized. The compounds were characterized using elemental analysis, mass spectrometry, atomic absorption spectroscopy, electrospray ionization mass spectrometry, infrared spectroscopy, 1H NMR and electronic absorption spectroscopy. Results indicate that all metal complexes had a 1:2 metal ligand ratio with magnetic moments characteristic of tetrahedral geometry around the metal ion. The Schiff bases and their metal complexes were screened for in-vitro antibacterial activities against 6 human pathogenic bacteria usually found around the hospitals and homes; Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 19582), Bacillus cereus (10702), Enterococcus faecalis (ATCC 29212) and Kribsella pneumonia (ATCC 10031) with ampicillin used as the reference compound. DNA binding study using calf thymus DNA revealed intercalative mode of activity. The result showed that Schiff bases exhibited moderate inhibitory activity against the tested microorganisms while Schiff base metal complexes exhibited higher antibacterial activity when compared to ampicillin. Our results indicate that these complexes can be employed as active ingredients in development of broad-spectrum antibacterial agents.