Synthesis, Characterization and Antimicrobial Activity of Cu (II), Co (II) and Ni (II) Histidine Complexes

Abstract

Ternary complexes of histidine amino acid (Schiff base) were synthesized, characterized and tested against multi-drug resistant pathogens. The metal ion centers included Cu (II), Ni (II) and Co (II). These complexes were characterized using physico-chemical and spectroscopic analytical methods. All the complexes are found to be considerably soluble in both polar and non-polar solvents including methanol, ethanol, butanol, acetone, ethyl acetate, and benzene and di ethyl-ether. Electronic Absorption Studies using FT-IR spectrophotometer revealed ν (O-H), ν (C=O), ν (C=N), ν (M -N) and ν (M-O) occurred between 3410 - 3417, 1751 - 1753, 1519 – 1521, 671 – 678, 439 – 470 cm-¹ respectively in complexes and ligand. UV-Visible was further used to elucidate the complexes resulting in transitions characteristics of the ligand and complexes. The Schiff base showed no antimicrobial activity at various therapeutic concentrations. However, the metal complexes exhibited broad spectrum antibiotic activities against the multi-drug resistant pathogens at minimum inhibitory concentration (MIC ≤ 200 µg/ml). The metal complexes showed strong activity against the isolates at medium and high concentrations, the bacteria strains included E.coli, P. aeruginosa, S. typhi and S. aureus and the fungi strains of Candida albicans, Aspergillus flavus and Aspergillus niger. The bioactivity recorded against these multi drug resistant pathogens indicates the potentials of these complexes for further therapeutic studies.

Keywords: Histidine complex, synthesis, characterisation, antimicrobial activity, pathogens.