Synthesis, characterization, molecular docking, and antibacterial evaluation of mixed-ligand transition metal complexes of Cefotaxime and Omeprazole

Five new mixed ligand complexes of Zn(II), Ni(II), Co(II), Cu(II) and Mn (II) were synthesized, with Cefotaxime as primary and Omeprazole as secondary ligand and were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy, and UV-visible spectroscopy. The antibacterial testing against E. coli and S. aureus demonstrated a strong dependence on the coordinating metal ions in terms of biological activity. Zn(II) and Cu(II) complexes proved to exhibit more effective inhibitory action against S. aureus than the reference antibiotic cefotaxime, while the Co(II) complex was moderately active and the Ni(II) complex had relatively poor activity. As for E. coli, all tested complexes exhibited weak to moderate activity, but the Zn(II) complex was the most active one among those examined, although still less active than the initial antibiotic. The molecular docking analysis also confirmed the findings of the experiments, demonstrating high binding capacity towards both bacteria and thus explaining higher antibacterial efficiency. Overall, these findings suggest that the modification of cefotaxime through the formation of mixed ligand metal complexes, particularly with Zn(II), can influence its antibacterial spectrum and potency. This approach may provide a promising pathway for the development of new antimicrobial agents aimed at addressing the growing problem of bacterial resistance. Further investigations, including mechanistic studies and in vivo evaluations, are recommended to explore the therapeutic potential of these complexes.