Enhancement of antibacterial activity by a copper(II) and zinc(II) in chelation with ethylenediaminetetra-acetic acid and urea complex

Although it is unclear how Zn2+ cooperates with Cu2+ in synergistic antibacterial activity, a 1:10 ratio of Cu2+/Zn2+ atoms and ethylenediaminetetra-acetic acid and urea ligands can be used to form a chelation complex containing Cu2+ and Zn2+. This study investigated the effects of the combination of Cu2+ and Zn2+ in chelation with EDTA and urea. The results were compared with the outcomes of either copper or zinc alone against gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) bacteria. The antibacterial activity was determined through MICs, disc diffusion method, and bacterial cell growth curves. In addition, bacterial destruction by this chelation complex has been observed through SEM images. The presence of copper ion and zinc ion inside the bacterial cells has been proved through EDS measurements. The obtained results allowed us to draw conclusions that the use of both Cu2+ and Zn2+ in a chelation complex with EDTA and urea enhances the antimicrobial activity against these bacteria. The bacterial inhibition of this complex was stronger than that of Cu2+ alone chelated with EDTA or CuSO4 solution by approximately 100-fold for S. aureus and 20-fold for E. coli. © 2022, Institute of Chemistry, Slovak Academy of Sciences.