Copper-zinc metal complex exhibiting bactericidal and antibiofilm activity by membrane damage and quorum sensing inhibition

Abstract

A hetero di nuclear complex [Zn(o-phen)LCu(OAc)] (K3 compound), where, H3L = o-HOC6H4C(H)=N−NH−C(OH)=N−NC(H)−C6H4OH-o, o-phen = 1,10-phenanthroline, and OAc = CH3COO− was synthesized. The Schiff base ligand in its keto form used for synthesis was derived from the condensation of salicylaldehyde and carbohydrazide, however, the Schiff base was found to coordinate in its enol form (L3−) as it was confirmed from the reported crystal structure of K3 compound. The K3 compound displayed significant antibacterial activity in both planktonic and biofilms of the test organisms, Pseudomonas aeruginosa and Staphylococcus aureus. The anti-quorum sensing activity was investigated in P. aeruginosa to determine the effect of the K3 compound on bacterial chemo-signaling networks that collectively control bacterial virulence, including twitching motility, swarming motility, rhamnolipids, pyocyanin and, exopolysaccharide production. The synthesized novel hetero Zn(II)/Cu(II)-based di-nuclear complex [Zn(o-phen)LCu(OAc)], K3 compound exhibited potent antibacterial and antibiofilm properties against P. aeruginosa and S. aureus, with significant biofilm disruption, inhibition, and anti-quorum sensing effects, making it a promising candidate for further investigation as a potential antibacterial agent.