Synthesis and characterization of bismuth(III) complex with an EDTA-based phenylene ligand and its potential as anti-virulence agent

A new acyclic bismuth complex (Bi-edtabz) was synthesized from a mixture of solutions of the ligand (EDTA-based phenylene) and bismuth under acidic conditions. Its anti-virulence properties were evaluated against Escherichia coli O157: H7, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enterica sub. enterica serovar Typhimurium and Staphylococcus aureus. The bismuth complex was characterized by NMR, UV-Vis, FTIR, ESI/MS and TG. Furthermore, Bi-edtabz complex at 0.25–1 mM presented better antibiofilm properties against E. coli O157: H7 and S. aureus with values of biomass reduction of 30.1–57.1% and 37.8–55.5%, respectively, compared with the ligand edtabz. While biofilm formation of L. monocytogenes, P. aeruginosa and Salmonella Typhimurium was most impaired by edtabz (biomass reduction of 66.1–100%, 66.4–88.0% and 50.9–67.1%), respectively. Additionally, Bi-edtabz inhibited the swimming motility of E. coli O157: H7 (12.5%) and colony spread of S. aureus (47.2%) at 1 mM and inhibited violacein production, a quorum-sensing related pigment of the biosensor strain Chromobacterium violaceum. Hence, edtabz and the Bi-edtabz complex can be used as novel anti-virulence agents against pathogenic bacteria.