Mulla, R.S. and Beecroft, M.S. and Pal, R. and Aguilar, J.A. and Pitarch-Jarque, J. and García‐España, E. and Lurie-Luke, E. and Sharples, G.J. and Williams, J.A.G. (2018) 'On the antibacterial activity of azacarboxylate ligands : lowered metal ion affinities for bis-amide derivatives of EDTA do not mean reduced activity.', Chemistry : a European journal., 24 (28). pp. 7137-7148.
EDTA is widely used as an inhibitor of bacterial growth, affecting the uptake and control of metal ions by microorganisms. We describe the synthesis and characterisation of two symmetrical bis‐amide derivatives of EDTA, featuring glycyl or pyridyl substituents: AmGly2 and AmPy2. Metal ion affinities (logK) have been evaluated for a range of metals (Mg2+, Ca2+, Fe3+, Mn2+, Zn2+), revealing less avid binding compared to EDTA. The solid‐state structures of AmGly2 and of its Mg2+ complex have been determined crystallographically. The latter shows an unusual 7‐coordinate, capped octahedral Mg2+ centre. The antibacterial activities of the two ligands and of EDTA have been evaluated against a range of health‐relevant bacterial species, three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and a Gram positive (Staphylococcus aureus). The AmPy2 ligand is the only one that displays a significant inhibitory effect against K. pneumoniae, but is less effective against the other organisms. AmGly2 exhibits a more powerful inhibitory effect against E. coli at lower concentrations than EDTA (<3 mm) or AmPy2, but loses its efficacy at higher concentrations. The growth inhibition of EDTA and AmGly2 on mutant E. coli strains with defects in outer‐membrane lipopolysaccharide (LPS) structures has been assessed to provide insight into the unexpected behaviour. Taken together, the results contradict the assumption of a simple link between metal ion affinity and antimicrobial efficacy.
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||https://doi.org/10.1002/chem.201800026|
|Publisher statement:||This is the peer reviewed version of the following article: Mulla, R.S., Beecroft, M.S., Pal, R., Aguilar, J.A., Pitarch-Jarque, J., García‐España, E., Lurie-Luke, E., Sharples, G.J. & Williams, J.A.G. (2018). On the antibacterial activity of azacarboxylate ligands: lowered metal ion affinities for bis-amide derivatives of EDTA do not mean reduced activity. Chemistry - A European Journal 24(28): 7137-7148, which has been published in final form at https://doi.org/10.1002/chem.201800026. This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving.|
|Date accepted:||12 February 2018|
|Date deposited:||14 February 2018|
|Date of first online publication:||23 March 2018|
|Date first made open access:||23 March 2019|
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