The Antimicrobial Activity of Mononuclear Ruthenium(II) Complexes Containing the dppz Ligand

Liu, X, Sun, B, Kell, REM, Southam, HM, Butler, Jonathan, Li, X, Poole, RK, Keene, FR and Collins, JG (2018) The Antimicrobial Activity of Mononuclear Ruthenium(II) Complexes Containing the dppz Ligand. ChemPlusChem, 83 (7). pp. 643-650. ISSN 2192-6506

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Abstract

The cis‐α isomer of [Ru(bb7)(dppz)]2+ (dppz=dipyrido[3,2‐a:2′,3′‐c]phenazine; bb7=bis[4(4′‐methyl‐2,2′‐bipyridyl)]‐1,7‐alkane) has been synthesised. The minimum inhibitory concentrations and the minimum bactericidal concentrations of [Ru(bb7)(dppz)]2+ and its parent complex [Ru(phen)2(dppz)]2+ (phen=1,10‐phenanthroline) were determined against a range of bacteria. The results showed that both ruthenium complexes exhibited good activity against Gram‐positive bacteria, but [Ru(bb7)(dppz)]2+ showed at least eightfold better activity against the Gram‐negative bacteria than [Ru(phen)2(dppz)]2+. Luminescence assays demonstrated that [Ru(bb7)(dppz)]2+ accumulated in a Gram‐negative bacterium to the same degree as in a Gram‐positive species, and assays with liposomes showed that [Ru(bb7)(dppz)]2+ interacted more strongly with membranes than the parent [Ru(phen)2(dppz)]2+ complex. The DNA binding affinity for [Ru(bb7)(dppz)]2+ was determined to be 6.7 × 106 m−1. Although more toxic to eukaryotic cells than [Ru(phen)2(dppz)]2+, [Ru(bb7)(dppz)]2+ exhibited greater activity against bacteria than eukaryotic cells.