Diastereomeric bactericidal effect of Ru(phenanthroline)(2)dipyridophenazine

Journal article, 2016

Metal susceptibility assays and spot plating were used to investigate the antimicrobial activity of enantiopure [Ru(phen)(2)dppz](2+) (phen =1,10-phenanthroline and dppz = dipyrido[3,2-a:2 ',3 '-c]phenazine) and [-bidppz(phen)(4)Ru-2](4+) (bidppz =11,11 '-bis(dipyrido[3,2-a:2 ',3 '-c]phenazinyl)), on Gram-negative Escherichia coli and Gram-positive Bacillus subtilis as bacterial models. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined for both complexes: while [-bidppz(phen)(4)Ru-2](4+) only showed a bactericidal effect at the highest concentrations tested, the antimicrobial activity of [Ru(phen)(2)dppz](2+) against B. subtilis was comparable to that of tetracyline. In addition, the -enantiomer of [Ru(phen)(2)dppz](2+) showed a 2-fold higher bacteriostatic and bactericidal effect compared to the -enantiomer. This was in accordance with the enantiomers relative binding affinity for DNA, thus strongly indicating DNA binding as the mode of action.