Karpin, George W.Morris, David M.Ngo, Mai T.Merola, Joseph S.Falkinham, Joseph O. III2015-11-172015-11-172015-06Med.Chem.Commun.,2015,6,1471–1478DOI: 10.1039/c5md00228ahttp://hdl.handle.net/10919/64167Pentaalkylcyclopentadienyl (Cp*R) iridium (Ir) and cobalt (Co) 1,2-diamine complexes were synthesized. Susceptibility of Staphylococcus aureus and recent patient methicillin-resistant S. aureus (MRSA) isolates to the transition metal–diamine complexes were measured by broth microdilution and reported as the MIC and MBC. Hemolytic activities of the transition metal-complexes as well as toxicity toward Vero cells were also measured. The transition metal complex of Cp*RIr with cis-1,2-diaminocyclohexane, had strong antibi- otic activity against S. aureus and MRSA (MIC = 4 μg mL−1, MBC = 8 μg mL−1) strains and killed 99% of S. aureus cells in 6 hours. Stronger antibiotic activity was associated with the presence of octyl linked to the cyclopentadienyl group and cyclohexane as the diamine backbone. Activity was greatly diminished by tri- or tetramethylation of the nitrogen of the diamine. A cyclopentadienylcobalt complex of cis-1,2-diamino- cyclohexane also showed significant anti-microbial activity against both S. aureus and MRSA strains. The absence of hemolytic activity, Vero cell cytotoxicity and the significant anti-microbial activity of several members of the family of compounds reported suggest this is an area worth further development.application/pdfen-USCreative Commons Attribution-NonCommercial-NoDerivs 3.0 United StatesStaphylococcus aureusMRSAAntibioticAntimicrobialTransition metal complexArticle - Refereedhttps://doi.org/10.1039/c5md00228a