Antimony and bismuth as antimicrobial agents

There is an emerging interest in the application of metal complexes in the treatment of microbial infections and colonization. Their unique modes of action and the difficulty that microbes face in evolving mechanisms for resistance toward metal complexes, makes them attractive. Metal complexes offer a way to incorporate a diverse range of ligands and therefore easily tune physico-chemical properties, which in turn can affect the overall behavior of the complex in a biological system. For more than a decade, we have synthesized and characterized a range of bismuth and antimony complexes in the +III and +V oxidation states and evaluated their efficacy toward the treatment of Leishmania or bacteria, including but not limited to: Helicobacter pylori, methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus and Escherichia coli. In many cases these novel complexes outperform the current medicinal compounds employed. There is still work to be done to understand the relationship between the chemical structure of metal complexes and their corresponding antimicrobial activity. We have compiled recent results in the area of metal complexes against microbes, to uncover some of the trends related to antimicrobial activity.