Antibacterial Fischer carbenoid CO-releasing molecules

Abstract

CO releasing molecules (CORMs) of transition metal carbonyl complexes are emerging as a new interdisciplinary advance of inorganic chemistry, biological medicine and materials chemistry. In this paper, new ionic Fischer carbene carbonyl complexes were devised, in which Cr, Mo and W metals as metallic center carried five CO whilst the quaternary ammonium finely tuned the water solubility of Fc-CORMs. The myoglobin assays showed that one Fc-CORM released at least two molecules of carbon monoxide in well-controlled fashion under physiological conditions. The structure-releasing correlation revealed that the central metal was the key factor governing their carbon monoxide release behavior. The CO release rate of Fc-CORM-Mo (2a~2e) is quicker than Fc-CORM-Cr (1a~1e), much faster than Fc-CORM-W (3a~3e). The antibacterial activity test found that Fc-CORM (1b) with medium CO release rate effectively inhibited the growth and survival of Escherichia coli, with an minimal inhibitory concentration (MIC) value of 30 μmol/L. As for drug-resistant bacteria, Fc-CORM (2a~2e) and Fc-CORM (3a~3e) showed bactericidal activity. Mechanism study indicated that the antibacterial activity relied on the CO release rate of Fc-CORMs.