Carbon monoxide releasing molecules offer new opportunities for treating disease.

Carbon monoxide (CO) has a variety of beneficial therapeutic effects including anti-inflammatory properties. Yet, CO binds to haemoglobin in the blood and is lethal in high doses. With this in mind, Brian Mann at the University of Sheffield, UK, is examining CO-releasing molecules (CORMs) as an alternative to treating a patient with the gas. CORMs 'could allow CO to be released locally within the body,' he explained.

CORM-3 is a ruthenium complex that releases CO in vivo. The complex was designed as a water-soluble version of previously-known CORMs and protects heart cells from damage during transplantation in animal experiments. But identifying the species present under physiological conditions is a crucial step in creating new pharmaceuticals and CORM-3 has shown complicated solution chemistry. Now Mann and his colleagues have brought the concept of CORM-based drugs a step closer by identifying the structure of CORM-3 and the related complexes formed in solution at physiological pH.

CORM-3 has complex solution chemistry

The researchers showed that in CORM-3, ligands form an octahedral complex around the ruthenium atom, with the carbonyls lying on one face of the octahedron. Mann said that modifying the ligand system could potentially 'allow targeted release of CO in the future.'

Enzo Alessio, an expert in biologically-active transition metal complexes at the University of Trieste in Italy, said the research was 'an excellent example of how basic coordination chemistry can provide valuable data for understanding biologically relevant processes.'

Russell Johnson