Photochemical Nitric Oxide Precursors: Synthesis, Photochemistry, and Ligand Substitution Kinetics of Ruthenium Salen Nitrosyl and Ruthenium Salophen Nitrosyl Complexes

Over the past decade there has been considerable interest in the chemistry and biochemistry of nitric oxide (NO, nitrogen monoxide), owing to the discovery of diverse roles in mammalian biology, examples being as a bioregulatory molecule in the blood pressure control and as a toxic agent produced in immune response to pathogens. Numerous disease states have been coupled to the under- or overproduction of NO, and as a consequence, there has been considerable interest in biomedical strategies for the selective delivery and for selective trapping of NO. For example, such NO delivery has been claimed to have potential therapeutic value in treatments of such cardiovascular events as stroke and heart attack5a as well as in treatment of cancer. In this context, ongoing studies here and elsewhere have been concerned with the preparation and mechanistic evaluation of compounds having the potential for photochemically activated NO delivery to specific physiological targets. For example, our experiments have shown that NO release induced by photolysis of iron thiol nitrosyl clusters absorbed into V79 Chinese hamster cells enhances ç-radiation killing of such cells under hypoxic (oxygen deficient) conditions.