Session Speaker
Nitric oxide donors based on ruthenium complexes. Cytotoxical, photobiological and pharmacological aspects
Zumira A. Carneiro, Tassiele Heinrich, Juliana C. B. Moraes, Antonio C. Tedesco, Lusiane, M. Bendhack and Roberto S. da Silva
Brazil

Nitric oxide (NO) donors produce NO-related activity when applied to biological systems. Among its diverse functions, NO has been implicated in vascular smooth muscle relaxation and neoplasic cells. Despite the great importance of NO in biological systems, its pharmacological and physiological studies have been limited due to its high reactivity and short half-life. In this presentation we will focus on our recent investigations of nitrosyl ruthenium complexes as NO-delivery agents and their effects on vascular smooth muscle cell relaxation and cytotoxical activity. The high affinity of ruthenium for NO is a marked feature of its chemistry. The main signaling pathway responsible for the vascular relaxation induced by NO involves the activation of soluble guanylyl-cyclase, with subsequent accumulation of cGMP and activation of cGMP-dependent protein kinase. The cytotoxical effect of nitrosyl ruthenium complexes was also observed under light irradiation. Under continuous photolysis at 675 nm, liposomal zinc phthalocyanine associated with nitrosyl ruthenium complex showed the detection and quantification of nitric oxide (NO) and singlet oxygen release. Synergistic action of both photosensitizers and the nitrosyl ruthenium complex results in the production of reactive oxygen species and reactive nitrogen species, which is a potent oxidizing agent to many biological tissues, in particular neoplasic cells.