Catalytic generation of nitric oxide from S-nitrosothiols using immobilized organoselenium species

Abstract

Novel nitric oxide (NO) generating polymeric materials possessing immobilized organoselenium species are described. These materials mimic the capability of small organoselenium molecules as well as a known selenium-containing enzyme, glutathione peroxidase (GPx), by catalytically decomposing S-nitrosothiols (RSNO) into NO and the corresponding free thiol. Model polymeric materials, e.g., cellulose filter paper and polyethylenimine, are modified with an appropriate diselenide species covalently linked to the polymeric structures. Such organoselenium (RSe)-derivatized polymers are shown to generate NO from RSNO species in the presence of an appropriate thiol reducing agent (e.g., glutathione). The likely involvement of both immobilized selenol/selenolate and diselenide species for NO production is suggested via a catalytic pathway, as deduced in separate homogeneous solution phase experiments using non-immobilized forms of small organodiselenide species. Preliminary experiments with the new RSe-polymers clearly demonstrate the ability of such materials to generate NO from RSNO species even after the contact with fresh animal plasma. It is anticipated that such NO generation from endogenous S-nitrosothiols in blood could render RSe-containing polymeric materials more thromboresistant when in contact with flowing blood, owing to NO's ability to inhibit platelet adhesion and activation.