WAKE FOREST UNIVERSITY
Grant: $324,069 - National Institutes of Health - Jul. 17, 2009
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Award Description: Description of Overall Purpose-The long-term goal of the proposed research is to further develop and understand the nitric oxide (NO) and nitroxyl (HNO), the one-electron reduced form of NO, producing reactions of C-nitroso compounds (1, Scheme 1). Some C-nitroso compounds exist as stable entities and other unstable versions can be generated from hydroxyurea and related species. Hydroxyurea has gained clinical approval for the treatment of sickle cell disease and exciting work over the last few years reveals important roles for NO in both the pathophysiology and treatment of this and other hemolytic diseases. Our previous work identifies C-nitroso compounds and nitroxyl (HNO) as key components in NO formation from hydroxyurea While nitric oxide plays important roles in the maintenance of normal blood pressure, memory and learning, and the immune response, the biological function of nitroxyl (HNO) remains less well understood. Increasing extensively reviewed evidence highlights the biological importance of HNO and its distinct biological responses compared to NO. At this time, the lack of structurally diverse and reliable HNO donors severely limits the further characterization of HNO chemistry and biology. The studies described in this proposal address new strategies for HNO release, the interactions of HNO with biochemical targets and the biological/physiological outcomes of these reactions. The achievement of these research goals will be approached through the sequential combination of chemical synthesis and characterization, evaluation and kinetic analysis of NO or HNO release, biochemical and biophysical analysis with selected proteins and physiological studies with cardiac tissue. Expected Outcomes-The first specific aim of this proposal is to determine whether structural derivatives of C-nitroso compounds (2, acyloxy nitroso compounds) act as NO/HNO donors by preparing and characterizing these compounds as NO/HNO donors. Preliminary results show these stable compounds cleanly release HNO upon ester hydrolysis and relax pre-constricted rat aortic rings showing their ability to elicit a biological response. The proposed synthesis of these molecules follows a modular approach allowing a wide structural range of compounds with modified targeting or NO or HNO release properties. The second specific aim is to determine the interaction of these new NO/HNO donors with biological target molecules and tissues, including hemoglobin, soluble guanylate cyclase, catalase, thiol-containing proteins, the peroxisomal proliferator-activated receptor gamma (PPAR?), pre-constricted blood vessels and cardiac tissue. Preliminary work defines the reactivity of these acyloxy nitroso compounds to react with and oxidize thiol groups in both HNO dependent and independent fashions. Other work shows the reactivity of these HNO donors with specific thiol residues in rat cardiac muscle tissue. These research goals will be further pursued through the sequential combination of chemical synthesis and characterization, evaluation and kinetic analysis of NO or HNO release, biochemical and biophysical analysis with selected proteins and physiological studies with cardiac tissue.
Project Description: During this quarter, a total of 6 structurally new acyloxy nitroso compounds were prepared and characterized. These compounds each released HNO similar to previous materials and a manuscript describing these compounds is in preparation. The reaction of acyloxy nitroso compounds with thiols has also been examined kinetically and for product formation. These results show that thiols can directly react with the acyloxy nitroso compounds and indicates an HNO independent pathway. A manuscript is in preparation regarding these results. The reaction of these compounds with thiol containing proteins is being pursued and experiments in collaboration with Dr. Nazareno Paolocci (Johns Hopkins University) show that these compounds specifically modify thiols in rat cardiac tissue. These results provide information regarding the mechanism of action of these agents in controlling muscle contractility. Abstracts have been submitted to the American Chemical Society and the American Heart Association regarding the presentation of these results. Financially, funds have been used to upgrade existing UV and HPLC equipment and purchase a new UV spectrophotometer. An offer of employment to a new post-doctoral researcher has been made. As described in the award description field
Jobs Summary: Not applicable (Total jobs reported: 0)
Project Status: Less Than 50% Completed
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