IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of electron-withdrawing substituents on the redox potential and catalytic activity of manganese superoxide dismutase mimics
Autor/es:
CLAUDIA PALOPOLI; CARINA BELTRAMINO; M. VICTORIA CÓVOLO; LUCIANA GHINAMO; FACUNDO FARABOLLINI; SANDRA SIGNORELLA
Lugar:
Manchester
Reunión:
Conferencia; First EuCheMS. Inorganic Chemistry Conference; 2011
Institución organizadora:
RCS
Resumen:
Superoxide dismutases (SOD) efficiently catalyze disproportionation of intracellular O2·- and provide a vital biological defense against this toxic oxygen metabolite through a mechanism involving cyclic oxidation and reduction of the metal cofactor. In MnSOD the active site contains one penta-coordinated Mn ion in a N3O2 environment. A number of mononuclear manganese-based complexes have been investigated as low molecular weight catalytic scavengers of O2·-. Among them, MnIII-salen (salen = 1,2-bis(salicylidenamino)ethane)1 and MnIII-salpn (salpn = 1,3-bis-(salicylidenamino)propane)2 are efficient SOD mimics; the last, with a longer central aliphatic chain, being more active. The reduction potential of MnSOD is fine-tuned to 0.05 V (vs SCE), a value much lower than that of the Mn3+(ac)/Mn2+(ac) couple. However, only a few studies have been performed on the ability of the ligand to control the redox potential,3 a physical property that makes the metal ion to act as catalytic center in bioinorganic SOD models. In this work we have synthethized, characterized and evaluated the redox potential and SOD activity of three new mononuclear Mn complexes with 1,3-bis(3,5-X-salicylidenamino)propane (X = F or Cl) and 1,3-bis(5-NO2-salicylidenamino)propane. The comparison of the present results with those of unsubstituted and electron-donor substituted analogues show how the aromatic substituent modulates the redox potential and affects the SOD activity of the catalyst