(Salen)Mn(III) Compound as a Nonpeptidyl Mimic of Catalase: Theoretical Study of the Reaction Mechanism and Comparison with (Salen)Mn Catalyzed Epoxidation Activities
Y.G. Abashkin and S.K. Burt
National Cancer Institute, US
(salen)Mn, catalase mimic, catalytic mechanism, dft calculations
Catalase mimics can be used as therapeutic agents against oxidative stress in treatment of many diseases including Alzheimer’s disease, stroke, heart disease, aging and cancer. (Salen)Mn(III) compounds have been proven to be promising as synthetic antioxidants that, in particular, dismutate H2O2 resulting in two water molecules and oxygen. For the first time we have performed quantum chemical investigation of catalase activity of (salen)Mn(III) biomimetic compound using the density functional theory method. A ping-pong mechanism approach has been considered to describe the H2O2 dismutation reaction. Part I of the dismutation reaction – converting a peroxide molecule into a water molecule with simultaneous oxidation of the metal atom of the catalyst–can be done quite effectively at the Mn catalytic center. To act as catalytic scavengers of hydrogen peroxide, the oxomanganese salen complexes have to be deoxidized during part II of the dismutation reaction. Two possible reaction routes for the second part of the dismutation reaction: the top and the side substrate approach routes are discussed. Our findings on the reaction dismutation mechanism could be the starting point for improvement of salen–manganese complexes as synthetic catalytic scavengers of reactive oxygen species.
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Nanotech 2005 Conference Program Abstract