(Salen)Mn(Ⅲ) Compound as a Nonpeptidyl Mimic of Catalase: Theoretical Study of the Reaction Mechanism and Comparison with (Salen)Mn Catalyzed Epoxidation Activities

摘要

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 H_2O_2 resulting in two water molecules and oxygen. For the first time we have performed quantum chemical investigation of catalase activity of (salen)Mn(Ⅲ) biominetic compound using the DFT method. A ping-pong mechanism approach has been considered to describe the dismutation reaction. Part Ⅰ of the reaction -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 reaction. Two possible reaction routes for the second part of the reaction: the top and the side substrate approach routes are discussed. Our findings could be the starting point for improvement of salen-manganese therapeutic and catalytic properties.