Substituent Effects upon the Catalytic Activity of Aromatic Cyclic Seleninate Esters and Spirodioxyselenuranes That Act as Glutathione Peroxidase Mimetics

Substituent effects were studied in a series of aromatic cyclic seleninate esters and spirodioxyselenuranes that function as mimetics of the antioxidant selenoenzyme glutathione peroxidase. The methoxy-substituted selenurane proved the most efficacious catalyst for the reduction of hydrogen peroxide with benzyl thiol, and the reaction rates were enhanced for both classes by electron-donating substituents. Hammett plots indicated rho = -0.45 and -3.1 for the seleninates and selenuranes, respectively, suggesting that oxidation at Se is the rate-determining step in their catalytic cycles.