Inhibition of selenite-catalyzed superoxide generation and formation of elemental selenium (Se°) by copper, zinc, and aurintricarboxylic acid (ATA)

Selenite catalyzes the oxidation of glutathione (GSH) with the subsequent generation of superoxide (O₂·^-). Copper, zinc, and aurintricarboxylic acid (ATA) were tested for their ability to inhibit both the selenite-catalyzed generation of superoxide and the conversion of selenite to elemental selenium (Se°). As measured by lucigenin-dependent chemiluminescence (CL), copper, zinc, and ATA were shown to inhibit significantly (P < 0.05) selenite-catalyzed CL in a concentration-dependent manner. The inhibition of the selenium-catalyzed generation of superoxide by copper(II) was greater than by either zinc or ATA. In addition, copper, zinc, and ATA all inhibited the conversion of selenite to Se°. Inhibition of selenite-catalyzed CL by copper, zinc, and ATA is believed to occur as the result of inhibition of Se^2- and/or GSSe^-, the catalytic selenopersulfide anion of GSH.