Lucigenin (Bis-N-methylacridinium) as a mediator of superoxide anion production

Lucigenin (bis-N-methylacridinium) (LUC(2+)) has frequently been used for the luminescent detection of O-2(-). In fact, the pathway leading to this luminescence requires univalent reduction of Luc(2+) to LucH(.+) followed by formation of an unstable dioxetane by reaction of LucH(.+) with O-2(-). It is now shown that LucH(.+) rapidly autooxidizes and so produces (-)(2). Luc(2+) can thus mediate O-2(-) production in systems, such as glucose plus glucose oxidase, in which there is ordinarily no O-2(-) production. Luc(2+) luminescence can thus be used as the basis for assaying superoxide dismutase activity but should not be used for measuring, or even detecting, O-2(-). (C) 1997 Academic Press, Inc.