Lucigenin (Bis-N-methylacridinium) as a Mediator of Superoxide Anion Production

Lucigenin (bis-N-methylacridinium) (Luc2+) has frequently been used for the luminescent detection of O−2. In fact, the pathway leading to this luminescence requires univalent reduction of Luc2+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 O−2. Luc2+can thus mediate O−2production in systems, such as glucose plus glucose oxidase, in which there is ordinarily no O−2production. Luc2+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.