ABSTRACT
Quinones are widely distributed in nature in both the plant and animal kingdoms. Quinones are likely to cause toxicity by one of two primary mechanisms. The first is the direct arylation of nucleophilic groups. The second involves their redox cycling and the formation of reactive semiquinones and other oxidizing species derived from molecular oxygen. There is growing evidence that DT diaphorase functions in vivo as a quinone reductase in those instances where a quinone is involved in conjugation reactions, either in biosynthetic processes or in detoxication pathways. DT diaphorase was first detected in rat liver29,30 and subsequently purified from a variety of animal tissues. Hydrogen peroxide may be the key intermediate in oxygen-dependent toxicity. The failure to adequately detoxify peroxide leads to the formation of highly reactive hydroxyl radicals through metal-catalyzed Haber-Weiss reactions.
