Anthracycline Antibiotic-stimulated Superoxide, Hydrogen Peroxide, and Hydroxyl Radical Production by NADH Dehydrogenase1

This study investigated the effect of the anthracycline anti biotics on oxygen radical metabolism by cardiac mitochondria! reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase [NADH:(acceptor)oxidoreductase, EC 1.6.99.3], Superoxide formation by NADH dehydrogenase after anthracycline treatment appeared to follow saturation kinetics with an apparent Km of 167.3, 73.3, 64.0, or 47.6 (iM for doxorubicin, daunorubicin, rubidazone, or aclacinomycin A, respectively. Superoxide for mation by NADH dehydrogenase after doxorubicin treatment occurred with a pH optimum of 7.6 and was accompanied by the production of hydrogen peroxide. Furthermore, drug-related hydroxyl radical generation was detected in this enzyme system by the evolution of methane gas from dimethyl sulfoxide. Hy droxyl radical production proceeded only in the presence of Superoxide aniÃ3n,hydrogen peroxide, and trace amounts of iron or a chetate of iron and ethylenediaminetetraacetate and thus was probably the by-product of a transition metal-catalyzed Haber-Weiss reaction. The antitumor agents mitoxantrone and actinomycin D did not significantly enhance reactive oxygen metabolism by NADH dehydrogenase. These results suggest that the specific activation of the an thracycline antibiotics to free radicals by NADH dehydrogenase leads to the formation of a variety of reactive oxygen species that may contribute to the mitochondria! toxicity of these drugs.