[Comparative study of the effect of daunorubicin and its nitroxyl derivative on in vitro function of rat liver mitochondria].

The effect of rubomycin (daunorubicin) and its nitroxyl derivative, ruboxyl, on respiration and oxidative phosphorylation of the rat liver mitochondria was comparatively studied. It was shown that ruboxyl had a more pronounced uncoupling effect than rubomycin, especially during respiration in the presence of the glutamate mixture with malate. Unlike rubomycin, ruboxyl in concentrations of 0.05 to 0.5 mM induced stimulation under metabolic conditions rather than respiration. When the antibiotic concentration increased ruboxyl started to inhibit the respiration as compared to the control and the inhibition level appeared to be higher than that induced by rubomycin. Possible mechanisms for decreasing rubomycin toxicity by its modification with the nitroxyl radical are discussed.