Studies on the effects of anthracyclines on mitochondrial respiration in vitro.

Aclacinomycin, 4'-epi-doxorubicin and 4'-epi-tetrahydropyranyl-adriamycin, three novel anthraquinone derivatives under investigation for their antitumour activity, showed an inhibitory effect on the in vitro respiration of mitochondria from rat hearts. The inhibition proved to be concentration-dependent in the range 0.05 to 1.40 mM and both the NADH-oxidase and the succinate oxidase systems were affected to different extents. Among the compounds tested, 4'-epi-tetrahydropyranyl-adriamycin appeared to be the least powerful effector, requiring a significantly higher concentration for 50% inhibition of oxidation than doxorubicin and the other analogues examined.