Human heart cytosolic reductases and anthracycline cardiotoxicity

IUBMB Life. 2001 Jul;52(1-2):83-8. doi: 10.1080/15216540252774829.


Anthracyclines are a class of antitumor drugs widely used for the treatment of a variety of malignancy, including leukemias, lymphomas, sarcomas, and carcinomas. Different mechanisms have been proposed for anthracycline antitumor effects including free-radical generation, DNA intercalation/binding, activation of signaling pathways, inhibition of topoisomerase II and apoptosis. A life-threatening form of cardiomyopathy hampers the clinical use of anthracyclines. According to the prevailing hypothesis, anthracyclines injure the heart by generating damaging free radicals through iron-catalyzed redox cycling. Although the "iron and free-radical hypothesis" can explain some aspects of anthracycline acute toxicity, it is nonetheless disappointing when referred to chronic cardiomyopathy. An alternative hypothesis implicates C-13 alcohol metabolites of anthracyclines as mediators of myocardial contractile dysfunction ("metabolite hypothesis"). Hydroxy metabolites are formed upon two-electron reduction of the C-13 carbonyl group in the side chain of anthracyclines by cytosolic NADPH-dependent reductases. Anthracycline alcohol metabolites can affect myocardial energy metabolism, ionic gradients, and Ca2+ movements, ultimately impairing cardiac contraction and relaxation. In addition, alcohol metabolites can impair cardiac intracellular iron handling and homeostasis, by delocalizing iron from the [4Fe-4S] cluster of cytoplasmic aconitase. Chronic cardiotoxicity induced by C-13 alcohol metabolite might be primed by oxidative stress generated by anthracycline redox cycling ("unifying hypothesis"). Putative cardioprotective strategies should be aimed at decreasing C-13 alcohol metabolite production by means of efficient inhibitors of anthracycline reductases, as short-chain coenzyme Q analogs and chalcones that compete with anthracyclines for the enzyme active site, or by developing novel anthracyclines less susceptible to reductive metabolism.

Publication types

  • Review

MeSH terms

  • Anthracyclines / chemistry
  • Anthracyclines / metabolism*
  • Anthracyclines / toxicity*
  • Cytosol / enzymology*
  • Doxorubicin / analogs & derivatives
  • Doxorubicin / chemistry
  • Doxorubicin / metabolism
  • Doxorubicin / toxicity
  • Free Radicals / metabolism
  • Heart / drug effects*
  • Humans
  • Iron / metabolism
  • Models, Biological
  • Myocardium / enzymology*
  • Oxidoreductases / antagonists & inhibitors
  • Oxidoreductases / metabolism*


  • Anthracyclines
  • Free Radicals
  • Doxorubicin
  • Iron
  • Oxidoreductases