Hepatocellular bioactivation and cytotoxicity of the synthetic endoperoxide antimalarial arteflene

Chem Biol Interact. 2004 Mar 15;147(2):173-84. doi: 10.1016/j.cbi.2003.12.005.

Abstract

Arteflene is a synthetic endoperoxide antimalarial. Its peroxide bridge undergoes iron(II)-mediated reduction in vitro which yields a carbon-centered cyclohexyl radical and a mixture of cis- and trans-alpha,beta-unsaturated ketones (enones). The enones are biliary metabolites in rats and therefore surrogate markers of bioactivation. Arteflene is reported to be more cytotoxic to primary rat hepatocytes than some non-endoperoxide antimalarials. Hepatic metabolism of arteflene was investigated in recirculating isolated perfused rat livers, and the drug's metabolism and cytotoxicity were compared using hepatocytes from male rats. Both preparations metabolized [(14)C]arteflene to cis- and trans-[(14)C]enone, 8-hydroxyarteflene glucuronide and an unassigned isomeric glucuronide. During a 2 h liver perfusion, the cis- and trans-enones recovered in bile represented 8.1 +/- 3.4 and 11.3 +/- 4.6% (mean +/- S.D., N=6), respectively, of the [(14)C]arteflene (52 microM) added to the perfusate. After a 3 h incubation of [(14)C]arteflene (10 microM) with hepatocytes in suspension, the cis- and trans-enones comprised, respectively, 14.8 +/- 7.1 and 2.1 +/- 1.0% (N = 4) of the recovered radioactivity; the corresponding data for cultured hepatocytes being 18.6 +/- 6.9 and 3.3 +/- 2.2%. Arteflene was significantly (P < 0.05) toxic to isolated hepatocytes with reference to extramitochondrial reductase activity (tetrazolium reduction) but not enzyme leakage when the cells were exposed to drug concentrations > or =50 microM for 24 h. Cellular glutathione was depleted under these conditions. Therefore arteflene was acutely cytotoxic, though only at relatively high concentrations, when it was metabolized via a pathway which generates carbon-centered radicals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimalarials / metabolism*
  • Antimalarials / toxicity
  • Artemisinins / metabolism*
  • Artemisinins / toxicity
  • Bile / chemistry
  • Bile / metabolism
  • Bridged Bicyclo Compounds, Heterocyclic / metabolism*
  • Bridged Bicyclo Compounds, Heterocyclic / toxicity
  • Carbon Radioisotopes
  • Chromatography, High Pressure Liquid
  • Dose-Response Relationship, Drug
  • Glutathione / analysis
  • Glutathione / metabolism
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Hepatocytes / pathology
  • In Vitro Techniques
  • Liver / drug effects
  • Liver / metabolism*
  • Liver / pathology
  • Male
  • Perfusion
  • Rats
  • Rats, Wistar
  • Styrenes / metabolism*
  • Styrenes / toxicity

Substances

  • Antimalarials
  • Artemisinins
  • Bridged Bicyclo Compounds, Heterocyclic
  • Carbon Radioisotopes
  • Styrenes
  • arteflene
  • Glutathione