Tetraoxane antimalarials and their reaction with Fe(II)
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Smith, Kirsten S.
Yang, Young S.
Diaz, Damaris S.
Smith, Philip L.
Milhous, Wilbur K.
Article (Published version)
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Mixed tetraoxanes 5a and 13 synthesized from cholic acid and 4-oxocyclohexanecarboxylic acid were as active as artemisinin against chloroquine-susceptible, chloroquine-resistant, and multidrug-resistant Plasmodium falciparum strains (IC50, IC90). Most active 13 is metabolically stable in in vitro metabolism studies. In vivo studies on tetraoxanes with a C(4'') methyl group afforded compound 15, which cured 4/5 mice at 600 and 200 mg, kg(-1), day(-1), and 2/5 mice at 50 mg, kg(-1), day(-1), showing no toxic effects. Tetraoxane 19 was an extremely active antiproliferative with LC50 of 17 nM and maximum tolerated dose of 400 mg/kg. In Fe(II)-induced scission of tetraoxane antimalarials only RO center dot radicals were detected by EPR experiments. This finding and the indication of Fe(IV)=O species led us to propose that RO center dot radicals are probably capable of inducing the parasite's death. Our results suggest that C radicals are possibly not the only lethal species derived from per...oxide prodrug antimalarials, as currently believed.
Source:Journal of Medicinal Chemistry, 2006, 49, 13, 3790-3799
- Amer Chemical Soc, Washington