Effects of isoxazolyl-naphthoquinoneimines on growth and oxygen radical production inTrypanosoma cruzi andCrithidia fasciculata

Several 4-(aminomethylisoxazolyl)-1,2-naphthoquinones inhibited growth and DNA synthesis inTrypanosoma cruzi and stimulated O₂ uptake and generation by the parasite epimastigotes and their mitochondrial and microsomal membranes; these results support the idea that oxygen radicals play a role in quinone toxicity. Maximal effects on respiration and generation were observed with antimycin-inhibited cells. Similar results as well as stimulation of H₂O₂ production were obtained withCrithidia fasciculata despite the presence of catalase in this organism.Acknowledgments. This work was aided by grants from the University of Buenos Aires, the Scientific Office of the American States Organization and CEDIQUIFA (Buenos Aires). S.G.G. and M.P.M.P. are Research Fellows and A.O.M.S. is Career Investigator of CONICET (Argentina). L. T. Viñas and M. G. Gutierrez lent able technical assistance.