Inhibition of growth and of thymidine incorporation into DNA in Tetrahymena by chlorpromazine, pimozide and penfluridol

Effect of calmodulin inhibitors on viability and mitochondrial potential of Plasmodium falciparum in culture

Calmodulin inhibitors are toxic for a variety of protozoa. Chlorpromazine, calmidazolium, and trifluoperazine inhibited the incorporation of [3H]hypoxanthine and [3H]phenylalanine into Plasmodium falciparum organisms in cultures with 50% inhibitory concentrations varying from 5.1 microM (with calmidazolium) to 48 microM (with chlorpromazine), the former being more sensitive than the latter. However, these concentrations also immediately dissipated rhodamine 123 from the parasite mitochondrion. Similar concentrations inhibit other protozoa, as well as mammalian cells, and the possibility that mitochondrial function rather than that of calmodulin is the target of these drugs should be considered.

Trypanosoma cruzi: possible control of parasite transmission by blood transfusion using amphiphilic cationic drugs

About 200 clinically used amphiphilic cationic drugs have been shown to be active in vitro against Trypanosoma cruzi at concentrations of less than or equal to 1 mM. Activity against epimastigote and trypomastigote forms was similar, and in both cases the most potent drugs were litracene, maprotiline, thioproperazine, and the acridines: acranil, aminacrine, and mepacrine. Fluorescence microscopy demonstrated that epimastigotes rapidly accumulate acridines initially in discrete subcellular organelles. The amount of drug incorporated during 15 min of incubation was sufficient to produce subsequent lysis of both trypomastigotes and epimastigotes within 24 hr at 4 C. Trypanocidal activity was dependent on the extracellular pH (optimum greater than or equal to 8) and drug exposure time, but was independent of red blood cell density, serum dilution, and temperature (4 to 37 C). Despite their trypanocidal activity, amphiphilic cationic drugs appear to have no significant effect on the energy state of red blood cells at a concentration of 1 mM. These drugs have a possible role in the prevention of Chagas' disease by blood transfusion.