Effects of trypanocidal drugs on protein biosynthesis in vitro and in vivo by Trypanosoma cruzi.

Nifurtimox (NF) and benznidazole (BZ), drugs used in the treatment of Chagas' disease, did not inhibit protein biosynthesis in in vitro homologous cell-free systems isolated from Trypanosoma cruzi and Crithidia fasciculata; nevertheless, their addition to growing cultures caused polyribosomal depolymerization. On the other hand, Berenil, Antrycide and suramin, used against African trypanosomiasis, inhibited protein biosynthesis in vitro but did not affect ribosomal distribution, probably due to low permeability to the drugs. The results suggest that the inhibition by NF and BZ of protein synthesis, measured as [14C]leucine incorporation by other authors, is indirect, probably through inhibition of nucleic acid synthesis and energy metabolism.