title: Antiproliferative synergism of the allylamine SF 86-327 and ketoconazole on epimastigotes and amastigotes of Trypanosoma (Schizotrypanum) cruzi.
abstract: We have investigated the growth-inhibitory effects of two ergosterol biosynthesis inhibitors, the dioxolane imidazole ketoconazole and the allylamine SF 86-327, alone and in combination, on the proliferative stages of Trypanosoma (Schizotrypanum) cruzi, the causative agent of Chagas' disease. Proliferation of epimastigotes in liver infusion-tryptose medium at 28 degrees C was immediately arrested by any of these drugs at greater than or equal to 3 x 10(-5) M; cell lysis occurred 24 h later. Below that concentration, SF 86-327 at concentrations down to 1 x 10(-6) M stopped growth after 48 h. In contrast, ketoconazole slowed cell growth only moderately, but proliferation finally stopped and cell lysis occurred after 120 h at 3 x 10(-6) M. Synergistic effects could be observed when the two drugs were used in combination: the concentration of SF 86-327 required to reduce the cell growth to 25% of controls in 144 h was reduced 33-fold in the presence of 1 x 10(-6) M ketoconazole, which by itself reduced growth only by 30%. Amastigotes, proliferating in Vero cells at 37 degrees C, were much more susceptible to both drugs, but ketoconazole was definitely a more potent antiparasitic agent than the allylamine in this system: whereas the concentration of SF 86-327 required to reduce the number of infected cells to 50% of controls was 1 x 10(-7) M and that required to completely eradicate the parasite was 3 x 10(-6) M, for ketoconazole these concentrations were 1 x 10(-10) M and 1 x 10(-8) M, respectively. Again, strong synergistic effects were observed when the drugs were used in combination: the concentration of SF 86-327 required to reduce the number of infected cells to 50% of controls was 100-fold lower in the presence of 10(-11) M ketoconazole, which by itself had no effects on amastigote proliferation. The parasite was completely eradicated when the drugs were used in combination at concentrations as low as 10(-9) M. Synergy of the antiproliferative effects of the drugs on both froms of the parasite was further demonstrated by concave isobolograms. On the other hand, SF 86-327 at 10(-5) M had no effects on the proliferation of Vero cells, whereas ketoconazole at 10(-7) M reduced the proliferation of these cells by 50%.
authors.affiliation: Centro de Biologia Celular, Escuela de Biologia, Facultad de Ciencias, Universidad Central de Venezuela, Caracas.
authors.forename: J A
authors.initials: JA
authors.lastname: Urbina
authors.forename: K
authors.initials: K
authors.lastname: Lazardi
authors.forename: T
authors.initials: T
authors.lastname: Aguirre
authors.forename: M M
authors.initials: MM
authors.lastname: Piras
authors.forename: R
authors.initials: R
authors.lastname: Piras
mesh_terms: D000818:Animals; D004357:Drug Synergism; D007654:Ketoconazole / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology*; D000077291:Terbinafine; D014344:Trypanocidal Agents / Q000494:pharmacology*; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000254:growth & development; D014709:Vero Cells
chemical_list: D009281:Naphthalenes; D014344:Trypanocidal Agents; D000077291:Terbinafine; D007654:Ketoconazole