Effects of hydroquinones on intact Trypanosoma cruzi epimastigotes.
1. Hydroquinones inhibited the culture growth of Trypanosoma cruzi epimastigotes at concentrations lower than 1 mM. 2. Hydroquinones inhibited the oxygen consumption on the intact Trypanosoma cruzi cells. I50 values for hydroquinone, terbutylhydroquinone and 2,5-di-t-butylhydroquinone were 24.87 mM, 0.88 mM and 0.26 mM, respectively. t-Butylhydroquinone and 2,5-di-t-butylhydroquinone had a Michaelian type kinetic inhibition; hydroquinone also showed a Michaelian type kinetic inhibition at low concentrations but at higher concentrations it showed a positive cooperativity. 3. These hydroquinones changed the NAD(P) redox-state to a more reduced state and that of cytochrome b to a more oxidized state. The magnitude of the redox-state change was dependent of the hydrophobicity of the derivates. 4. These results suggest that the growth and oxygen uptake inhibition by the hydroquinones is due to a blockage of the mitochondrial electron transport chain before cytochrome b.
Aldunate
J
J
Department of Biochemistry, Faculty of Medicine, University of Chile, Santiago.
Traipe
L
L
Spencer
P
P
Morello
A
A
Repetto
Y
Y
D000818:Animals; D003573:Cytochrome b Group / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004579:Electron Transport / Q000187:drug effects; D006873:Hydroquinones / Q000494:pharmacology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects*; D013056:Spectrophotometry, Ultraviolet; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D003573:Cytochrome b Group; D006873:Hydroquinones; D009243:NAD; C019359:2,5-di-tert-butylhydroquinone; D009249:NADP; C018855:2-tert-butylhydroquinone; C031927:hydroquinone