Abstract
Six dietary isothiocyanates, allyl-isothiocyanate, benzyl-isothiocyanate,
phenylethyl-isothiocyanate, sulforaphane, erucin, and iberin, were tested
for their trypanocidal activities in vitro using culture-adapted
bloodstream forms of Trypanosoma brucei. All isothiocyanates showed a
dose-dependent effect on the growth of trypanosomes. Five compounds
displayed MIC values of 10 µM and GI50 values of around 1.5 µM,
while allyl-isothiocyanate exhibited values of 100 and 11 µM, respectively.
The compounds showed similar cytotoxic activities against human HL-60 cells
with GI50 values of 1–4 µM and MIC values of 10–100 µM.
Short-term experiments revealed that, with the exception of
allyl-isothiocyanate, isothiocyanates at a concentration of 10 µM kill
trypanosomes within 1–4 h of incubation. In contrast, HL-60 cells were not
affected by any of the compounds in short-term incubation experiments.
Sulforaphane, the most intensively studied isothiocyanate, was also
investigated for its in vivo trypanocidal activity. However,
administration of 50 mg/kg sulforaphane orally or intraperitoneally for four
days had no effect on the parasitaemia in mice infected with T.
brucei compared to control animals treated with vehicle alone.
Key words
Trypanosoma brucei
- sleeping sickness - isothiocyanates - sulforaphane
