Anti-trypanosome effects of nutritional supplements and vitamin D3: in vitro and in vivo efficacy against Trypanosoma brucei brucei.

Background: Previous publications suggest that nutritional supplements have anti-trypanosome activity in vitro, although apparent efficacy was not noted in vivo. This study was conducted by experimentally infecting mice with Trypanosoma brucei brucei to assess the anti-trypanosome activity of various nutritional supplements with the hope of finding possible application in the treatment of African trypanosomiasis.

Methods: Activities of nutritional supplements were screened in vitro against bloodstream forms of T. b. brucei. To evaluate selectivity, we used two mammalian cells, Jurkat cells and Vero cells. The IC50 values and selectivity index values were calculated, and supplements with promising efficacy in vitro were selected for further testing in vivo. Mice were infected intraperitoneally with 1 × 10(3) T. b. brucei. We observed parameters for disease progression such as parasitemia, red blood cell count, white blood cell count, survivability, and splenomegaly. Morphological profiles after the treatment were analyzed by scanning electron microscopy.

Results: Vitamin D3 showed anti-trypanosome efficacies both in vitro and in vivo. It seemed to have suppressive effects on parasitemia, and spleen weight was also significantly lower in vitamin D3-treated mice when compared to non-treated control mice. There was, however, no significant prolonged survivability of infected mice treated with vitamin D3. Among green tea extracts, polyphenon-60 and epigallocatechin gallate had suppressive effects against T. b. brucei in vitro, but in vivo efficacies were marginal.

Conclusions: Treatment with nutritional supplements, vitamin D3, and polyphenon-60 seemed to have anti-trypanosome activity in vitro and protective activity to some extent in vivo, respectively, although those supplements themselves did not have curable effects. The exact mechanisms of action are not clear, but the significant efficacy in vitro suggested direct effects of supplements against African trypanosome parasites.