Plasmodium falciparum: Selenium-induced cytotoxicity to P. falciparum

The in vitro antimalarial activity of sodium selenite (NaSe) was investigated and the mechanism of its action was studied. NaSe had antimalarial activity against both the chloroquine-susceptible strain FCR-3 and chloroquine-resistant strain K-1 of Plasmodium falciparum. The shrunken cytoplasm of the parasite was observed in a smear 12h after treatment with NaSe. Co-treatment with copper sulfate (CuSO₄) in culture did not affect the antimalarial activity of NaSe, but NaSe cytotoxicity against the mammalian cell line Alexander was decreased significantly. The intracellular reduced glutathione level of parasitized red blood cells was decreased significantly by treatment with NaSe, and the decrease was consistent with their mortality. Treatment with NaSe had a strong inhibitory effect on plasmodial development, and NaSe cytotoxicity to human cells was decreased by co-treatment with CuSO₄. These results suggest that co-treatment with NaSe and CuSO₄ may be useful as a new antimalarial therapy. Index Descriptors and Abbreviations: Plasmodium falciparum; antiplasmodial activity; sodium selenite; pRBCs, parasitized red blood cells; RBCs, red blood cells; GSH, reduced glutathione; NaSe, sodium selenite; CuSO₄, copper sulfate