Anti-leishmanial activities of selenium nanoparticles and selenium dioxide on Leishmania infantum

Leishmania infantum is one of the important causes of visceral leishmaniasis in many countries. There are different complications for treatment of leishmaniasis such as toxicity and drug resistant. So far, there isn’t any information about the effects of selenium nanoparticles and selenium dioxide (chemical form of selenium) on Leishmania parasites; hence, the aim of the present study is to investigate in vitro effects of six dilutions of these drugs on L. infantum. Anti-leishmanial activities were studied by adding different dilutions of 2.5, 5, 10, 25, 50, and 100 μg/ml of the drugs into promastigote cultures. Promastigote cytotoxicity was tested using the colorimetric MTT assay. Anti-amastigote activity was assessed in peritoneal macrophages of BALB/c mice. Also, cytotoxic effect of these drugs was evaluated on uninfected macrophages. The results showed that both of drugs have dose-dependent anti-leishmanial activities. Selenium NPs have more growth-inhibitory effect on promastigotes than SeO₂; while the IC50 (50 % inhibitory concentration) was determined to be 25 and 50 μg/ml, respectively. The mean numbers of amastigotes per macrophage in selenium NPs-treated groups were less than SeO₂-treated and control groups. The IC50 of selenium NPs was 10 μg/ml and SeO₂ was 25 μg/ml for amastigotes. Also, the IC50 of selenium NPs and SeO₂ for uninfected macrophages were calculated to be 100 and 50 μg/ml, respectively. In addition, selenium NPs has less cytotoxic effect than SeO₂ on uninfected macrophages. These findings suggest that selenium NPs have more anti-leishmanial properties and less cytotoxic effects than SeO₂ against L. infantum.