Leishmanicidal and apoptotic activities of oleuropein on Leishmania major.

Background: Leishmania is a unicellular protozoan parasite causing a wide range of human diseases ranging from localized self-healing cutaneous lesions to fatal visceral infections.

Objective: The aim of the present study is to assess the cytotoxic, anti-proliferative, and apoptotic effects of oleuropein on Leishmania major promastigotes (MHOM/SA/84/JISH) and to compare its effects with the reference drug sodium stibogluconate (pentostam).

Methods: Cytotoxicity and promastigote proliferation were measured using MTT colorimetric assay. Furthermore, the Annexin V/propidium iodide staining technique followed by flow cytometry was used for studying the cell death properties of oleuropein.

Results: In the present report we have shown that oleuropein, a pharmacologically safe, natural product of olive leaf, has a potent leishmanicidal effect. Indeed, oleuropein exhibits cytotoxic and anti-proliferative effects against Leishmania major promastigotes. Moreover, oleuropein triggers death through apoptosis, whereas pentostam induces death mainly via necrosis on Leishmania major promastigotes.

Conclusion: Here we demonstrate for the first time that the non-toxic, natural product oleuropein has apoptotic properties against Leishmania major promastigotes. Further studies are needed to investigate its molecular pathway.