The antiproliferative effect of
julocrotine, an
alkaloid isolated from Croton pullei var. glabrior (Euphorbiaceae), was studied in the macrophage amastigote and promastigote stages of the protozoan Leishmania (L.) amazonensis, which causes
cutaneous leishmaniasis in the New World.
Julocrotine showed a dose-dependent effect against the amastigote and promastigote forms, where 79 μM
julocrotine inhibited promastigote growth by 54%, with an IC50 of 67 μM. To analyze the antiamastigote activity of the
drug, murine peritoneal macrophages infected with L. amazonensis promastigotes were treated with different concentrations of
julocrotine. An 80% inhibition of amastigote development was observed using 79 μM
julocrotine for 72 h, with an IC50 of 19.8 μM. In addition, ultrastructural observation of the parasites showed a significant reduction in the number of amastigotes in the parasitophorous vacuoles and morphological changes in promastigotes, such as swelling of the mitochondrion,
chromatin condensation, presence of membranous structures near the Golgi complex, and some vesicle bodies in the flagellar pocket. A colorimetric assay (MTT), which measures cytotoxic metabolic activity, showed that macrophages maintain their viability
after treatment with the
drug. These results suggest that
julocrotine effectively inhibits the growth of parasites and does not have any cytototoxic effects on the host cell.