In vitro leishmanicidal activity of Hancornia speciosa latex against Leishmania (Leishmania) amazonensis

Background

Leishmaniasis is a neglected tropical disease whose available treatment has limitations. Hancornia speciosa Gomes, a tree native to Brazil, has been studied for its medicinal properties, including antimicrobial and healing properties. However, its effect on parasites of the Leishmania genus still needs to be elucidated.

Purpose

To evaluate the leishmanicidal activity for potential therapeutic use of H. speciosa latex and its fractions on Leishmania (Leishmania) amazonensis promastigotes and amastigotes, as well as to analyze its cytotoxic effects on RAW264.7 cells and murine peritoneal macrophages.

Methods

The anti-promastigote activity of latex and its fractions was evaluated by cell viability assays via MTT in L. (L.) amazonensis and monitoring the parasite's growth kinetics by counting under light microscopy. To evaluate anti-amastigote activity, RAW264.7 cells and murine peritoneal macrophages infected with amastigotes were analyzed using microscopy, immunofluorescence, and flow cytometry assays. The cytotoxicity of latex and its fractions was evaluated in these cells via MTT assay.

Results

The H. speciosa latex and its fractions showed anti-promastigote activities in L. (L.) amazonensis, reducing its proliferation and viability and altering its morphology. These did not interfere with the viability of RAW264.7 cells and peritoneal macrophages. Crude latex and F < 10 kDa at 5 % reduced the infection of intracellular amastigotes in peritoneal macrophages to 32 % and 18 % after 24 h of treatment, respectively. Under the same conditions, the F > 10 kDa fraction showed 82 % of infected cells. The evaluation of the latex composition showed that the F > 10 kDa fraction has the highest concentration of carbohydrates, followed by phenolic compounds and proteins. In contrast, the F < 10k Da fraction presented fewer phenolic compounds and carbohydrates.

Conclusions

These results indicate that H. speciosa crude latex and F < 10 kDa have intense leishmanicidal activity against L. (L.) amazonensis promastigotes and amastigotes internalized by macrophages. Additionally, the lack of cytotoxicity indicates that H. speciosa latex is a strong candidate for new alternative treatments for leishmaniasis.