Bixa orellana L. (Bixaceae) and Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) Essential Oils Formulated in Nanocochleates against Leishmania amazonensis.

Leishmaniasis is a group of neglected tropical diseases caused by protozoan parasites of the Leishmania genus. The absence of effective vaccines and the limitations of current treatments make the search for effective therapies a real need. Different plant-derived essential oils (EOs) have shown antileishmanial effects, in particular from Bixa orellana L. (EO-Bo) and Dysphania ambrosioides (L.) Mosyakin & Clemants (EO-Da). In the present study, the EO-Bo and EO-Da, formulated in nanocochleates (EO-Bo-NC and EO-Da-NC, respectively), were evaluated in vitro and in vivo against L. amazonensis. The EO-Bo-NC and EO-Da-NC did not increase the in vitro inhibitory activity of the EOs, although the EO-Bo-NC showed reduced cytotoxic effects. In the animal model, both formulations (30 mg/kg/intralesional route/every 4 days/4 times) showed no deaths or weight loss greater than 10%. In the animal (mouse) model, EO-Bo-NC contributed to the control of infection (p < 0.05) in comparison with EO-Bo treatment, while the mice treated with EO-Da-NC exhibited larger lesions (p < 0.05) compared to those treated with EO-Da. The enhanced in vivo activity observed for EO-Bo-NC suggests that lipid-based nanoformulations like nanocochleates should be explored for their potential in the proper delivery of drugs, and in particular, the delivery of hydrophobic materials for effective cutaneous leishmaniasis treatment.