Antileishmanial activity of the essential oil from Bixa orellana.

Leishmaniasis is a neglected tropical disease caused by Leishmania protozoa. There is currently no vaccine against leishmaniasis, and chemotherapy remains the only effective control. However, conventional drugs are toxic, expensive, and require long periods of treatment, and resistance to clinical chemotherapeutic agents is emerging. Recent research on plants has shown a successful approach to obtain new antileishmanial alternatives. Herein, the in vitro and in vivo effects of the essential oil from Bixa orellana seeds against Leishmania amazonensis were evaluated. A total of 73 compounds were detected by gas chromatography-mass spectrometry analysis, of which ishwarane (18.6%) and geranylgeraniol (9.1%) were the major components. The oil showed activity against intracellular amastigote form (IC50  = 8.5 µg/mL), while the cytotoxic concentration was sevenfold higher for the host cells. The ability of Bixa oil to control disease progression of established cutaneous leishmaniasis in BALB/c mice was demonstrated, after a treatment with 30 mg/kg by intraperitoneal administration over 14 days. The present study reports for the first time the antileishmanial potentialities of the essential oil from B. orellana.