In vitro leishmanicidal activity of monoterpenes present in two species of Protium (Burseraceae) on Leishmania amazonensis.

ETHNOPHARMACOLOGICAL RELEVANCE: Leishmaniasis is a neglected disease that affects millions of people around the world. Parasite resistance and the toxicity to the current treatments lead to the search for new effective molecules. Plants are widely used in traditional and indigenous medicine to treat different diseases. The oleoresin of the genus Protium, which is rich in volatile compounds active against different microorganisms, is among these plants. AIM: The aim of this study was to evaluate the leishmanicidal potential of Protium altsonii (PaEO) and P. hebetatum (PhEO) (Burseraceae) oleoresins, as well as of three representative monoterpenes in their constitution: α-pinene, p-cymene and 1,8-cineole. MATERIALS AND METHODS: Protium altsonii (PaEO) and P. hebetatum (PhEO) oleoresins and three of their constituents were tested in vitro on promastigotes and amastigotes-infected macrophages in different concentrations. Their toxicity for macrophages was analyzed by XTT assay and phagocytic ability. It was evaluated the ability of the compounds to induce NO production on treated-macrophages using Griess reaction and the effect of them in lipid profile on treated-parasite through Thin Layer Chromatography. RESULTS: Our data showed that both essential oils have toxic effect on promastigotes and amastigotes of L. amazonensis in vitro in a dose-dependent manner. PaEO IC50 were 14.8 µg/mL and 7.8 µg/mL and PhEO IC50s were 0.46 µg/mL and 30.5 µg/m for promastigotes and amastigotes, respectively. Toxicity to macrophages was not observed at 50 µg/mL with both EOs. The compounds 1,8- cineole, α-pinene, and p-cymene inhibited amastigotes survival in a dose-dependent manner with IC50s of 48.4 µg/mL, 37 µg/mL, 46 µg/mL, respectively. Macrophage viability was around 90% even at 200 µg/mL and the phagocytic capacity was not altered in the treated-macrophages to up 50 µg/mL. The compounds were not able to modulate the nitric oxide production either at rest or LPS-activated macrophages. In addition, treated promastigote revealed an important change in their lipid profile after 48 h at 50 µg/mL in the presence of the compounds. CONCLUSIONS: The results indicate that oleoresins of Protium genus are potent against Leishmania and α-pinene, p-cymene and 1,8-cineole have anti-Leishmania properties that could be explored in synergistic assays in order to develop new drug candidates.

The in vitro antileishmanial activity of essential oil from Aloysia gratissima and guaiol, its major sesquiterpene against Leishmania amazonensis.

Leishmaniases is a tropical disease caused by protozoa of the genus Leishmania for which the current treatment is expensive, besides increasing reports of parasite resistance. This study investigated the anti-Leishmania amazonensis activity of the essential oil from Aloysia gratissima (AgEO) and guaiol, the major sesquiterpene constituent in the oil. Our results showed that AgEO killed promastigotes and intracellular amastigotes at an IC50 of 25 and 0·16 µg mL-1, respectively, while guaiol killed amastigotes at an IC50 of 0·01 µg mL-1. Both AgEO and guaiol were safe for macrophages up to 100 µg mL-1, as evaluated by the dehydrogenase activity, membrane integrity and phagocytic capacity. AgEO and guaiol did not induce nitrite oxide (NO) in resting macrophages and inhibited the production of NO in lipopolysaccharide-stimulated macrophages. The ultrastructural analysis suggested that AgEO and guaiol act directly on parasites, affecting promastigotes kinetoplast, mitochondrial matrix and plasma membrane. Together, these results pointed out that AgEO and guaiol could be promising candidates to develop anti-Leishmania drugs.