Leishmanicide activity of oleanolic acid against promastigotes of Leishmania braziliensis and Leishmania chagasi
Leishmaniasis is a major worldwide health problem, with around 12 million people infected and 600 thousand new cases appearing each year. In Brazil, 30 thousand new cases appear annually only in the Northeast region. Pentavalent antimonals are the first line treatment for leishmaniasis. Disadvantages such as costs, long-term treatment, side effects and low efficacy against many strains have been reported. Although great efforts had done along the last century to develop new drugs for leishmaniasis treatment, a drug with high efficacy and low side effects is still need. Among all strategies used to develop new agents against leishmaniasis, the research of natural products produced good results. This work investigated the leishmanicidal activity of oleanolic acid (OA), a natural triterpene found in a great variety of plants against promastigotes forms of L. braziliensis and L. chagasi. Promastigotes were incubated in the presence of different concentrations of OA, which was added only once to the cultures. After 3 days at 26°C, parasite survival was estimated by counting viable or motile forms. OA exhibited a good anti-promastigote activity both for L. braziliensis and L. chagasi, reducing parasite survival in 75 and 94%, respectively, when we used 50µg/ml of the drug. DMSO 1% was used as solvent control. These results suggest that L. braziliensis is less susceptive than L. chagasi. No toxicity to the macrophages was observed after the treatment with OA, as measured by their spreading and adherence to glass surface. These results reinforce that OA could be a strong candidate for an antileishmanial drug.
Acknowledgements: Hebron Farmacêutica, MackPesquisa, PIBIC/Mackenzie, CNPq, FAPERJ