An alkaloid extract of evanta, traditionally used as anti-leishmania agent in bolivia, inhibits cellular proliferation and interferon-γ production in polyclonally activated cells

Traditional medicine and scientific studies have shown that the raw extract of Evanta [Galipea longiflora, Angostura longiflora (Krause) Kallunki] exhibits anti-leishmanial activity. We hypothesized that the healing observed when using this plant might not only be due to the direct action on the parasite, but possibly to a parallel effect on the host immune response to the parasite involved in the healing process. We show here that an alkaloid extract of Evanta (AEE) directly killed the parasite already at a dose of 10 μg/ml, but at this low concentration, AEE did not have a major effect on viability and proliferation of eukaryotic cells. The whole extract was also found to be stronger than 2-phenylquinoline, the most prominent alkaloid in AEE. AEE was not directly stimulating B or T cells or J774 macrophages. However, it interfered with the activation of both mouse and human T cells, as revealed by a reduction of in vitro cellular proliferation and interferon-gamma (IFN-γ) production. The effect was more evident when the cells were pretreated with AEE and subsequently stimulated with the polyclonal T-cell activators Concanavalin A and anti-CD3. Taken together, our results suggest that Evanta have a direct leishmanicidal effect and due to the effect on IFN-γ production it might contribute to control the chronic inflammatory reaction that characterize Leishmania infection pathology, but in vivo studies are necessary to corroborate this finding.