Medicinal plants from the Brazilian Amazonian region and their antileishmanial activity:a review

Leishmaniasis, a neglected disease caused by Leishmania protozoans, primarily affects people in tropical and subtropical areas. Chemotherapy based on the use of pentavalent antimonials, amphotericin B, paromomycin, miltefosine and liposomal amphotericin B is currently the only effective treatment. However, adverse effects, long-term treatment and the emergence of parasite resistance have led to the search for alternative treatments. Natural products used in traditional medicine provide an unlimited source of molecules for the identification of new drugs, and the Amazon region has abundant biodiversity that includes several species of plants and animals, providing a rich source of new products and com- pounds. Although the literature describes numerous promising compounds and extracts for combating Leishmania protozoans, the results of such research have not been embraced by the pharmaceutical industry for the development of new drugs. Therefore, this review focused on the antileishmanial activity of extracts, isolated compounds and essential oils commonly used by the local population in the Brazilian Amazonian region to treat several illnesses and described in the literature as promising compounds for combating leishmaniasis.

In vitro antileishmanial effects of Physalis angulata root extract on Leishmania infantum

Objective： In the present study, we evaluated the effects of the aqueous extract of Physalis angulata root （AEPa） on Leishmania infanturn proliferation, morphology, and the driving mechanism in leishmanicidal activity and modulatory action on macrophages. Methods： I., infantum promastigotes were treated with 50 and 100 μg/mL AEPa for 72 h and then antipro- mastigote assay was performed by counts in a Newbauer chamber, morphological changes were analyzed by transmission electron microscopy and the mechanism of the leishmanicidal activity was detected. In addition, macrophages were infected with L. infantum and were used to evaluate anti-amastigote activity of AEPa and effects of AEPa on cytokine secretion after 72-hour treatment. Results： Treatment with AEPa reduced the numbers ofL infantum promastigotes （50% inhibitory concen- tration （ICso） = 65.9μg/mL; selectivity index （SI）= 22.1） and amastigotes （ICso = 37.9 μg/mL; SI = 38.5） compared with the untreated control. Amphotericin B reduced 100% of the promastigote numbers after 72 h of treatment （IC50 = 0.2μg/mL）. AEPa induced several morphological changes and increased the production of reactive oxygen species and apoptotic death in promastigotes after treating for 72 h. AEPa （100 μg/mL） promoted tumor necrosis factor-α secretion in macrophages infected with L. infantum after 72 h of treatment, but did not induce an increase in this cytokine in noninfected macrophages. In addition, AEPa showed no cytotoxic effect on J774-A1 cells （50% cytotoxic concentration 〉1000μg/mL）. Conclusion： AEPa presented antileishmanial activity against the promastigotes and amastigotes of I.. infantum without macrophage cytotoxicity; these results show that natural products such as P. angulata have leishmanicidal potential and in the future may be an alternative treatment for leishmaniasis.