Dados do Trabalho

Título

Immunomodulatory and anti-Leishmania infantum activity of Ximenia americana L. (Olacaceae) in human peripheral blood mononuclear cells

Introdução

Visceral leishmaniasis is a tropical disease that is often neglected and can be fatal to humans if not treated properly. The disease is spread through the bite of a specific insect called a sandfly, which transmits the parasite of the Leishmania genus to the host. The immune response to an infection by Leishmania infantum involves the activation of both Th1 and Th2 responses. The Th1 response helps in reducing inflammation, while the Th2 response activates the humoral immune response by producing antibodies.

Objetivo (s)

The objective of this research was to assess the leishmanicidal (parasite-killing) and immunomodulatory (immune system-modulating) properties of secondary metabolites found in the aqueous extract of Ximenia americana L. bark.

Material e Métodos

For this purpose, the immunomodulatory effects and cytotoxicity (CC50) of the secondary metabolites in the extract was analysed by measuring cytokines related to the cellular immune response. Peripheral blood mononuclear cells (PBMCs) were used for these experiments. The leishmanicidal activity against L. infantum promastigotes was assessed by determining the IC50 (concentration required to inhibit 50% of the parasites) and the Selectivity Index (SI). A phytochemical analysis using Thin Layer Chromatography (TLC) was performed to identify the compounds present in the aqueous extract and also a ultrastructure analysis of L. infantum promastigotes was performed through transmission and scanning electron microscopy to understand the changes induced by the secondary metabolites.

Resultados e Conclusão

The evaluation showed that the extract had leishmanicidal activity against L. infantum promastigotes with an IC50 of 223.2µg/mL. It did not exhibit cytotoxicity in peripheral blood mononuclear cells (PBMCs) at the tested concentrations but influenced the production of immunomodulatory cytokines. Phytochemical analysis identified hydrolysable tannins, condensed tannins, xanthines, phenolic compounds, lignins, and terpenes in the extract. Observations of changes in the ultrastructure of L. infantum promastigotes, such as disruption of the cell membrane and mitochondrial swelling, suggest that the extract acts on the cell membranes. Therefore, Ximenia americana L. could be a valuable source of antioxidant compounds. Further complementary studies are needed to investigate the effects of these secondary metabolites in vivo, considering the promising in vitro results.

Palavras-chave

Ximenia americana; Leishmania infantum; immunomodulatory; anti-Leishmania

Agradecimentos

FACEPE (IBPG-0221-2.13/20)