Antileishmanial effect of fruit seeds from Platonia insignis against macrophage-internalized amastigote forms of Leishmania amazonensis

Resumen

Introduction: Leishmaniasis is an infectious parasitic disease with clinical manifestations which compromise skin tissue, mucosas and viscera. Previous studies have found that the fruit seeds of Platonia insignis Mart. (Clusiaceae) have a marked effect against promastigote forms of Leishmania amazonensis.
Objective: Evaluate the antileishmanial activity of an extract obtained from Platonia insignis fruit seeds (known as BBI) against L. amazonensis amastigotes inside macrophages.
Methods: Upon BBI incubation (0.78 to 50 mg/ml), estimation was made of the number of infected macrophages and parasites. Evaluation was performed of BBI cytotoxicity by the MTT assay (12.5 to 400 µg/ml) in non-infected murine macrophages, and of hemolytic activity in human O⁺ erythrocytes. Phagocytic capacity, lysosomal volume and nitrite concentration were also evaluated to determine the participation of immunomodulatory mechanisms.
Results: BBI reduces infection in macrophages (CI₅₀=3.95 mg/ml). Treatment of murine peritoneal macrophages increases nitrite production, phagocytic capacity and lysosomal volume, confirming the involvement of immunomodulation in the activity of BBI against leishmaniasis. BBI displayed low toxicity for murine macrophages at a mean cytotoxic concentration (CC₅₀) of 73.26 mg/ml, and hemolytic activity below 5.0% at the highest concentration assayed (400 µg/ml).
Conclusions: P. insignis fruit seed extract is a promising alternative to treat leishmaniasis, as well as to manufacture drugs with a potential application in the treatment of this disease.

Key words: leishmaniasis; nitrite; plant oils; protozoan infections; phagocytosis.