Leishmanicidal Activity of Betulin Derivatives in Leishmania amazonensis; Effect on Plasma and Mitochondrial Membrane Potential, and Macrophage Nitric Oxide and Superoxide Production

Abstract

Herein, we evaluated in vitro the anti-leishmanial activity of betulin derivatives in Venezuelan isolates of Leishmania amazonensis, isolated from patients with therapeutic failure. Methods: We analyzed promastigote in vitro susceptibility as well as the cytotoxicity and selectivity of the evaluated compounds. Additionally, the activity of selected compounds was determined in intracellular amastigotes. Finally, to gain hints on their potential mechanism of action, the effect of the most promising compounds on plasma and mitochondrial membrane potential, and nitric oxide and superoxide production by infected macrophages was determined. Results: From the tested 28 compounds, those numbered 18 and 22 were chosen for additional studies. Both 18 and 22 were active (GI50 ≤ 2 µM, cytotoxic CC50 > 45 µM, SI > 20) for the reference strain LTB0016 and for patient isolates. The results suggest that 18 significantly depolarized the plasma membrane potential (p < 0.05) and the mitochondrial membrane potential (p < 0.05) when compared to untreated cells. Although neither 18 nor 22 induced nitric oxide production in infected macrophages, 18 induced superoxide production in infected macrophages. Conclusion: Our results suggest that due to their efficacy and selectivity against intracellular parasites and the potential mechanisms underlying their leishmanicidal effect, the compounds 18 and 22 could be used as tools for designing new chemotherapies against leishmaniasis.

Antileishmanial and Antitrypanosomes Drugs for the Current Century

“…Two molecules showed high potency and selectivity against the intramacrophage stage of L. amazonensis . These properties, together with the induction of superoxide production by macrophages by one of the synthesized compounds, support the further exploration of this series to develop new chemotherapeutic agents against leishmaniasis [ 37 ]. Ideally, the identification of the therapeutic target and MoA of currently used or new drugs would provide a rational background for further improving treatments and preventing the emergence of resistance.…”

Otimização de neolignanas como protótipos farmacêuticos para a leishmaniose visceral: mecanismo de ação e estudos farmacocinéticos

“…Dessa forma, é possível sugerir que tais alterações são resultantes da entrada do composto no parasita, que pode estar gerando alterações no fluxo íons através da ligação a proteínas de transporte específicas como H + -ATPases. Estudos da literatura também reportaram a ação de produtos naturais, incluindo neolignanas, no potencial da membrana plasmática de parasitas de Leishmania (Das et al, 2017;Alcazar et al 2021).…”