Leishmaniasis is a tropical disease caused by parasite Leishmania. Twelve million people are currently infected with Leishmania and up to 350 million people are at risk of infection [1]. Drugs available for the treatment of this infection have many limitations including resistance and toxicities [2]. It is known that plants represent an important source of potential biological agents. In a previous work, we described the antileishmanial activity of eupomatenoid-5, an isolated compound of Piper regnellii var. pallescens [3]. The aim of this work was to investigate the mechanism of action induced by this compound in the cell death of L. amazonensis. For this, promastigotes were treated with 30, 85 or 170µM eupomatenoid-5 and incubated with Rh123 or annexin-V FITC/PI. Eupomatenoid-5 caused a decrease in Rh123 fluorescence of 76.8% for 30µM and 95.9% for 85µM indicating mitochondrial depolarization. Moreover, at higher concentrations (85.0 and 170.0µM), annexin-V fluorescence intensity was increased by more than 30%, indicating phosphatidylserine exposure, an apoptotic marker that is present in the outer leaflet of plasmalemma. Treatment of promastigotes also resulted in 16% and 28% increase in the proportion of cells in sub-G0/G1 phase at 30 and 85µM, respectively, showing that eupomatenoid-5 induced G0/G1 phase cell cycle arrest, corresponding to DNA fragmentation. It is possible to suppose that the antileishmanial action of eupomatenoid-5 may involve its effect on the mitochondrial function leading to parasite death by apoptosis.
References:
[1] WHO. Leishmaniasis: The Global Trend. http://www.who.int/neglected_diseases/integrated_media leishmaniasis/en/index.html (2012).
[2] M. Banerjee et al. European Journal of Medicinal Chemistry 55 (2012) 449 – 454.
[3] M.C. Vendrametto et al. Parasitology International 59 (2010) 154 – 158.
Acknowledgements:
CNPq, Fundação Araucária, FINEP, and CAPES.
