AUTHOR=Inacio Job D. F. , Fonseca Myslene S. , Limaverde-Sousa Gabriel , Tomas Ana M. , Castro Helena , Almeida-Amaral Elmo E. 

TITLE=Epigallocathechin-O-3-Gallate Inhibits Trypanothione Reductase of Leishmania infantum, Causing Alterations in Redox Balance and Leading to Parasite Death

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.640561

DOI=10.3389/fcimb.2021.640561

ISSN=2235-2988

ABSTRACT=<p><italic>Leishmania infantum</italic> is a protozoan parasite that causes a vector borne infectious disease in humans known as visceral leishmaniasis (VL). This pathology, also caused by <italic>L. donovani</italic>, presently impacts the health of 500,000 people worldwide, and is treated with outdated anti-parasitic drugs that suffer from poor treatment regimens, severe side effects, high cost and/or emergence of resistant parasites. In previous works we have disclosed the anti-<italic>Leishmania</italic> activity of (-)-Epigallocatechin 3-<italic>O</italic>-gallate (EGCG), a flavonoid compound present in green tea leaves. To date, the mechanism of action of EGCG against <italic>Leishmania</italic> remains unknown. This work aims to shed new light into the leishmanicidal mode of action of EGCG. Towards this goal, we first confirmed that EGCG inhibits <italic>L. infantum</italic> promastigote proliferation in a concentration-dependent manner. Second, we established that the leishmanicidal effect of EGCG was associated with i) mitochondria depolarization and ii) decreased concentration of intracellular ATP, and iii) increased concentration of intracellular H<sub>2</sub>O<sub>2</sub>. Third, we found that the leishmanicidal effect and the elevated H<sub>2</sub>O<sub>2</sub> levels induced by of EGCG can be abolished by PEG-catalase, strongly suggesting that this flavonoid kills <italic>L. infantum</italic> promastigotes by disturbing their intracellular redox balance. Finally, we gathered <italic>in silico</italic> and <italic>in vitro</italic> evidence that EGCG binds to trypanothione reductase (TR), a central enzyme of the redox homeostasis of <italic>Leishmania</italic>, acting as a competitive inhibitor of its trypanothione substrate.</p>