In silico and in vitro comparative activity of green tea components against Leishmania infantum

Green tea contains a predominant set of polyphenolic compounds with biological activities. The aim of this study was to investigate the antileishmanial activities of the main components of green tea, including catechin, (-)-epicatechin, epicatechin gallate (ECG) and (-)-epigallocatechin 3-O-gallate (EGCG), against Leishmania infantum promastigotes.

Green tea ligands and the control drug pentamidine were docked using AutoDock 4.3 software into the active sites of trypanothione synthetase and arginase, which were modelled using homology modelling programs. The colorimetric MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was used to measure L. infantum promastigotes at different concentrations of green tea compounds in a concentration- and time-dependent manner. Results were expressed as 50% and 90% inhibitory concentrations (IC₅₀ and IC₉₀, respectively).

In silico and in vitro assays showed that all of the green tea compounds have antileishmanial activity. EGCG and ECG were the most active compounds against L. infantum promastigotes, with IC₅₀ values of 27.7μM and 75μM and IC₉₀ values of 88.4μM and 188.7μM, respectively. Pentamidine displayed greater growth inhibition than all of the other tested compounds in a concentration- and time-dependent manner.

In this study, in silico and docking results were in accordance with the in vitro activity of the compounds. Moreover, EGCG and ECG showed reasonable levels of selectivity for Leishmania.