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Trypanosoma cruzi: inquiry on essential oils as potential trypanocidals agents.

by Santoro, Giani França

Abstract (Summary)
Nifurtimox and benznidazole, currently used for the treatment of Chagas disease, present several side effects and have limited efficacy, especially in thechronic phase of the disease. Several natural products have revealed anti-parasitic potential in the laboratory and, in this sense, plant-derived compounds appear aspotential targets for the development of new anti-parasitic drugs. Thus, in the present work we have investigated the effect of essential oils obtained from Origanumvulgare L. (oregano), Thymus vulgaris L. (thyme), Achillea millefolium L. (yarrow), Syzygium aromaticum L. (clove), Ocimum basilicum L. (basil) and Cymbopogon citratus (DC) Stapf (lemongrass), and of their main constituents, on proliferation and ultrastructure of Trypanosoma cruzi.Steam distillation was used to isolate the essential oils, with chemical analyses performed by gas chromatography C coupled to mass spectrometry (GC-MS) in collaboration with the Departamento de Química of UFLA (Lavras, MG).Epimastigotes and bloodstream trypomastigotes were incubated for 24 hours with different concentrations of the essential oils and with some of the main constituentsof the oils, being quantified the IC50/24h. Our data indicate that essential oils are effective against T. cruzi, presenting the following order of decreased activity on epimastigotes (IC50/24 h expressed as amp;#956;g/mL): thyme (77.0) gt; clove (99.5) gt; basil (102.0) gt; lemongrass (126.5) gt; yarrow (145.5) gt; oregano (175.0). In the assays withbloodstream trypomastigotes, the more active oils were: lemongrass (15.5) gt; thyme (38.0) gt; clove (57.5) gt; oregano (115.0) gt; yarrow (228.0) gt; basil (467.5). Thus, exceptfor basil and yarrow, the essential oils were more active on trypomastigotes than on epimastigotes.Treatment with the main constituents of lemongrass (citral), basil (linalool), clove (eugenol) and thyme (thymol) essential oils also demonstrated trypanocidaleffect. The lemongrass oil was effective in the treatment of infected macrophages, inhibiting intracellular amastigote proliferation, and presenting for the parameter % of infection an IC50/2 days of 12.1 amp;#956;g/mL. Flow cytometry experiments after incubation with oregano and thyme essential oils demonstrated that the cell membrane permeability of treated epimastigotes and trypomastigotes was affected only at concentrations at least 4 times higher than that of the corresponding IC50/24h. On the other hand, use of corresponding IC50/24h value for each essential oil did not result in cell permeabilization. Scanning electronmicroscopy (SEM) of treated cells demonstrated apparently no plasma membrane alteration with all used oils. However, there was swelling of the parasite body, as compared to control cells. Observation by transmission electron microscopy (TEM) showed cytoplasmic swelling, however with maintenance of the parasite membrane integrity, as compared to control cells. These data indicate that the oils permeate the membranes and act on cytoplasmic organelles or metabolic pathways. Thyme and lemongrass oils were much more active against the parasites when compared to the effect on peritoneal macrophages, pointing out to furtherassays of treatment of experimentally infected mice. Our results indicate that essential oils and their constituents are promising anti-T. cruzi agents, openingperspectives to the discovery of more effective drugs of vegetal origin for the treatment of parasitic diseases.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Maurilio José Soares

School:Faculdades Oswaldo Cruz

School Location:Brazil

Source Type:Master's Thesis

Keywords:Trypanosoma cruzi Antiprotozoal Agents/pharmacology Oils Volatile /pharmacology

ISBN:

Date of Publication:02/26/2007

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