Author(s):
Machado, M. 
; Dinis, A. M. ; Santos-Rosa, M. ; Alves, V. ; Salgueiro, L. ; Cavaleiro, C. ; Sousa, M. C.
Date: 2014
Persistent ID: http://hdl.handle.net/10316/25521
Origin: Estudo Geral - Universidade de Coimbra
Subject(s): Leishmaniasis; Essential oil; Monoterpenes; Protozoa; Drug discovery; Apoptosis
Description
In the search for new leishmanicidal agents, Thymus capitellatus Hoffmanns. & Link (familyLamiaceae) volatile extract and its major compounds, 1,8-cineole and borneol, were testedagainst Leishmania infantum, Leishmania tropica and Leishmania major. Plant volatile extract(essential oil) was analysed by GC and GC–MS and the activity of essential oil on Leishmaniapromastigotes viability was assessed using tetrazolium-dye colorimetric method (MTT).The MTT test was also used to assess the cytotoxicity of essential oil on macrophages andbovine aortic endothelial cells. Effects on parasites were also analyzed by flow cytometryin order to assess mitochondrial transmembrane electrochemical gradient (JC-1), analyzephosphatidylserine externalization (annexin V–FITC, propidium iodide) and evaluate cellcycle (DNase-free, RNase, PI). Morphological and ultrastructural studies were performedby light, scanning and transmission electron microscopy. T. capitellatus volatile extractexhibited anti-parasite activity on Leishmania species, with IC50values ranging from 35to 62 g/ml. However, major compounds 1,8-cineole and borneol did not showed biologi-cal activity suggesting that these monoterpenes are not responsible for the antileishmanialactivity of T. capitellatus essential oil. Appearance of aberrant-shaped cells, mitochondrialswelling and autophagosomal structures were some of the ultrastructural alterations exhib-ited among treated promastigote cells. T. capitellatus promoted leishmanicidal effect bytriggering a programmed cell death as evidenced by externalization of phosphatidylserine,loss of mitochondrial membrane potential, and cell-cycle arrest at the G(0)/G(1) phase. Thevolatile extract did not induced cytotoxic effects on mammalian cells. Taken together, theseresults suggest that T. capitellatus may represent a valuable source for therapeutic controlof leishmaniasis in humans and animals. This work was supported by “Programa Opera-cional Ciência e Inovacão 2010 (POCI)/FEDER” da Fundac¸ ãopara a Ciência e Tecnologia (FCT).
