Mode of action of the sesquiterpene lactone deoxymikanolide on Trypanosoma cruzi

LAURELLA L; ALONSO MR; SÜLSEN V; PUENTE V; SOSA M; SPINA R; MARTINO V; MARTINO V

Bogotá

Congreso; 3rd Research Network Natural Products against Neglected Diseases - ResNet NPND Scientific Meeting 2016; 2016

Universidad Militar de Nueva Granada - ResNet

Chagas´ disease is caused by the protozoan Trypanosoma cruzi. Approximately 6?7 million people are infected and other 25 million are at risk of contamination [1]. Thus, a disease that was traditionally limited to Latin America has now crossed these boundaries and expanded worldwide.Sesquiterpene lactones are a group of natural compounds, mainly found in the Asteraceae family, which show interesting biological activities such as antitumor, antiinflammatory, antibacterial, antiparasitic and others [2].We have demonstrated previously the trypanocidal activity of deoxymikanolide, a sesquiterpene lactone isolated from Mikania micrantha (Asteraceae). The aim of this study was to provide an insight into the mechanism of action of this active compound.To determine if deoxymikanolide produced an oxidative stress in the parasites upon treatment, reactive oxygen species (ROS) generation was evaluated. The intracellular oxidative activity was assessed by flow cytometry using the oxidant-sensitive fluorescent probe H2DCFDA. The activity of superoxide dismutase (SOD) and trypanothione reductase (TryR) and the total thiol groups content were carried on. Transmission electron microscopy of treated parasites was also performed.A slight increase in ROS production in epimastigotes was observed after 8 h of treatment with deoxymikanolide (MIF: 15), although the frequency of DCF+ parasites was 80% (MFI: 21) upon H2O2 incubation. By the contrast, after 24 h treatment, fluorescent DCF increased to 74 % (MIF: 34). Significant changes in the enzymes activity and in the content of thiol groups were observed respect to untreated epimastigotes at any of the times tested. Significant ultrastructural alterations were observed on T. cruzi epimastigotes after treatment with deoxymikanolide. Approximately 30% of epimastigotes displayed double or strechted kinetoplast and / or double flagellum with a concentration of 0.1 µg/ml. At concentration of 2.5 µg/ml the compound induced an intense vacuolization. This work was performed in order to provide a biochemical characterization of deoxymikanolide´s antitrypanosomal mechanism of action. Other possible assays such as hemin interaction, effect on mitochondrial enzymes and membrane, ergosterol biosynthesis, induction of parasite death will be performed on in order to elucidate its mode of action.Keywords: deoxymikanolide, sesquiterpene lactone, Trypanosoma cruzi, mechanism of actionAcknowledgements: This work was supported by grants from PICT 1753 (2012-2015) (The National Agency for Science and Technology Promotion), PIP 0324 (National Scientific and Technical Research Council), and UBACYT 20020130200270 (University of Buenos Aires).References[1] World Health Organization 2016. Fact sheet Chagas disease (American trypanosomiasis). http://www.who.int/mediacentre/factsheets/fs340/en/. Accessed August 2016.[2] Chaturvedi D, 2011. Sesquiterpene lactones: Structural diversity and their biological activities, in: Opportunity, Challenge and Scope of Natural Products in Medicinal Chemistry, Research Signpost , Kerala, India. pp 313-334.