Atividade in vitro de óleos essenciais sobre Trypanosoma evansi

Abstract

Trypanosoma evansi is a hemoprotozoal transmitted mechanically by hematophagous insects and is found in the bloodstream of hosts in the trypomastigote form. With a cosmopolitan distribution and economic importance in Africa, Asia and Latin America, this trypanosome can infect numerous species of domestic and wild animals, causing in horses the disease called "Surra" or "Mal das Cadeiras". In Brazil, the drugs available to treat this disease are diminazene aceturate and isometamidium chloride, however, in addition to presenting hepatotoxicity and nephrotoxicity, it does not always eliminate the parasite. In some cases, parasitaemia recurrence after treatment, which may be related to the impossibility of the drug crossing the blood-brain barrier or the emergence of drug-resistant strains. Essential oils are increasingly being studied for the control of microorganisms, and the trypanocidal activity of various oils has been demonstrated. In this context, the objective of this study was to evaluate the efficacy in vitro treatment of the essential oils Citrus bergamia, Cinnamomum zeylanicum, Cymbopogon citratus, Cedrus atlantica, Eucalyptus globulus, Zingiber officinale and Thymus vulgaris against Trypanosoma evansi trypomastigotes. T. evansi isolate (LPV-2005) used in this study was originally isolated from a naturally infected dog, and kept cryopreserved in liquid nitrogen under laboratory conditions. The parasites maintained in culture medium were distributed in microtiter plates (270 μL / well), followed by the addition of the essential oil, previously diluted in DMSO, at concentrations of 0.5%, 1.0% and 1.5% and kept in an oven (at 5 % CO2 and 37 ° C). DMSO, mineral oil, culture medium and diminazene aceturate were used as control groups. The tests were performed in duplicate and the parasites were counted in the Neubauer chamber 1, 3 and 6 h after the onset of the experiment. The essential oils were quantified and qualified. Our study demonstrated that essential oils bergamot (C. bergamia), cinnamon (C. zeylanicum), lemon grass (C. citratus), cedar (C. atlantica), eucalyptus (E. globulus), ginger (Z. officinale) and thyme (T. vulgaris) trypanocidal activity in vitro against T. evansi trypomastigotes. However, when compared with each other and with diminazene aceturate, the essential oils of C. zeylanicum, E. globulus, Z. officinale and T. vulgaris demonstrated greater in vitro efficacy against T. evansi trypomastigotes. Based on the results found, we can conclude that essential oils may be promising alternatives for the treatment of trypanosomes.