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Amebicidal activity of the essential oils of Lippia spp. (Verbenaceae) against Acanthamoeba polyphaga trophozoites

Santos, Israel Gomes de Amorim, Scher, Ricardo, Rott, Marilise Brittes, Menezes, Leociley Rocha, Costa, Emmanoel Vilaça, Cavalcanti, Sócrates Cabral de Holanda, Blank, Arie Fitzgerald, Aguiar, Jaciana dos Santos, da Silva, Teresinha Gonçalves, Dolabella, Silvio Santana
Parasitology research 2016 v.115 no.2 pp. 535-540
Acanthamoeba, Lippia alba, carvacrol, carvone, cleaning, cytotoxicity, drugs, encephalitis, essential oils, inhibitory concentration 50, keratitis, oils, parasites, protists, relapse, therapeutics, trophozoites
Amoebic keratitis and granulomatous amoebic encephalitis are caused by some strains of free-living amoebae of the genus Acanthamoeba. In the case of keratitis, one of the greatest problems is the disease recurrence due to the resistance of parasites, especially the cystic forms, to the drugs that are currently used. Some essential oils of plants have been used as potential active agents against this protist. Thus, the aim of this study was to determine the amebicidal activity of essential oils from plants of the genus Lippia against Acanthamoeba polyphaga trophozoites. To that end, 8 × 10⁴ trophozoites were exposed for 24 h to increasing concentrations of essential oils from Lippia sidoides, Lippia gracilis, Lippia alba, and Lippia pedunculosa and to their major compounds rotundifolone, carvone, and carvacrol. Nearly all concentrations of oils and compounds showed amebicidal activity. The IC₅₀ values for L. sidoides, L. gracilis L. alba, and L. pedunculosa were found to be 18.19, 10.08, 31.79, and 71.47 μg/mL, respectively. Rotundifolone, carvacrol, and carvone were determined as the major compounds showing IC₅₀ of 18.98, 24.74, and 43.62 μg/mL, respectively. With the exception of oil from L. alba, the other oils evaluated showed low cytotoxicity in the NCI-H292 cell line. Given these results, the oils investigated here are promising sources of compounds for the development of complementary therapy against amoebic keratitis and granulomatous amoebic encephalitis and can also be incorporated into cleaning solutions to increase their amebicidal efficiency.