Antileishmanial Activity and Cytotoxicity in U937 cells of Essential Oils From Aromatic Plants Commonly Used in Traditional Medicine

The essential oils from aromatic plants Rosmarinus officinalis, Mentha piperita, Schinus molle, Cinnamomum zeylanicum, Citrus sinensis, Pinus pinea, Lavandina abrial, Hyssopus officinalis, Lippia alba, Cimbopogon nardus, Eletaria cardamomum and Aloysia polystachya are used in traditional medicine because their antibacterial and anti-inflammatory properties. However, there are no available reports of activity against Leishmania parasites. In the present study we evaluated the antileishmanial activity and cytotoxicity of essential oils extracted from these plants. The essential oils were solubilized in DMSO not exceeding 0.5%. The cytotoxicity was evaluated on U-937 macrophages using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) colorimetric method while the antileishmanial activity was evaluated on L. panamensis amastigotes by flow cytometry. The results are expressed as median Lethal Concentration (LC₅₀) for cytotoxicity and median Effective Concentration (EC₅₀) for effectiveness, both values calculated by Probit [1]. The most effective essential oil were M. piperita and S. molle with an EC₅₀ < 3 and 15.2 mg/mL, respectively while E. cardamomun showed moderate antilaeishmanial activity (EC₅₀ 43.9 mg/mL). None of the essential oils was cytotoxic to the U-937 cells. This is the first report of antileishmanial activity to M. piperita, S. molle and E. cardamomun. Since the essential oils of these plants with high or moderate antileishmanial activity are traditionally used for management of skin lesions, the development of a formulation that combines the antileishmanial and anti-inflammatory properties could be a possible alternative for the management of uncomplicated cutaneous leishmaniasis.

[1] Duque-Benítez SM, Ríos-Vásquez LA, Ocampo-Cardona R, Cedeño DL, Jones MA, Vélez ID, Robledo SM. Molecules 2016; 21:381.