Combination of the essential oil constituents citral, eugenol and thymol enhance their inhibitory effect on Crithidia fasciculata and Trypanosoma cruzi growth

Abstract

We analyzed the effect of the combination of citral, eugenol and thymol, respectively the main constituents of essential oils of Cympobogon citratus (DC) Stapf, Poaceae (lemon grass), Syzygium aromaticum (L.) Merr. & L.M. Perry, Myrtaceae (clove) and Thymus vulgaris L., Lamiaceae (thyme), on the proliferation of the trypanosomatids Crithidia fasciculata and Trypanosoma cruzi. The constituents were initially added individually at different concentrations to C. fasciculata cultures to estimate the IC50/24h. Concentrations in a triple combination were about 2 times and 16.5 times lower against C. fasciculata and T. cruzi, respectively, as compared to isolated compounds. Incubation of C. fasciculata with the trypanocydal agent benznidazole did not affect parasite growth at concentrations up to 500 μg/ml, but the IC50 of this drug against T. cruzi was 15.8 μg/ml, a value about 2–5 times higher than that of constituents in the triple combination. Analysis of treated C. fasciculata by scanning electron microscopy showed rounding of the cell body. Our data show that combination of essential oil constituents resulted in increased inhibitory activity on growth of both non-pathogenic and pathogenic trypanosomatid species and indicate that the non-patogenic C. fasciculata may represent a resistant model for drug screening in trypanosomatids.