Remarkable anti-trichomonas vaginalis activity of plants traditionally used by the Mbyá-Guarani indigenous group in Brazil

Abstract

Trichomonas vaginalis, a flagellate protozoan, is the causative agent of trichomonosis, the most common nonviral sexually transmitted disease worldwide. Taking into account the increased prevalence of metronidazole-resistant isolates, alternative drugs are essential for the successful treatment. Natural products are the source of most new drugs, and popular wisdom about the use of medicinal plants is a powerful tool in this search. In this study, the activity of 10 medicinal plants extensively used in daily life by Mbyá-Guarani indigenous group was evaluated against seven different T. vaginalis isolates. Among the aqueous extracts tested, Verbena sp. (Guachu ka'a in Mbyá-Guarani language) and Campomanesia xanthocarpa (Guavira in Mbyá-Guarani language) showed the highest activity against T. vaginalis with MIC value of 4.0 mg/mL reaching 100% of efficacy against the parasite. The kinetic growth assays showed that the extracts promoted complete growth abolishment after 4 h of incubation. In addition, the extracts tested did not promote a significant hemolytic activity against human erythrocytes. Our results show for the first time the potential activity of Verbena sp. and C. xanthocarpa against T. vaginalis. In addition, this study demonstrates that indigenous knowledge is an important source of new prototype antiprotozoal agents.

Figure 1

Effect of selected Mbyá-Guarani medicinal plants at 4.0 mg/mL on different Trichomonas vaginalis isolates. (a) Verbena sp. (b) Campomanesia xanthocarpa. (c) Bidens pilosa. (d) Luehea divaricata. (e) Coix lacryma-jobi. (f) Trichilia sp. (g) Citrus limonium. (h) Aloe arborescens. (i) Citrus reticulata. (j) Rhipsalis baccifera. Data represent means ± standard deviation.

Figure 2

Kinetic growth curve of Trichomonas vaginalis 30236 isolate after treatment with aqueous extracts of Verbena sp. and Campomanesia xanthocarpa at 4.0 mg/mL. The trophozoites growth was completely inhibited by the extracts in 4 hours of incubation. Data represent means ± standard deviation of at least three experiments, all in triplicate.

Figure 3

Microscopic analysis of parasites morphology in light microscope (magnified ×1,000) by trypan blue dye exclusion. (a) Control; (b) after 4 hours of treatment with aqueous extract of Verbena sp.; (c) after 4 hours of treatment with aqueous extract of Campomanesia xanthocarpa.