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Abstract
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Trichomoniasis is a protozoan disease caused by Trichomonas gallinae that mainly affects the upper
digestive and respiratory tracts of columbiforms. Metronidazole has been used for many years for the
control of trichomoniasis, however, in recent years, there were several reports on resistant T. gallinae
strains. Psidium guajava, a well-known medicinal plant species, possesses several biological activities
including anti-protozoal effects. Considering growing interest on plant and plant-derived compounds
as alternative sources of bioactive chemicals, the present study was performed to evaluate the
anti-trichomonal potential of P. guajava leave essential oil (EO) and its main components on T. gallinae
trophozoites. EO was extracted from plant fresh leaves by steam distillation using a Clevengertype
apparatus and gas chromatography-mass spectrometry was performed for identification of the
constituents. In vitro susceptibility assay was done in sterile multiwell plates incubated with the trophozoites
and the corresponding concentrations of tested compounds. Metronidazole was used as the
standard anti-trichomonal drug. Mortality rates were evaluated by eosin staining and recorded every
12 h for 2 days. The EO composition was dominated by the β-caryophyllene (30.2%) and α-pinene
(18.3%). A significant effect of concentration of the tested compound and time of exposure was noted
in the toxicity of the EO and its main constituents. Based on the 12 h fifty percent lethal concentrations
(LC50), β-caryophyllene was the most potent anti-trichomonal agent, with LC50 of 0.32 μg/mL.
Considering the natural source of β-caryophyllene and its reported low cytotoxicity and promising
anti-trichomonal efficacy, this compound can be considered as a candidate ingredient for the development
of green antitrichomonal agents.
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