In vitro evaluation of anti-trichomonal potential of Psidium guajava leaf essential oil and its main components against trophozoites of Trichomonas gallinae

Abstract

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 Clevenger-type 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.