Background. Toxoplasma gondii is a common parasitic disease with a cosmopolitan prevalence, causing severe health problems. Although chemotherapy for toxoplasmosis is readily available, most have side effects. Objectives. This study assesses the Dracocephalum polychaetum essential oil against T. gondii activity. In vitro, the anti-Toxoplasma effects of D. polychaetum essential oils with different concentrations were evaluated. Methods. In the present study, T. gondii RH strain tachyzoites were exposed to D. polychaetum essential oil, and their viability effect on the parasite was evaluated. The viability test of tachyzoites was performed by using the staining method trypan blue in vitro. The inhibitory effect of D. polychaetum extract on T. gondii RH strain tachyzoites in the Vero cell line was evaluated. Results. D. polychaetum has valuable efficacy in vitro, outperforming pyrimethamine and sulfadiazine at 30 and 90 minutes after exposure ( p < 0.05 ). D. polychaetum essential oil showed anti-Toxoplasma activity in the cell line (IC50: 241.7 μg/mL). After T. gondii-infected Vero cells had been incubated with different concentrations of the D. polychaetum essential oil, their viability decreased in a dose-dependent manner. Conclusions. In conclusion, D. polychaetum extract as an herbal medicine might be a valuable alternative to routine chemotherapy for toxoplasmosis.

Background: Toxoplasma gondii is a parasite that lives inside its host cells, with cats reported as its final host. T. gondii causes toxoplasmosis infection, showing severe symptoms in infected fetuses and individuals with defective immune systems. Drugs used to treat toxoplasmosis have numerous side effects on patients, including toxicity and drug resistance. Objectives: This study aimed to investigate the same in vivo anti-Toxoplasma activity of Dracocephalum polychaetum essential oil. Moreover, this study aimed to investigate the effect of different concentrations of D. polychaetum essential oil on the survival rate of mice infected with T. gondii. Methods: The T. gondii RH strain was used in the present study. Moreover, 60 BALB/c mice aged 4 - 6 weeks with an average weight of 20 - 25 g were used to evaluate the in vivo anti-Toxoplasma effect of D. polychaetum essential oil. The BALB/c mice were divided into six groups of 10 cases. One negative control group received Phosphate buffered saline (PBS); two treatment groups received pyrimethamine (25 mg/kg) and sulfadiazine (500 mg/kg), and three other groups received 50, 100, and 200 mg/kg of essential oil, respectively. The data were analyzed with the Kaplan-Meier nonparametric method and log-rank test in SPSS software (version 16) at a significance level of 0.05. Results: The survival rate of the acutely infected mice was evaluated by the intraperitoneal injection of the essential oil (50, 100, and 200 mg/kg-1 day-1) infected with tachyzoites. There was no general significant difference between the mean survival rate of the studied groups (P > 0.05). However, essential oil and negative and positive controls that showed the best anti-Toxoplasma activity were assayed in triplicate at each concentration. Conclusions: A concentration of 200 mg/kg of D. polychaetum essential oil had a greater significant anti-Toxoplasma effect than other groups.