Evaluation of the efficicacy of myrcene in the treatment of <i>Eimeria tenella</i> and <i>Toxoplasma gondii</i> infection

Protozoan parasites such as Eimeria tenella and Toxoplasma gondii pose significant health challenges in livestock and humans. The limited treatment options and rising drug resistance underscore the urgent need for new therapies. This study investigates myrcene, a monoterpene hydrocarbon classified for its antiprotozoal potential against E. tenella and T. gondii infections. Initially, we examined its effect on the sporulation process of E. tenella oocysts in vitro and its anti-E. tenella activity in vivo. Myrcene significantly reduced the sporulation rate of E. tenella oocysts at 3 and 4 mg/kg. In vivo experiments demonstrated that treatment with 4 mg/kg myrcene significantly reduced E. tenella load and oocyst output, as well as cecal lesion and weight loss caused by E. tenella infection, showing moderate anti-E. tenella activity, with an Anticoccidial Index (ACI) of 161.4. Furthermore, we investigated the anti-T. gondii activity of myrcene both in vitro and in vivo. In vitro studies showed that treatment with myrcene effectively inhibited the invasion rate and intracellular proliferation ability of T. gondii tachyzoite in DF-1 cells in a dose-dependent manner. In vivo administration prolonged the survival time in T. gondii-infected mice, suggesting notable protective effects. Additionally, it mitigated T. gondii-induced hepatosplenic toxicity by reducing parasite load in the liver and spleen, and ameliorating liver function as evidenced by decreased serum transaminase levels. In conclusion, the findings demonstrate promising anti-E. tenella and anti-T. gondii activity exhibited by myrcene warranting further exploration into its mechanisms and potential therapeutic applications.