Myrtus communis Essential Oil; Anti-Parasitic Effects and Induction of the Innate Immune System in Mice with Toxoplasma gondii Infection

Background: Myrtus communis (M. communis) is a wild aromatic plant used for traditional herbal medicine that can be demonstrated in insecticidal, antioxidant, anti-inflammatory, and antimicrobial activity of its essential oils (MCEO). Aim: The present study aimed to evaluate the prophylactic effects of M. communis essential oil (MCEO) against chronic toxoplasmosis induced by the Tehran strain of Toxoplasma gondii in mice. Methods: Gas chromatography/mass spectrometry (GC/MS) analysis was performed to determine the chemical composition of MCEO. Mice were then orally administrated with MCEO at the doses of 100, 200, and 300 mg/kg/day and also atovaquone 100 mg/kg for 21 days. On the 15th day, the mice were infected with the intraperitoneal inoculation of 20-25 tissue cysts from the Tehran strain of T. gondii. The mean numbers of brain tissue cysts and the mRNA levels of IL-12 and IFN-gamma in mice of each tested group were measured. Results: By GC/MS, the major constituents were alpha-pinene (24.7%), 1,8-cineole (19.6%), and linalool (12.6%), respectively. The results demonstrated that the mean number of T. gondii tissue cysts in experimental groups Ex1 (p < 0.05), Ex2 (p < 0.001) and Ex3 (p < 0.001) was meaningfully reduced in a dose-dependent manner compared with the control group (C2). The mean diameter of tissue cyst was significantly reduced in mice of the experimental groups Ex2 (p < 0.01) and Ex3 (p < 0.001). The results demonstrated that although the mRNA levels of IFN-gamma and IL-12 were elevated in all mice of experimental groups, a significant increase (p < 0.001) was observed in tested groups of Ex2 and Ex3 when compared with control groups. Conclusion: The findings of the present study demonstrated the potent prophylactic effects of MCEO especially in the doses 200 and 300 mg/kg in mice infected with T. gondii. Although the exceptional anti-Toxoplasma effects of MCEO and other possessions, such as improved innate immunity and low toxicity are positive topics, there is, however, a need for more proof from investigations in this field.