Evaluation of anti-Toxoplasma effects of lipid nanoparticles carrying tea tree oil on Toxoplasma gondii tachyzoites in Vero cells

Toxoplasma gondii is a protozoan parasite that infects more than a third of the world’s population. The drugs used today to treat toxoplasmosis cause severe side effects in many people and have poor success in treating chronic infections. In the current study, oil extracted from tea leaf was loaded into solid lipid nanoparticles (SLNs) and its anti-Toxoplasma properties were analyzed. The double emulsification technique was employed to provide SLNs and their physical characteristics were assessed using transmission electron microscope (TEM) and dynamic light scattering (DLS). Cell toxicity and anti-intracellular Toxoplasma activity were investigated using a MTT assay. The anti-Toxoplasma activity of Tea tree oil (TTO)-SLNs was evaluated through trypan-blue staining. The TTO-SLNs were round with a mean particle size of 85.23 nm and clear and stable margins. An association was observed between the cell toxicity of TTO-SLNs with the concentration of the component (P-value = 0.009). The cytotoxic concentration (CC50) against Toxoplasma was > 10 mg/mL, while it was concentration-dependent (P-value < 0.0001). the viability of T. gondii- infected Vero cells were higher in lower concentrations of TTO-SLNs (P-value = 0.0174), while at least 80% of T. gondii- infected Vero cells remaining alive at concentrations greater than >1 mg/mL. Overall, our findings demonstrated high anti-T. gondii properties of TTO-SLNs, suggesting a promising role of SLNs in carrying TTO. In addition, our findings showed prolonged release of the TTO from SLNs capsulation of the can lead to, suggesting the potential of TTO-SLNs for applications in the chronic phase (cyst stages), which should be further investigated in animal models.