In vitro and in vivo activity evaluation and mode of action of broxaldine on Toxoplasma gondii

Toxoplasma gondii (T. gondii) is a highly successful global parasite, infecting about one-third of the world's population and significantly affecting human life and the economy. However, current drugs for toxoplasmosis treatment have considerable side effects, and there is no specific drug to meet current needs. This study aims to evaluate the anti-T. gondii activity of broxaldine (BRO) in vitro and in vivo and explore its mechanism of action. Our results showed that compared to the control group, the invasion rate of tachyzoites in the 4 μg/mL BRO group was only 14.31%, and the proliferation rate of tachyzoites in host cells was only 1.23%. Furthermore, BRO disrupted the lytic cycle of T. gondii and reduced the size and number of cysts in vitro. A mouse model of acute toxoplasmosis reported a 41.5% survival rate after BRO treatment, with reduced parasite load in tissues and blood. The subcellular structure of T. gondii was observed, including disintegration of T. gondii, mitochondrial swelling, increased liposomes, and the presence of autophagic lysosomes. Further investigation revealed enhanced autophagy, increased neutral lipids, and decreased mitochondrial membrane potential in T. gondii treated with BRO. The results also showed a significant decrease in ATP levels. Overall, BRO demonstrates good anti-T. gondii activity in vitro and in vivo; therefore, it has the potential to be used as a lead compound for anti-T. gondii treatment.