Anti-Toxoplasma and Antioxidant Activity of a Terpene and Methyl-Ester-Rich Subfraction from Pleopeltis crassinervata

<i>Pleopeltis crassinervata</i> has demonstrated antimicrobial effects, including anti-<i>Toxoplasma</i> activity, which has been attributed to the presence of compounds such as terpenes and fatty acid methyl esters. In this study, the effects of <i>P. crassinervata</i> hexane subfraction one (Hsf1) on the <i>Toxoplasma gondii</i> tachyzoite ultrastructure were evaluated using TEM and SEM, and lytic cycle processes such as adhesion, invasion, and proliferation were evaluated using phase-contrast microscopy. Additionally, the antioxidant capacity of the subfraction and its main compounds (phytol and hexadecenoic acid methyl ester) were determined as well as their effects on parasite viability. Hsf1 exhibited a dose-dependent inhibitory effect on the lytic process at a concentration of 47.2 µg/mL. Among the eighteen compounds identified in this subfraction, six were evaluated, of which two (phytol and hexadecanoic acid methyl ester) significantly reduced the viability of <i>T. gondii</i> to 0.11% and 16.6%, respectively, at a concentration of 100 µg/mL. Additionally, Hsf1 demonstrated an antioxidant capacity of 30% as assessed using the ORAC method. The two active compounds also exhibited antioxidant properties, with antioxidant capacities of 13.33% and 33% for hexadecanoic acid methyl ester and phytol, respectively, at concentrations up to 15.4 mg/mL. Hsf1 showed membrane damage and conoid extrusion in <i>T. gondii</i> tachyzoites, suggesting direct interference with the lytic cycle of the parasite. These findings underscore the therapeutic potential of Hsf1 as a promising tool for controlling infections caused by <i>T. gondii</i>, thereby providing an alternative in the search for new antiparasitic agents. However, further research is required to determine the in vivo pharmacological effects and properties of these compounds with potential anti-<i>Toxoplasma</i> activity.