Effects of Extracts from Thai Piperaceae Plants against Infection with <i>Toxoplasma gondii</i>

<div><p>Herbal medicines and natural herb extracts are widely used as alternative treatments for various parasitic diseases, and such extracts may also have potential to decrease the side effects of the standard regimen drugs used to treat toxoplasmosis (sulfadiazine-pyrimethamine combination). We evaluated how effective the Thai piperaceae plants <i>Piper betle</i>, <i>P</i>. <i>nigrum</i> and <i>P</i>. <i>sarmentosum</i> are against <i>Toxoplasma gondii</i> infection <i>in vitro</i> and <i>in vivo</i>. Individually, we extracted the piperaceae plants with ethanol, passed them through a rotary evaporator and then lyophilized them to obtain crude extracts for each one. The <i>in vitro</i> study indicated that the <i>P</i>. <i>betle</i> extract was the most effective extract at inhibiting parasite growth in HFF cells (IC₅₀ on RH-GFP: 23.2 μg/mL, IC₅₀ on PLK-GFP: 21.4 μg/mL). Furthermore, treatment of experimental mice with the <i>P</i>. <i>betle</i> extract for 7 days after infection with 1,000 tachyzoites of the <i>T</i>. <i>gondii</i> PLK strain increased their survival (survival rates: 100% in 400 mg/kg-treated, 83.3% in 100 mg/kg-treated, 33.3% in 25 mg/kg-treated, 33.3% in untreated mice). Furthermore, treatment with 400 mg/kg of the <i>P</i>. <i>betle</i> extract resulted in 100% mouse survival following infection with 100,000 tachyzoites. The present study shows that <i>P</i>. <i>betle</i> extract has the potential to act as a medical plant for the treatment of toxoplasmosis.</p>