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-pyrimeth-
amine combination). We evaluated how effective the Thai piperaceae plants
Piper betle
,
P
.
nigrum
and
P
.
sarmentosum
are against
Toxoplasma gondii
infection
in vitro
and
in vivo
.
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
in vitro
study indicated that the
P
.
betle
extract was the most effective extract at inhibiting parasite
growth in HFF cells (IC
50
on RH-GFP: 23.2
μ
g/mL, IC
50
on PLK-GFP: 21.4
μ
g/mL). Further-
more, treatment of experimental mice with the
P
.
betle
extract for 7 days after infection with
1,000 tachyzoites of the
T
.
gondii
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
P
.
betle
extract resulted in
100% mouse survival following infection with 100,000 tachyzoites. The present study
shows that
P
.
betle
extract has the potential to act as a medical plant for the treatment o