In vitro schistosomicidal activity of triterpenoids from the African plant Momordica balsamina
Schistosomiasis, also known as bilharzia, is a chronic liver and intestinal parasitic disease caused by trematode worms of the genus Schistosoma. Praziquantel is the only available drug against all forms of schistosomiasis. The development of praziquantel resistance is a great concern and new drugs are urgently needed . Momordica balsamina L. (Cucurbitaceae), commonly known as African pumpkin, is a vegetable widespread in tropical and subtropical regions that has been used as food, mainly in sub-Saharan Africa. It has also been widely used in traditional medicine in Africa to treat various disease symptoms, mostly diabetes and malaria. In previous work, bioassay-guided fractionation of the methanol extract of the aerial parts of M. balsamina led to the isolation of several cucurbitane-type triterpenoids. Most of the isolated compounds as well their acylated derivatives displayed antimalarial activity [2, 3]. Continuing our search for antiparasitic compounds, the aim of this work was to evaluate the in vitro schistosomicidal activity of several triterpenoids isolated from M. balsamina against Schistosoma mansoni adult worms [4, 5]. Praziquantel was used as positive control. A remarkable schistosomicidal activity was observed for two of the ten compounds tested (at 50 and 100µM), which caused the death of all S. mansoni adult worms after 24h of incubation. Both compounds, at 10–50µM, induced significant reductions in the motor activity of the worms and significantly decreased the egg production. Furthermore, they were able (at 10–100µM) to separate the adult worm pairs into male and female after 24h.
Acknowledgement: This study was supported by FCT, Portugal (SFRH/BD/22321/2005) as well as Fapesp (2006/60132–4) and CNPq, Brazil
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