Trematode infections negatively affect human and livestock health, and threaten global food safety. The only approved human anthelmintics for trematodiasis are triclabendazole and praziquantel with no alternative drugs in sight. We tested six crude plant extracts against adult Schistosoma mansoni, Fasciola hepatica, and Echinostoma caproni in vitro. Mortality was best achieved by ethanolic extracts of Artemisia annua (sweet Annie), Asimina triloba (paw-paw), and Artemisia absinthium (wormwood) which, at 2 mg/mL, killed S. mansoni and E. caproni in 20 h or less (except for wormwood), F. hepatica between 16 and 23 h (sweet Annie), or 40 h (paw-paw). Some extracts were active at 0.2 mg/mL and 20 μg/mL, although more time was required to kill trematodes. However, aqueous A. annua and methanol extracts of Fumaria officinalis had no activity. Chromatographic analysis of the three best extracts established that A. annua and A. triloba extracts contained bioactive artemisinin and acetogenins (asimicin and bullatacin), respectively. The anthelmintic activity of our extracts at such low doses indicates that their anthelmintic activity deserves further testing as natural alternative controls for parasites of both animals and humans. Our results also support recent evidence that synergistic effects of multiple bioactive compounds present in crude plant extracts is worth exploring.

The paw paw tree, Asimina triloba (L.) Dunal (Annonaceae), contains more than 50 bioactive components, primarily annonaceous acetogenins. Some therapeutic activities have been associated with this material, but the potential to mediate a cancer chemopreventive effect has not been reported. In this study, a standardized extract from the twigs, in which bullatacin, asimicin, and trilobacin represent the most potent and major bioactive acetogenins, was tested in the N-methyl-N -nitrosourea-induced mammary carcinogenesis model. With Sprague-Dawley rats given a diet containing paw paw extract (1250 and 2500 mg/kg diet; based on maximum tolerated dose studies), mammary tumor latency was increased from 55 to 66 days. However, mammary tumor incidence and multiplicity were not affected by extract consumption.