ABSTRACT
Haemonchus contortus is a major health and welfare problem for small ruminants, responsible for economic losses through reduced productivity and increased mortality. The in vitro efficacy of Bidens pilosa was determined against this gastrointestinal nematode (GIN). Fresh eggs, embryonated eggs and larvae (L1 and L2) were incubated at room temperature in infused aqueous extract, macerated aqueous and ethanolic leaf extract of B. pilosa at concentrations of 0.625, 1.25, 2.5, 3.75 and 5 mg/ml for 48, 6 and 24 hours, respectively. Distilled water and 1.5% Tween 80 were used as negative controls. They did not affect development of eggs and larvae whereas extracts showed a concentration dependent activity eventhough aqueous extracts exhibited a weak activity on the different developmental stages of H. contortus compared to ethanolic extract. Ethanolic extract was more potent on larvae than on eggs. It inhibited 92.5±7.5% and 67.4±7.4% egg embryonation and egg hatch at 5 mg/ml, with IC50 values of 2.1 mg/ml and 3.3 mg/ml respectively and induced 100±0% and 89.8±3.2% L1 and L2 larvae mortality at 5 mg/ml with LC50 values of 1.8 and 1.96 mg/ml respectively. The overall findings of the current study indicated that the evaluated medicinal plant in occurrence B. pilosa possess potential anthelmintic effect and further in vivo and toxicity evaluation are indispensable to validate its use as anthelmintic for the control of GIN.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the ovicidal and larvicidal activities of aqueous and ethanolic extracts of leaves of Dichrocephala integrifolia (D. integrifolia) against the eggs (fresh and embryonnated), the first and second larval stages of Heligmosomoides bakeri. In order to verify if this medicinal plant possesses active compounds capable of inhibiting the embryonation and hatching of eggs or to induce the mortality of larvae (L1 and L2).</p><p><b>METHODS</b>dried extracts were diluted in distilled FIV water to obtain five different concentrations: 625, 1,250, 2,500, 3,750 and 5,000 µg/mL. Fresh eggs obtained from artificially infected mice feces were exposed to these different concentrations for 48 h. Time of contact for embryonated eggs was 6 h while L1 and L2 larvae were exposed for 24 h. Distilled water (placebo) and 1.5% DMSO were used as negative controls.</p><p><b>RESULTS</b>Distilled water, and 1.5% DMSO had no effect on embryonation, hatching and larval survival. Aqueous extracts of D. integrifolia showed a weak activity against all stages of the parasite at all concentrations tested. On the contrary, the ethanolic extract of D. integrifolia inhibited the embryonation of 87.5% of fresh eggs, the hatching of 81.1% of embryonated eggs and induced the mortality of 98.1% and 98% of L1 and L2 larvae respectively at 5,000 µg/mL.</p><p><b>CONCLUSIONS</b>The results of the present study indicate that the ethanolic extracts of D. integrifolia contained compounds with ovicidal and larvicidal properties. In spite of these results, in vivo tests, studies on toxicity and mechanism of action of active compounds are also needed to validate the utilisation of this medicinal plant by population of Dschang-Cameroon to treat gastro-intestinal parasites.</p>