In vitro anthelmintic activity of aqueous extract of Crassocephalum crepidioides (Benth.) S. Moore on Haemonchus contortus.

Abstract

Objectives: Gastrointestinal parasites are recognized as major constraint to livestock production throughout the tropics. The use of plants and plant extracts remain the most serious alternative to modern anthelmintic drugs. This study evaluates the in vitro anthelmintic activity of aqueous leaves extract of Crassocephalum crepidioides against Haemonchus contortus. Methods: Aqueous extract at concentrations of 75 to 2400 µg/ml was tested in vitro on three development stages of H. contortus using egg hatch assay (EHA), larval migration inhibition assay (LMIA) and adult worms motility inhibition assay (AMIA). Results: EHA showed significant reduction (P < 0.05) on H. contortus egg hatch. The inhibition of egg hatching was concentration dependent with the greatest inhibition (50.52%) at the highest concentration (2400 µg/ml) of the extract. Thiabendazole used as positive control showed significant inhibition (P < 0.001) with rate of 76.68 % at the highest concentration (500µg/ml). On LMIA the extract significantly (P < 0.05) inhibited larval migration of L3 in a concentration dependent manner compared to Phosphate Buffered Saline, but less than levamisole (P < 0.001). The highest inhibition rate was 35.30 % at the concentration of 1200 µg/ml. The addition of polyvinylpolyrrolidone to the aqueous extract slightly reduces (4.9%) the inhibition of the effect induced by the extract on larval migration. Effect of extract on AMIA was concentration-dependent with significant increase (P < 0.05) in percentage of inhibition after 12 h. Levamisole (500 µg/ml) kills 100% worms after 18 h post-exposure but by this time the plant exhibited only 16.67% inhibition at the highest concentration (2400 µg/ml). Conclusion: These finding indicate that C. crepidioides leaves have anthelmintic properties against H. contortus. This activity may be due to secondary metabolites such as saponins, flavonoids and tannins present in the extract. Further studies are needed to evaluate deeply the anthelmintic potential of this plant.