Anthelmintic activity of extracts of Artemisia absinthium against ovine nematodes

The increasing prevalence of anthelmintic resistant strains of helminths, drug residues in animal products and high cost of conventional anthelmintics has created an interest in studying medicinal plants as an alternative source of anthelmintics. Artemisia absinthium Linn. (Tethwen) is used traditionally by people as a vermifuge in addition to its other livestock uses. The objective of this study was to evaluate the anthelmintic efficacy of crude aqueous extracts (CAE) and crude ethanolic extracts (CEE) of the aerial parts of A. absinthium in comparison to albendazole against the gastrointestinal (GI) nematodes of sheep. To fulfill the objectives, the worm motility inhibition assay was utilized in order to investigate the direct effects of plant extracts on the survival of the adult nematodes under in vitro conditions and faecal egg count reduction assay to investigate the effects on faecal egg output of GI nematodes under in vivo conditions. Significant anthelmintic effects of CAE and CEE on live adult Haemonchus contortus worms (P < 0.005) were observed in terms of the paralysis and/or death of the worms at different hours post-treatment (PT), however, CEE were more efficacious than CAE. The oral administration of the extracts in sheep was associated with significant reduction in faecal egg output by the GI nematodes. The CEE was as effective as the reference drug-albendazole and demonstrated faecal egg count reduction (FECR) of 90.46% in sheep at 2.0 g kg(-1) body weight on day 15 PT followed by 82.85% FECR at 1.0 g kg(-1) bw on day 15 PT. The CAE showed less activity and resulted in maximum of 80.49% FECR at 2.0 g kg(-1)bw. Dosage had a significant (P < 0.05) influence on the anthelmintic efficacy of A. absinthium. The better activity of CEE can be attributed to the greater concentration of alcohol soluble active anthelmintic principle/s and a more rapid transcuticular absorption of the CEE into the body of the worms when compared with the CAE. The results of the present study suggest that A. absinthium extracts are a promising alternative to the commercially available anthelmintics for the treatment of GI nematodes of sheep.