ANTHELMINTIC ACTIVITY OF SELECTED ALDEHYDES AND KETONES AGAINST SHEEP GASTRO-INTESTINAL NEMATODES

Abstract Text:

Ruminant gastrointestinal nematodes cause annually important economic losses to livestock production such as reduction of milk and meat yield. Because the resistance of parasites to conventional anthelmintic products is growing, studies evaluating the effectiveness of alternative products against gastrointestinal nematodes seem interesting. Compounds of botanical origin are considered as an important source of secondary metabolites with anthelmintic activity. This study was carried out to evaluate the nematicidal activity of aldehydes of plant origin such as furfural, 2-hydroxybenzaldehyde and (E,E)-2-4-decadienal and ketones such as 2-undecanone against gastrointestinal nematodes. Faecal samples were collected from the rectum of Sarda dairy ewes and worm eggs were identified by Mc Master technique, while the third stage larvae (L₃) of Strongyle type nematodes were obtained by coproculture after ten days. Larvaes were identified as Haemonchus contortus (24,7 %), Teladorsagia spp.(51,5%) and, Trichostrongylus spp. (23,8%). The larval development assay, by using Cellstar 96-well cell culture plates, was performed to evaluate the effects of the plant origin compounds against  L₃ larvaes. For calculation of EC₅₀ (mg/mL) inhibition effects, for the tested compounds on L₃ of gastrointestinal nematodes, the motility was assayed at concentration range of 0.28-5.99 mg/mL. Stock solutions were prepared in methanol whereas aqueous solution of tween ( 0.3% v/v) or 0.1 M phosphate- buffered saline solution (PBS) were used for further dilutions or as negative control. Each treatment consisted of 25 L₃ per well and was replicated six times. L₃ were analyzed after 1, 24 and 48 h with an inverted microscope 10x and were ranked into two categories: motile and immotile/paralyzed. The percentages of L₃ paralyzed were corrected by eliminating the natural death-paralysis in the negative control in according to the Schneider-Orelli formula. The 2-undecanone and (E,E)-2-4-decadienal showed the highest nematicidal activity with a EC_50/24h= 0.88 and 1.03 mg/mL respectively, while for furfural and 2-hydroxybenzaldehyde this concentration reference was 1.83 and 2.19 mg/mL, respectively. The experimental data revealed in vitro dose- dependent anthelmintic activity. However, the in vitro promising effects against gastrointestinal nematodes have to be carefully evaluated under in vivo conditions.

Keywords: parasite infection, in vitro, sheep