Effects of Myracrodruon urundeuva extracts on egg hatching and larval exsheathment of Haemonchus contortus

Abstract

The anthelmintic resistance has limited the control of gastrointestinal nematodes of small ruminants and thus has awakened interest in the study of tanniferous plants as a source of anthelmintics. These experiments were carried out to evaluate the in vitro efficacy of Myracrodruon urundeuva leaf extract (LE) and stem extract (SE) against Haemonchus contortus. An inhibitor of tannins, polyvinyl polypyrrolidone (PVPP), was used to verify if these metabolites are involved in the anthelmintic activity of the extracts. To evaluate the ovicidal effect, H. contortus eggs were incubated with the extracts (0.31 to 5 mg/mL) for 48 h. In the larval artificial exsheathment assay, third-stage larvae of this nematode were incubated with extracts (0.31 mg/mL) for 3 h and then were exposed to a sodium hypochlorite solution. The exsheathment process was evaluated for 60 min. The results were subjected to the Kruskal-Wallis test (P < 0.05). The extracts showed dose-dependent ovicidal effects, although the LE was more effective, inhibiting egg hatching by 97.73% at 1.25 mg/mL, while the SE inhibited hatching by 83.56% at 5 mg/mL. Contact with the extracts blocked the larval exsheathment (P < 0.05). The addition of PVPP confirmed the role of tannins, as there was a substantial reduction in egg hatching and larval exsheathment percentage. These results suggest that M. urundeuva can be used to control gastrointestinal nematodes of small ruminants and that the anthelmintic activity of this plant is probably related to tannins; however, in vivo studies should be conducted.