Anthelmintic activity of Eucalyptus staigeriana encapsulated oil on sheep gastrointestinal nematodes.

The anthelmintic activity of Eucalyptus staigeriana essential oil has previously been inferred through both in vitro and in vivo tests. Thus, the encapsulation process generally improves oil stability, promotes controlled release in target organs, reduces dosage, and increases efficacy. The aims of this study were to analyze and encapsulate E. staigeriana essential oil and to verify its anthelmintic activity in sheep. The encapsulation process was accomplished through emulsion using a 4% chitosan solution as the matrix. Anthelmintic activity was established through controlled testing using 18 sheep that were separated into three groups: group 1 was treated with a single dose of 365 mg/kg of E. staigeriana encapsulated oil, group 2 was treated with 200 µg/kg of ivermectin, and group 3 was treated with a 4% chitosan solution as a negative control. The sheep were euthanized and necropsied 13 days posttreatment to evaluate worm burden. Limonene was the major oil component (72.91%). The final product was a hydrogel with 36.5% (m/m) E. staigeriana essential oil per gram. Its efficacy on gastrointestinal nematodes was 60.79%. The highest efficacy was against abomasal nematodes, with 83.75% efficacy. Further studies are necessary to explore the possibility of increasing the hydrogel efficacy; nevertheless, we can state that E. staigeriana encapsulated oil had anthelmintic activity and can be used in gastrointestinal nematode control.

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

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.