One of the limiting factors of sheep breeding is helminth infection, mainly resulting in poor weight gain. The combination of parasite control strategies, including the use of medicinal herbs can reduce the use of chemical anthelmintics. Tanniferous plants, by having phenolic compounds, mainly condensed tannins were associated with anthelmintic action. Fagopyrum esculentum Moench (buckwheat) has flavonoids, phenolic acids, tannins and high content of lysine, and the highest levels of these compounds are found in the seeds. Tannins exert direct anthelmintic action in reducing the the fertility of female nematodes, and indirect by increasing the immune response to protect the ingested protein of rumen degradation. The objective of this study was to evaluate the anthelmintic potential of the hydroalcoholic extract of F. esculentum Moench seeds (ETM) in the control of gastrointestinal nematodes of sheep in vitro and the antioxidant activity of ETM. Faeces from sheep presenting at least 2,000 eggs per gram of faeces were used. Hatchability and larvae migration tests were performed to evaluate the treatments ETM at concentrations of 0.625; 1.25; 2.5 and 5 mg mL-1, negative and positive controls and DMSO control (0.75% + distilled water). The treatment means were compared by Tukey test at 5% of probability. Subsequently, the total content of polyphenols, flavonoids, tannins and antioxidant activity of ETM were determined. For the conditions evaluated in this study, it was possible to verify anthelmintic activity of ETM in both tests in vitro. The ETM inhibited 19.66% of hatching in concentration 1.25 mg mL-1 and 17.66% of larvae migration in the concentration of 5 mg mL-1. The anthelmintic activity may be due to condensed tannin content found (288.89 mg equivalent tannic acid per gram of extract). Antioxidant activity was observed at all concentrations, reaching 38.71% at 3 mg mL-1 with IC50% = 3.83 mg mL-1 and 468.12 µM equivalent Trolox per gram of extract. At the same concentration to flavonoids and total polyphenols was observed respectively 31 mg equivalent rutin and 54.33 mg equivalent gallic acid per gram of extract. In addition to the direct effect of ETM on trichostrongylids of sheep, future research is also justified by the possibility of an indirect effect due to immune stimuli that protein diet provides on fostering in combating worms. It was concluded that it was possible to verify anthelmintic and antioxidant activity, demonstrating the potential of ETM in parasitological control of sheep.
Key words: Agroecology, buckwheat, condensed tannins, gastrointestinal nematodes, organic production, sheep breeding.