In vivo anthelmintic activity of hydroethanolic extract of grape pomace in sheep naturally infected with gastrointestinal nematodes

Infections by gastrointestinal nematodes, particularly Haemonchus contortus , cause significant losses in sheep production, leading to anemia and mortality. Control relies on synthetic anthelmintics, but resistance has prompted research into plant-based alternatives. The objective of this study was to evaluate the anthelmintic activity, and hepatotoxicity of the hydroalcoholic grape pomace extract in in vivo assays using sheep naturally infected with gastrointestinal nematodes. In addition to the in vivo evaluation, qualitative analyses were performed to determine the phytochemical classes, as well as to determine the phenolic and tannin content present in the extract. Phytochemical screening, analyses of ultraviolet-visibles and Folin–Ciocalteu colorimetric method were used for qualitive chemical determination. High-performance liquid chromatography (HPLC) analyses identified and quantified some of the phenolic compounds in the extract. To in vivo assays, thirty animals were divided into three groups: one treated with levamisole hydrochloride 5% (RIPERCOL® L Solution) (5 mg/kg), one with grape pomace extract (500 mg/kg on days 0 and 14), and a control group. Fecal egg counts (FEC) were assessed on days 0, 7, 14, 21, 28, 35, and 42. Blood samples from the extract-treated group were analyzed for γ-glutamil transferase and aminotransferase levels to assess toxicity. Coproculture identified nematode species with a predominance of Haemonchus spp. The extract-treated group showed >90% FEC reduction from day 14, peaking at 98% on day 28. By day 35, FEC reduction was 95%, comparable to levamisole. A slight FEC increase occurred by day 42 in both groups, with no statistical differences between the levamisole and extract groups. Liver function tests revealed no toxicity. The qualitative phytochemical analysis detected the presence of saponin, tannin, and flavonoids in the hydroethanolic extract of grape pomace. The total phenolic and tannin content were, respectively, 27.7 mg tannic acid equivalents per gram of dry extract and 13.3 mg tannic acid equivalents per gram of dry / extract. The phenolic compounds found in highest proportion were gallic acid and resveratrol. Hydroethanolic extract of grape pomace demonstrated in vivo anthelmintic activity against gastrointestinal nematodes in sheep without causing toxicity, confirming the safety of its use at the evaluated dose.