Anthelmintic activity of plants against gastrointestinal nematodes of goats: a review.

The gastrointestinal nematodes (GIN) stand out as an important cause of disease in small ruminant, especially on goat farm. Widespread resistance to synthetic anthelminthics has stimulated the research for alternative strategies of parasite control, including the use of medicinal plants. The present work summarizes the in vitro and in vivo studies of plants with activity against GIN of goats, focusing on the description of chemical constituents related to this effect. This review retrieved 56 scientific articles from 2008 to 2018 describing more than 100 different plant species. The most frequently investigated family was Fabaceae (30.7%). Most in vitro studies on the activity of plant extracts and fractions were carried out with of free-living stages nematodes. In vivo studies were conducted mainly with the use of plants in animal feed and generally showed lower effectiveness compared to in vitro assays. The main plant secondary metabolites associated with anthelmintic effect are condensed tannins, saponin and flavonoids. However, the studies with compounds isolated from plants and elucidation of their mechanisms of action are scarce. Herbal medicines are thought to be promising sources for the development of effective anthelmintic agents.

Atividade anti-helmíntica do extrato aquoso das folhas de Zanthoxylum rhoifolium Lam. (Rutaceae)

The study evaluated the anthelmintic activity of aqueous extract of Zanthoxylum rhoifolium leaves in two experiments. In vitro test, cultures of goat fecal samples were treated with different concentrations of extract (134.5 to 335.0 mg.mL-1). In vivo test was composed of 20 sheep: G1: treated with 0.63 g.kg-1, during four days; G2: same dose, for eight days; G3: ivermectin (200 g.kg-1) and G4 untreated group. In vitro results showed a reduction of Haemonchus spp, Trichostrongylus spp. and Oesophagostomum spp. larvae greater than 95% in the concentrations between 335.0 and 193.7 mg.mL-1. Faecal egg counting reduction was 51, 56 and 90% in G1, G2 and G3, respectively, while immature stages and adults ranged from 0 to 91% in G1 and from 26 to 94% in G2. Ivermectin effectiveness was 99% for L4 and L5 of H. contortus and 100% for other nematodes species. Clinical and biochemical parameters have remained in the normality and histophatologic analyses did not show alteration suggesting absence of toxicity. Although the great effectiveness of Z. rhoifolium leaves extract in vitro test, it displayed poor efficiency in vivo regarding gastrointestinal nematodes reduction.

O estudo avaliou a atividade anti-helmíntica do extrato aquoso das folhas de Zanthoxylum rhoifolium em dois experimentos. O teste in vitro utilizou cultivos de fezes de caprinos tratados com diferentes concentrações do extrato: (134,5 a 335,0 mg.mL-1). No teste in vivo, utilizaram-se 20 ovelhas: G1 tratado durante quatro dias (0,63 g.kg-1 PV); G2, mesma dose, por oito dias; G3, ivermectina (200 g.kg-1); e G4, sem tratamento. In vitro, observou-se redução de larvas de Haemonchus, Trichostrongylus e Oesophagostomum superior a 95% nas concentrações de 193,7 a 335,0 mg.mL-1. In vivo, a redução de ovos por grama de fezes foi de 51, 56 e 90%, respectivamente, para G1, G2 e G3, no oitavo dia de tratamento, enquanto para os estágios imaturos e adultos variou de 0 a 91% no G1 e 26 a 94% no G2. A eficácia da ivermectina alcançou 99% para L4 e L5 de H. contortus e 100% para as demais espécies de nematoides. Parâmetros clínicos e bioquímicos permaneceram na faixa de normalidade, e as análises histopatológicas não revelaram alterações sugestivas de toxicidade. Embora altamente efetivo in vitro, o extrato aquoso de folhas de Z. rhoifolium foi pouco eficaz in vivo na redução de nematoides gastrintestinais.