Eficacia antiparasitaria in vitro del extracto de quebracho (Schinopsis balansae) sobre larvas infectantes de Haemonchus contortus de ovinos / In vitro antiparasitic efficacy of the quebracho extract (Schinopsis balansae) on infecting larvae of Haemonchus contortus of sheep

RESUMEN El objetivo de este trabajo fue evaluar in vitro la eficacia del extracto de quebracho (Schinopsis spp.), rico en taninos condensados, en el control de H. contortus de ovinos, ya que existen evidencias de que estos taninos pueden reducir la excreción de huevos, la fecundidad de las hembras y la carga de parásitos adultos. Para evaluar el efecto antihelmíntico in vitro sobre larvas infectantes de H. contortus susceptibles a todos los grupos químicos, se utilizó el test de inhibición de migración larval (IML) a 3 concentraciones diferentes (5 mg/ml, 15 mg/ml y 30 mg/ml). El efecto de los tratamientos fue analizado mediante un análisis de varianza y la estimación de las diferencias entre grupos se realizó por medio de la prueba LSD Fisher. Los resultados del test in vitro demostraron una reducción de la migración larval que varió entre el 74% y el 80%, a las concentraciones de entre 5 mg/ml y 30 mg/ml. Del análisis de varianza surgen diferencias significativas entre tratamientos (p = 0,0494). Al realizar la prueba de comparación de medias se evidenciaron diferencias significativas (p < 0,05) entre los promedios de migración a las diluciones de 5 mg/ml y 15 mg/ml, y de 5 mg/ml y 30 mg/ml, mientras que no se detectaron diferencias significativas entre la dilución de 15 mg/ml y 30 mg/ml. Estos resultados señalaron que el extracto de quebracho, a las diluciones evaluadas in vitro, presentó actividad antihelmíntica sobre larvas L3 susceptibles de H. contortus. Sin embargo, se requiere ampliar los estudios in vivo para demostrar un efecto antihelmíntico en ovinos.

ABSTRACT The objective of this work was to evaluate in vitro efficacy of the quebracho extract (Schinopsis spp.), rich in condensed tannins, against H. contortus in sheep, since there is evidence that this tanninsthese tannins can reduce egg excretion, fecundity of females and the burden of adult parasites. A larval migration inhibition (IML) test with 3 different concentration (5 mg/ml, 15 mg/ml, and 30 mg/ml) was used to evaluate the in vitro anthelmintic effect upon iInfective H. contortus larvae,from a susceptible strain to all chemical groupswere utilized with 3 diferentconcentration (5mg/ml, 15mg/ml, and 30mg/ml). The effect of the treatments was submitted to a variance analysis and the estimation of the differences between groups was evaluated using LSD Fisher test. Results from the in vitro test, revealed a reduction of the larval migration that varies from 74% to 80%, at the concentrations between 5 mg/ml to 30 mg/ml. From the analysis of variance, significant differences appear between treatments (p = 0,0494). After When performing the mean comparison test were performed, significant differences (p < 0,05) were found between the migration averages at dilutions of 5 mg/ml and 15 mg/ml, and between 5 mg/ml and 30 mg/ml, while were no't detected significant differences between the dilution of 15 mg/ml and 30 mg/ml. These results indicated that quebracho extract at the dilutions evaluated in vitro showed anthelmintic activity on L3 susceptible to H. contortus. However, it is necessary to conduct further studies in vivo to demonstrate an anthelmintic effect in sheep.

Anthelmintic efficacy of five tropical native Australian plants against Haemonchus contortus and Trichostrongylus colubriformis in experimentally infected goats (Capra hircus).

The study of the anthelmintic properties of plants rich in plant secondary metabolites can provide ecologically sound methods for the treatment of parasites on grazing animals. The purpose of the present study was to evaluate the anthelmintic effect of five tropical native Australian plant species rich in plant secondary metabolites on adult Haemonchus contortus and Trichostrongylus colubriformis in experimentally infected goats. Thirty young, nematode-free goats were infected with 2500 H. contortus and 5000 T. colubriformis infective larvae thrice weekly for a week (day 1-7 of the experiment). On day 27 after first infection, the goats were allocated into six groups of five animals per group. From day 28 to day 35, fresh leaves from Acacia salicina, Acacia nilotica, Eucalyptus corymbia, Casuarina cunninghamiana and Eucalyptus drepanophylla were included in the goats diet. Five groups were offered leaves from one of these plant species and one group, the untreated control, received only the basal diet formulated with 20% Medicago sativa and 80% Avena sativa. Following plant material administration, the goats were monitored daily until day 40 and then slaughtered on day 41. Total faecal worm egg output, total production of larvae recovered from faecal cultures, total post-mortem worm burdens and the per capita fecundity of female worms were estimated. The toxicity of the plant species for the goats was measured by histopathological analyses of liver and kidney samples. Results showed that goats feeding on the plant material rich in plant secondary metabolites had significantly lower egg output compared to the control goats (P<0.05). A similar response was found for larval production in both H. contortus and T. colubriformis supporting that egg output was affected in both species. Although the total worm burdens were not affected by the plant material (P>0.05), the per capita fecundity was significantly reduced by E. corymbia, A. nilotica and A. salicina (P<0.05). No signs of toxicity were detected in the liver or kidney samples. It is concluded that goats can benefit from the short-term ingestion of plant secondary metabolites, which reduce the total faecal egg output and thus decrease the potential for re-infection from the pasture.