In vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins towards acetone:water extracts of two tannin rich plants

Abstract

The aim of the study was to examine the variation in the in vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins using respective egg hatch assays (EHA) with acetone:water extracts of two tannin containing plants, chimay (Acacia pennatula) and sainfoin (Onobrychis viciifolia). Fresh eggs were incubated in PBS with different concentrations of each extract (0, 600, 1200, 2400, 3600, 5000 and 8000 μg/ml PBS). Additional concentrations were tested for O. viciifolia (75, 100, 200 and 400 μg/ml PBS). Effective concentrations 50% (EC50), with the corresponding 95% confidence interval (95% CI), were calculated for every isolate with both extracts. Moreover, a resistance ratio (RR) was calculated to compare the isolates, using the most susceptible isolate for each extract as the respective reference. A second set of incubations were made using polyvinylpolypyrrolidone (PVPP) (0, 5000 μg/ml, 5000 μg/ml+PVPP) to determine the influence of polyphenols on the AH effect. The proportion of morulated eggs, eggs with L1 larvae failing eclosion (%LFE), and emerged larvae were estimated at different extract concentrations. Data of each isolate was used to calculate the effective concentration 50% (EC50) for each extract. The EC50 of each isolate was used to determine resistance ratio (RR) for the different isolates. For the 2 extracts, a susceptibility variation in egg hatching was observed for the different H. contortus isolates. The EC50 values for A. pennatula ranged from 2203 to 14106 μg (RR from 2.01 to 6.40). The O. viciifolia extract showed higher variability with EC50 values ranging from 104 to 4783 μg (RR from 3.66 to 45.74). The main AH effects of the two extracts tested on the ten isolates consisted in blocking the emergence of L1 larvae (higher% LFE). Additional observations on emerged larvae showed that extract exposure caused alterations in the internal structure, separating the cuticle from the pharynx, bulb and intestinal cells. The use of PVPP revealed that (a) condensed tannins were not the sole plant secondary metabolites responsible for the AH effects, and (b) different H. contortus isolates showed variability in the role of tannins either on the ovicidal effect or the %LFE.

Anthelmintic activity of Cratyliamollis leaves against gastrointestinal nematodes in goats

“…(personal communication), some phenolic compounds were determined in the leaf extract, such as flavonoids, flavans, norsesquiterpene and coumarins, beyond two steroids (megastimanes and ergostane) (LIMA et al, 2009). So, the effects resulting from this treatment could be explained by the presence of phenolic compounds in C. mollis leaf decoction extract, especially tannins that can affect the nematode fecundity, once several studies support the role of these compounds as antiparasitic agents (MOLAN et al, 2003;CHAN-PÉREZ et al, 2016). However, this activity may also be related to the presence of megastimanes and ergostane steroids, considering that steroidal saponins have been reported to have anthelmintic activity (ATHANASIADOU et al, 2001;DOMINGUES et al, 2010).…”

“…In accordance with other studies, the mechanisms by which an extract can inhibit the microbial growth are varied and can be due in part to the hydrophobic nature of some of its components. These molecules can interact with the lipid bilayer of the cell membrane and affect the respiratory chain and the production of energy, leading to the interruption of intracellular signalling cascades vital for cellular functions (LEWANDOWSKA et al, 2013;CHAN-PÉREZ et al, 2016), which can affect various targets, where the different therapeutic components collaborate in a synergistic effect, having greater anthelmintic activity than the purified individual constituent (CORNARA et al, 2016). Relative to the humoral immune response, a significant rise in the total IgA was observed in the animal treated with the extract, whereas IgG level remained low in the same group when compared to control groups.…”

Susceptibility of ten Haemonchus contortus isolates from different geographical origins towards acetone:water extracts of polyphenol-rich plants. Part 2: Infective L3 larvae

“…The latter allowed the identify differences in susceptibility for different H. contortus isolates and even different life stages. For instance Annonacea leaf extracts (Castañeda Ramírez et al, 2014), and acetone:water extracts from different tropical tree leaves and by products (Vargas Magaña et al, 2014a;Chan Pérez et al, 2016, Ortíz Ocampo et al, 2016Vargas Magaña et al, 2014aVar gas Magaña et al, 2014aChan Pérez et al, 2016, Ortíz Ocampo et al, 2016Vargas Magaña et al, 2014aVargas Magaña et al, 2014aChan Pérez et al, 2016, Ortíz Ocampo et al, 2016.…”

“…The acetone:water extract produced with Onobrychis viciifolia foliage was produced at the Unité Mixte de Recherche Interactions Hôtes Agents Pathogènes (UMR/IHAP) of Institut National de la Recherche Agronomique/École Nationale Vétérinaire de Toulouse (INRA/ENVT), France. These extracts were previously used to explore the in vitro variation of susceptibility of H. contortus eggs towards the two tannin rich extracts (Chan Pérez et al, 2016). The extraction procedure was performed as follows: fresh leaves of the two plants were collected to obtain acetone:water extracts.…”

Plants and their medicinal potential for controling gastrointestinal nematodes in ruminants

“…and Onobrychis viciifolia (Scop. ), although this difference in sensitivity was not related to geographic region [77] , since strains from nearby regions behaved differently when exposed to these polyphenols. Therefore, it is not possible to relate the collection area of a plant rich in tannins with its activity on parasite strains from distant areas, demystifying the idea that a sample of tannin or other metabolite from a tropical area should be more active against parasites from temperate areas, for example.…”