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

Abstract

This study explored the variation in susceptibility to acetone:water plant extracts between infective larvae (L) of ten Haemonchus contortus isolates from different geographical origin. The L of 10 different isolates were exposed either to the acetone:water extract of a temperate plant (Onobrychis viciifolia) or a tropical plant (Acacia pennatula) and were evaluated with the larval exsheathment inhibition assay (LEIA). The L of each isolate were incubated with different concentrations of each extract (0, 25, 50, 100, 200, 400, 600, 800, 1000 and 1200μg/mL of phosphate buffered saline (PBS)). After incubation, the exsheathment process of L was induced using a solution with sodium hypochlorite (2%) and sodium chloride (16.5%). The proportion of exsheathed L was determined for each concentration at 0, 20, 40 and 60min. Effective concentrations 50% (EC) and the corresponding 95% confidence intervals (95% CI) were calculated for every isolate with both extracts. Moreover, a resistance ratio (RR) was calculated for each extract to compare isolates, using the most susceptible isolate as the respective reference for each extract. To determine the role of polyphenols on the reported effect, a second set of incubations was made for each isolate and each extract, using the extracts at a concentration of 1200μg/mL PBS with or without polyvinylpolypyrrolidone (PVPP), a polyphenol blocking agent, and controls without extract. The ten different H. contortus isolates showed variation in susceptibility for each of the 2 extracts tested (P<0.05). The EC values for A. pennatula extract ranged from 36 to 501μg/mL (RR: 2.11-13.68). Meanwhile, the EC values for O. viciifolia extract ranged from 128 to 1003μg/mL (RR: 1.25-7.82). The use of PVPP revealed that polyphenols were responsible for the anthelmintic activity recorded for both extracts. However, tested H. contortus isolates suggested that susceptibility to one polyphenol-rich extract did not determine the susceptibility to the other polyphenol rich extract. The latter result indicated that the different H. contortus isolates varied in their susceptibility to the polyphenols present in each extract evaluated.

In Vitro Anthelmintic Activity of Methanolic Extract from Caesalpinia coriaria J. Willd Fruits against Haemonchus contortus Eggs and Infective Larvae

“…Olmedo-Juárez et al [5] reported a larvicidal effect ( H. contortus ) greater than 70% at a dose of 150 mg/mL with an extract made from Acacia cochliacantha leaves and an LC 50 and LC 90 of 127.3 and 177.8 mg/mL, respectively. Also Chan-Pérez et al [14, 15] observed that H. contortus larvae after being exposed to an acetonic: aqueous extract of A. pennatula and O. viciifolia at concentrations of 600 μ g/mL showed evident lesions such as separation of the cuticle and the internal structures including the pharynx, bulb, and intestinal cells and when they were exposed to doses of 5000 μ g/mL the cuticle of the larvae was clearly swollen and the internal structures (pharynx, bulb, and intestine) were not distinguishable. The results also show that the larvicidal activity of the extract depends directly on the concentration dose.…”

Use of agro-industrial by-products containing tannins for the integrated control of gastrointestinal nematodes in ruminants

“…A similar approach has been proposed for tropical regions. However, this search has also been prompted by a recent discovery: an H. contortus isolate from Mexico showing lower susceptibility to polyphenol-rich acetone: water extracts produced from leaves of plants commonly ingested by local sheep or goats [16,21,115]. These authors proposed that the H. contortus isolates obtained from animals browsing the tropical forest of Mexico showed some level of adaptation to plant polyphenols, possibly due to the constant exposure of the local GIN to the polyphenol-rich vegetation consumed by the hosts browsing this area.…”

Variabilidad en el contenido de polifenoles, actividad biológica y antihelmíntica de extractos metanol:agua de las hojas de Gymnopodium floribundum Rolfe

“…El porcentaje del desenvaine (%D) y el de inhibición del desenvaine (%IDL) se determinaron con las siguientes fórmulas (28) : %D = Larvas L 3 con vaina larvas con vaina + larvas sin vaina × 100 %IDL = 100 − %D La inhibición de la EH y los resultados de IDL obtenidos para los diferentes extractos se analizaron con los respectivos modelos lineares generalizados (MLG) para evaluar las diferencias entre el control PBS y las diferentes concentraciones de extracto analizados. Los datos obtenidos de las incubaciones de PVPP de cada extracto se analizaron usando un diseño completamente al azar (MLG con comparaciones realizadas con el grupo control respectivo para cada extracto) (26) .…”