35º Conbravet - Congresso Brasileiro de Medicina Veterinária

35º Conbravet - Congresso Brasileiro de Medicina Veterinária

ResumoID:05.726-1

AREA: Parasitologia

EFEITO IN VITRO DO EXTRATO DE ACÁCIA SOBRE LARVAS INFECTANTES DE TRICHOSTRONGYLUS COLUBRIFORMIS.

Minho A.p. (Instituto Agronômico do Pparaná); Filippsen L.a. (IAPAR); Amarante F.t.a (UNESP - Botucatu); Abdalla A.l. (CENA/USP)

Resumo

Introduction - The assay, which analyses the larval migration inhibition (LMI), uses infective larvae in presence of potential anthelmintic substances. Athanasiadou et al. (2001) Related that LMI and larvae feed inhibition are the best assay to test anthelmintic effect of bioactive compounds in vitro. Anthelmintic bioactivity against gastrointestinal nematodes has been associated with leguminous forages supporting the hypothesis of a role of condensed tannins. However, the possibility that other compounds might also been involved has received less consideration਍ഀ Objective - The main objective of this study is to determine the potential inhibitory effect of condensed tannins (CT) deriving of Acacia mearnsii extract (AE) on third stage larvae (L3) of Trichostrongylus colubriformis.਍ഀ Material and methods - The eggs were obtained from faeces collected from donor lambs carrying monoespecific infections of H. contortus. Strain isolated on IB – UNESP – Botucatu / SP was used. Coprocultures were carried out to isolate the L3, which were exsheathed and the solution adjusted so that 100ml contains approximately 100 larvae. Stock solution (200 mg mL-1) was made by dissolving the AE in distilled water. Eight serial dilutions of tannin extract (200 mg mL-1 to 35 mg mL-1) were made deriving it. All concentrations of AE and the distilled water control were tested in triplicate. Firstly, approximately, 100 larvae were dispense into a series of labelled eppendorf tubes and were added of 1 ml of the tested AE concentration. After centrifugation the supernatant were removed and the larvae resuspended using 1 ml of the same solution. This action was repeated three times, after this the L3 were incubated in the appropriate AE concentration, for 2 hours at 37°C. A test plate (24 well) was added to 1800µl AE solutions, including a filter in each used well. One sample of 200µl solution containing the larvae pre-incubated was added into each filter. After another 2-hour incubation at 37°C, the number of L3 that passed through the mesh and the restrained larvae in the filter were counted. To confirm the CT activity on L3 migration each assay were repeated in presence of PEG. The objective of using PEG is inactivating the most of CT effect proceeding from the AE. Ten micro liters of PEG solution were introduced in each eppendorf tube before the first L3 incubation.਍ഀ Results - The percentages (mean of triplicate) of L3 that have migrated through the mesh (viable larvae) are shown with and without the presence of PEG. The predicted value to reduce in 50 % the number of L3 that have migrated through the mesh (LD50) was, approximately, 40 mg.mL-1 (R2 = 0,902) and in presence of PEG the LD50 was 72 mg/mL (R2 = 0,977), showing the evidence of CT effect on infective larvae.਍ഀ Conclusion - The results suggest the deleterious effect of AE on L3 larvae of T. colubriformis affecting their motility during in vitro assays, but the CT is not the only bioactive compound.਍ഀ

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