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Master's Dissertation
DOI
https://doi.org/10.11606/D.64.2013.tde-18102013-100628
Document
Author
Full name
Edgard Franco Gomes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2013
Supervisor
Committee
Louvandini, Helder (President)
Amarante, Alessandro Francisco Talamini do
Hoste, Herve
Title in English
Inhibition of infective larvae exsheathment and egg hatching of the nematode Haemonchus contortus with extracts of tannin-rich plants
Keywords in English
Anthelmintic resistance
Ethnoveterinary
Haemonchus
In vitro
Parasitosis
Abstract in English
The aim of this work was to assess the bioactivity of extracts of the tannin-rich plants Acacia mearnsii, Myracrodruon urundeuva, Caesalpinea bracteosa and Leucaena leucocephala against egg and infective larvae stages of Haemonchus contortus. Two in vitro assays were held: an Egg Hatch Assay (EHA) and a Larval Exsheathment Inhibition Assay (LEIA). The EHA consists of the incubation of previously recovered eggs from infected animal's faeces in a solution of plant extract for 24 hours and later differentiation between larvae and nonhatched eggs. The concentrations used were 50.00, 25.00, 12.50, 6.25, 3.12, 1.56, 0.78 and 0.39 mg/mL for A. mearnsii; 1.56, 0.78, 0.39, 0.19, 0.09 and 0.04 mg/mL for M. urundeuva; 6.25, 3.12, 1.56, 0.78, 0.39 and 019 mg/mL for C. bracteosa; and 6.25, 3.12 and 1.56 mg/mL for L. leucocephala. The LEIA consists in the artificial exsheathment of infective larvae, obtained by previous coproculture, after a three hour incubation period with plant extract solution in the concentrations 1,200, 600, 300 and 150 'mü'g/mL. The 50 and 99 lethal doses (LD) were calculated for both tests. A dose-dependent effect was found in the two tests, except for L. leucocephala in EHA, where it was not possible to calculate DL50 and DL99 with the chosen doses. The DL50 results for EHA were 0.18, 0.32, and 7.20 mg/mL and for DL99 were 4.31, 5.41, and 187.26 mg/mL, respectively for M. urundeuva, C. bracteosa, and A. mearnsii. For LEIA, the DL50 were 0.40, 0.52, 1.24, and 2.24 mg/mL and for DL99 these were 2.37, 2.28, 19.99 and 2.53 x 103 mg/mL respectively for M. urundeuva, A. mearnsii, L. leucocephala and C. bracteosa. The two highest concentrations of A. mearnsii and the three highest for C. bracteosa were effective (more than 90% of bioactivity); the three highest concentrations of M. urundeuva and the 0.78 mg/mL level of C. bracteosa were moderately effective (between 80 and 90% of bioactivity); the concentrations with low effectiveness (between 60 and 80% of bioactivity) were the 12.50 mg/mL (A. mearnsii), 0.19 mg/mL (M. urundeuva), and 0.39 mg/mL (C. bracteosa); all other concentrations were ineffective (less than 60% of bioactivity). For the LEIA, only the highest dose from A. mearnsii and M. urundeuva were effective; the 600 'mü'g/mL were moderately effective and all other doses were ineffective. It should be observed that even if the dose is ineffective against exsheathment, some concentrations were able to significantly delay the process. It was observed that the extracts had bioactivity in vitro within the chosen doses against the hatchability of eggs and exsheathment of larvae of H. contortus, except for L. leucocephala, which was not able to block the hatching of eggs
Title in Portuguese
Inibições do desembainhamento de larvas infectantes e da eclodibilidade do nematoide Haemonchus contortus com extratos de plantas taniníferas
Keywords in Portuguese
Etnoveterinária
Haemonchus
In vitro.
Resistência anti-helmíntica
Verminose
Abstract in Portuguese
Objetivou-se com o presente trabalho verificar a bioatividade dos extratos das plantas taniníferas Acacia mearnsii, Myracrodruon urundeuva, Caesalpinea bracteosa e Leucaena leucocephala contra os estágios de ovo e de larva L3 infectante de Haemonchus contortus. Para isso, dois ensaios in vitro foram realizados: o Teste da inibição da eclodibilidade dos ovos (TIEO) e o teste da Inibição do desembainhamento larvar (TIDL). O TIEO consiste na incubação de ovos recém recuperados das fezes de animais infectados em solução liquida de extrato de planta por 24 horas e posterior diferenciação entre larvas e ovos não eclodidos. As concentrações utilizadas para A. mearnsii foram de 50,00, 25,00, 12,50, 6,25, 3,12, 1,56, 0,78 e 0,39 mg/mL; 1,56, 0,78, 0,39, 0,19, 0,09 e 0,04 mg/mL para M. urundeuva; 6,25, 3,12, 1,56, 0,78, 0,39 e 0,19 mg/mL para C. bracteosa; e 6,25, 3,12 e 1,56 mg/mL para L. leucocephala. O TIDL consiste no desembainhamento artificial de larvas infectantes, obtidas através de coprocultura, que passaram por período de incubação de três horas em solução liquida de extratos de plantas nas concentrações 1.200, 600, 300 e 150 'mü'g/mL. As doses letais (DL) 50 e 99 foram calculadas para ambos testes. Um efeito dose-dependente foi encontrado para os dois testes, exceto para a L. leucocephala no TIEO, onde não foi possível calcular o valor da DL50 e DL99 para o respectivo teste nas doses escolhidas. Os resultados da DL50 para TIEO foram de 0,18, 0,32 e 7,20 mg/mL e da DL99 foram de 4,31, 5,41 e 187,26 mg/mL respectivamente para M. urundeuva, C. bracteosa e A. mearnsii. Para o TIDL, a DL50 foi de 0,40, 0,52, 1,24 e 2,24 mg/mL e da DL99 foi de 2,37, 2,28, 19,99 e 2,53 x 103 mg/mL respectivamente para M. urundeuva, A. mearnsii, L. leucocephala e C. bracteosa. Para o TIEO, as duas maiores concentrações de A. mearnsii e as três maiores de C. bracteosa foram efetivas (mais de 90% de bioatividade); as três maiores concentrações de M. urundeuva e a 0,78 mg/mL de C. bracteosa foram moderadamente efetivas (entre 80 e 90% de bioatividade); as concentrações de pouca efetividade (entre 60 e 80% de bioatividade) foram a 12,50 mg/mL (A. mearnsii), 0,19 mg/mL (M. urundeuva), e 0,39 mg/mL (C. bracteosa); as demais concentrações foram consideradas ineficientes (menos de 60% de bioatividade). Para o TIDL, apenas a maior concentração de A. mearnsii e M. urundeuva foram efetivas; a concentração de 600 'mü'g/mL de M. urundeuva foi moderadamente efetiva; todas as outras concentrações foram ineficientes. Entretanto, deve-se observar que apesar de ineficientes em bloquear o desembainhamento, algumas concentrações atrasaram significativamente o desembainhamento das larvas, sendo esse um resultado de interesse. Assim, foi observado que os extratos, excetuando o extrato de L. leucocephala quanto a eclodibilidade, possuem bioatividade in vitro nas doses utilizadas contra a eclosão dos ovos e contra o desembainhamento das larvas de H. contortus
 
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Publishing Date
2013-10-25
 
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