RESUMO

Parasitism by gastrointestinal nematodes is a challenge for small ruminant farming worldwide. It causes productive and economic losses, especially due to parasite resistance to conventional anthelmintics. Natural compounds with antiparasitic activity are a potential alternative for controlling these parasites especially when considering the widespread occurrence of anthelmintic resistance. Our objective was to evaluate the activity of anacardic acid, geraniol, cinnamaldehyde and citronellal on Haemonchus contortus isolates with different levels of anthelmintic resistance profiles. These compounds were tested using egg hatch assays (EHAs), larval development tests (LDTs) as well as LDTs on mini-fecal cultures, on the Haemonchus contortus isolates Kokstad (KOK-resistant to all anthelmintics), Inbred-Strain-Edinburgh (ISE-susceptible to all anthelmintics) and Echevarria (ECH-susceptible to all anthelmintics). Effective concentrations to inhibit 50% (EC50) and 95% (EC95) of egg hatching and larval development were calculated. Results for EHA and LDT for all tested compounds, considering EC50 and EC95 values, showed low variation among the studied isolates with most RF values below 2x. All studied compounds showed efficacy against egg hatching and larval development of H. contortus isolates regardless of anthelmintic resistance profiles. The compounds with the smallest EC50 and EC95 values were cinnamaldehyde and anacardic acid making them promising candidates for future in vivo studies.(AU)

A infecção por nematoides gastrintestinais é um dos principais desafios na produção de pequenos ruminantes e ocasiona perdas produtivas, principalmente, devido à resistência anti-helmíntica. Bioativos com atividade anti-helmíntica são potencial alternativa para o controle desses parasitos em especial, considerando-se a ampla incidência de resistência anti-helmíntica nos rebanhos. O objetivo deste estudo foi avaliar a atividade biológica do ácido anacárdico, geraniol, cinamaldeído e citronelal em isolados de Haemonchus contortus com diferentes perfis de resistência anti-helmíntica. Foram realizados testes de eclosão de ovos (TEO), testes de desenvolvimento larvar (TDL) e TDLs em minicoproculturas, utilizando-se o isolado Kokstad (resistente a todos os anti-helmínticos), o isolado Inbred-Strain-Edinburgh (suscetível) e o isolado Echevarria (suscetível). Foram calculadas as concentrações efetivas para inibir 50% (CE50) e 95% (CE95) da eclodibilidade dos ovos e do desenvolvimento larvar. Resultados de TEO e TDL apresentaram baixa variação entre os diferentes isolados para um mesmo composto testado com fatores de resistência geralmente abaixo de 2x. Todos os compostos estudados mostraram eficácia contra a eclosão de ovos e desenvolvimento larvar de isolados de H. contortus independente do perfil de resistência anti-helmíntica dos mesmos. Os compostos que apresentaram atividade nas menores concentrações foram cinamaldeído e ácido anacárdico, sendo estes os componentes mais promissores para futuros estudos in vivo.(AU)

Assuntos

RESUMO

AIM OF THE STUDY: Anacardium occidentale Linn. (cashew) is a Brazilian plant that is usually consumed in natura and is used in folk medicine. Anacardic acids (AAs) in the cashew nut shell liquid are biologically active as gastroprotectors, inhibitors of the activity of various deleterious enzymes, antitumor agents and antioxidants. Yet, there are no reports of toxicity testing to guarantee their use in vivo models. MATERIALS AND METHODS: We evaluated AAs biosafety by measuring the acute, subacute and mutagenic effects of AAs administration in BALB/c mice. In acute tests, BALB/c mice received a single oral dose of 2000 mg/kg, whereas animals in subacute tests received 300, 600 and 1000 mg/kg for 30 days. Hematological, biochemical and histological analyses were performed in all animals. Mutagenicity was measured with the acute micronucleus test 24h after oral administration of 250 mg/kg AAs. RESULTS: Our results showed that the AAs acute minimum lethal dose in BALB/c mice is higher than 2000 mg/kg since this concentration did not produce any symptoms. In subacute tests, females which received the highest doses (600 or 1000 mg/kg) were more susceptible, which was seen by slightly decreased hematocrit and hemoglobin levels coupled with a moderate increase in urea. Anacardic acids did not produce any mutagenic effects. CONCLUSIONS: The data indicate that doses less than 300 mg/kg did not produce biochemical and hematological alterations in BALB/c mice. Additional studies must be conducted to investigate the pharmacological potential of this natural substance in order to ensure their safe use in vivo.

Assuntos

RESUMO

Aedes aegypti is the major vector of 1 of the most concerning arboviruses of the world, the dengue fever. The only effective way of reducing the incidence of dengue fever is to control the vector mosquito, mainly by application of insecticides to its breeding places. This study was aimed at assessing the insecticidal activity of sodium anacardate, isolated from Brazilian cashew nut shell liquid (CNSL), against the eggs, 3rd instars or pupae of Ae. aegypti. In addition, the acute toxicity of sodium anacardate to mice was also investigated. Sodium anacardate showed toxicity against Ae. aegypti eggs (median effective concentration [EC50] = 162.93 +/- 29.93 microg/ml), larvae (median lethal concentration [LC50] = 55.47 +/- 3.0 microg/ml) and pupae (LC50 = 369.78 - 52.30 microg/ml). On the other hand, even at high dose (0.3 g/kg body weight), this compound did not cause any adverse effects on mice, suggesting that this compound is safe to mammals. Therefore, sodium anacardate may be a viable low-cost alternative to help combat Ae. aegypti.

Assuntos