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The objective of this study was to evaluate the larvicidal activity of diterpenoids obtained from the oil-resin of Copaifera reticulata against Aedes aegypti larvae, the principal vector of dengue and urban yellow fever. Four diterpenes were obtained from oil-resin extraction with organic solvents and subsequent chromatographic and spectroscopic procedures allowed to isolation and identification of these compounds as 3-b-acetoxylabdan-8(17)-13-dien-15-oic acid (1), alepterolic acid (2), 3-b-hidroxylabdan-8(17)-en-15-oic acid (3), and ent-agatic acid (4). Each compound was previously dissolved in dimethylsulphoxide, and distilled water was added to obtain the desired concentrations. Twenty larvae of third instars were placed into plastic beckers, containing the solution test (25 mL), in a five repetitions scheme, and their mortality, indicated by torpor and darkening of the cephalic capsule, was recorded after 48h. Probit analyses were used to determine lethal concentrations (LC50 and LC90) and their respective 95% confidence intervals. This study showed that only diterpenoids 1 and 2 exhibited larvicidal properties with LC50 of 0.8 ppm and 87.3 ppm, respectively, revealing the former as the most toxic compound against third instars of Ae. aegypti. Therefore, this compound seems to be an interesting source for new metabolite to be exploited.O objetivo deste trabalho foi avaliar a atividade larvicida de diterpenos isolados do óleo-resina de Copaifera reticulata sobre Aedes aegypti, principal vetor de dengue e febre amarela urbana. Quatro diterpenóides foram obtidos a partir da extração do óleo-resina com solventes orgânicos e, subseqüentes procedimentos cromatográficos e espectroscópicos permitiram o isolamento e a identificação desses compostos como ácido 3-b-acetoxylabdan-8(17)-13-dien-15-óico (1), ácido alepterólico (2), ácido 3-b-hidroxylabdan-8(17)-en-15-óico (3) e ácido ent-agático (4). Cada um desses compostos foi previamente solubilizado em dimetilsulfóxido, acrescentando-se água, até se obterem as concentrações desejadas. Em cada bioensaio foram utilizadas 20 larvas de 3° estádio de Ae. aegypti colocadas em 25 mL da solução-teste. Foram feitas cinco repetições, e a mortalidade avaliada 48 h após a exposição, indicada pela ausência de movimentos e escurecimento da cápsula cefálica. Os dados obtidos da mortalidade x concentração (ppm) foram analisados, em gráfico de Probit para avaliar as concentrações letais (CL50 e CL90). Este estudo revelou que os diterpenóides 1 e 2 mostraram atividade larvicida com CL50 de 0,8 e 87,3 ppm, respectivamente, sendo o diterpeno 1 o composto mais promissor a ser usado como larvicida para o controle de Ae. aegypti.

p.25-28,v.50,n.1,São Paulo Jan./Feb.2008 Submitted by Rigaud Andréa (andrearigaud16@yahoo.com.br) on 2011-08-13T02:18:46Z No. of bitstreams: 1 a06v50n1.pdf: 63452 bytes, checksum: ef60f20e0824a8f8a8f458256dfa6946 (MD5) Made available in DSpace on 2011-08-13T02:18:46Z (GMT). No. of bitstreams: 1 a06v50n1.pdf: 63452 bytes, checksum: ef60f20e0824a8f8a8f458256dfa6946 (MD5) Previous issue date: 2008 The objective of this study was to evaluate the larvicidal activity of diterpenoids obtained from the oil-resin of Copaifera reticulata against Aedes aegypti larvae, the principal vector of dengue and urban yellow fever. Four diterpenes were obtained from oil-resin extraction with organic solvents and subsequent chromatographic and spectroscopic procedures allowed to isolation and identification of these compounds as 3-b-acetoxylabdan-8(17)-13-dien-15-oic acid (1), alepterolic acid (2), 3-b-hidroxylabdan-8(17)-en-15-oic acid (3), and ent-agatic acid (4). Each compound was previously dissolved in dimethylsulphoxide, and distilled water was added to obtain the desired concentrations. Twenty larvae of third instars were placed into plastic beckers, containing the solution test (25 mL), in a five repetitions scheme, and their mortality, indicated by torpor and darkening of the cephalic capsule, was recorded after 48h. Probit analyses were used to determine lethal concentrations (LC50 and LC90) and their respective 95% confidence intervals. This study showed that only diterpenoids 1 and 2 exhibited larvicidal properties with LC50 of 0.8 ppm and 87.3 ppm, respectively, revealing the former as the most toxic compound against third instars of Ae. aegypti. Therefore, this compound seems to be an interesting source for new metabolite to be exploited. São Paulo

Texto completo: acesso restrito. p. 341-345 Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-11-19T15:14:14Z No. of bitstreams: 1 10.1002-cbdv.200890032.pdf: 173390 bytes, checksum: f505ac1831a25bed627611f0646b80f5 (MD5) Made available in DSpace on 2013-11-19T15:14:14Z (GMT). No. of bitstreams: 1 10.1002-cbdv.200890032.pdf: 173390 bytes, checksum: f505ac1831a25bed627611f0646b80f5 (MD5) Previous issue date: 2008 The mosquito Aedes aegypti is an increasing problem of public health, being the vector responsible for dengue and Yellow Fever in tropical and subtropical regions. The aim of this work was to determine the potential larvicidal activity of a series of meroterpenoids, compounds 1–7, previously obtained fungal secondary metabolites from Penicillium sp., against the third-instar larvae of A. aegypti. The lethal concentrations (LC50 and LC90) of 1–7 were evaluated 24 h after exposure. Dehydroaustin (4) was the most active meroterpenoid in the series, with an LC50 value of 2.9 ppm, making it an attractive natural insecticide.

A dengue apresenta impacto na saúde pública das regiões intertropicais do mundo e tem como principal vetor o Aedes aegypti. As medidas mais usadas no controle desse vetor, até o momento, são os inseticidas sintéticos, que aplicados em larga escala durante longo período, fez aparecer resistência. Diante disso, compostos químicos provenientes de plantas podem ser substitutos dos inseticidas sintéticos, com as vantagens do retardamento da resistência, devido à complexidade de seus constituintes, da fácil degradação, da menor toxicidade ao homem e por ser uma alternativa mais segura para o meio ambiente. Ensaios com extrato bruto etanólico (ebe) da casca do caule de Persea americana foram realizados em copos de poliestireno, contendo soluções a 100 ppm do ebe de P. americana, previamente dissolvido em dimetilsulfóxido (DMSO) e água do sistema público de Goiânia. Em cada copo foram colocadas 5 larvas de 3° estádio (L3) do mosquito Aedes aegypti. O estudo das modificações morfohistológicas foi feito a partir de observações realizadas com 4, 8, 12, 16, 20, 24 e 48 h de tratamento com o ebe. Em cada período, as larvas foram coletadas, fixadas, desidratadas, infiltradas e incluídas em historesina. Foram realizados cortes de 3μm de espessura em micrótomo semiautomático, corados pela hematoxilina/eosina (HE), analisados e fotomicrografados em microscópio de luz. Para microscopia eletrônica de varredura (MEV) as larvas tratadas e controle foram fixadas, desidratadas, secas em aparelho de ponto crítico, metalizadas e analisadas em microscópio eletrônico. As modificações morfohistológicas foram observadas a partir de 24h após o tratamento das larvas L3 com ebe de casca de caule de P. americana. As análises dos cortes histológicos do mesêntero de larvas de Ae. aegypti, em microscopia de luz, mostraram a presença de vacúolos no citoplasma das células epiteliais, grande quantidade de secreção e dobramentos da membrana peritrófica nas larvas tratadas por 48h. Houve extrusão de todo conteúdo alimentar juntamente com a matriz peritrófica, sugerindo assim a ação tóxica de P. americana sobre o tubo digestivo das larvas. Essas modificações não ocorreram no grupo controle. Não houve evidência de alterações externas pelo MEV. Dengue has impact on public health of the intertropical regions of the world and its main vector Aedes aegypti. The measures most commonly used to control this vector, so far, are the synthetic insecticides, which applied on a large scale for a long period, did show resistance. Thus, chemical compounds from plants can be substitutes for synthetic insecticides, with the advantages of resistance retardation, due to the complexity of its components, easy degradation, lower toxicity to man and to be a safer alternative to the environment . Assays crude ethanol extract (cee) of Persea americana stem bark were performed in polystyrene cups, solutions containing 100 ppm of P. americana cee, previously dissolved in dimethylsulfoxide (DMSO) and water public Goiânia system. In each glass were placed 5 larvae of 3rd stage (L3) of the mosquito Aedes aegypti. The study was made of morfohistológic modifications from observations made with 4, 8, 12, 16, 20, 24 and 48 h treatment with the cee. In each period, the larvae were collected, fixed, dehydrated, infiltrated and embedded in historesin. of 3μm thick cuts were made in microtome semiautomatic, stained with hematoxylin / eosin (HE), analyzed and photomicrographed under a light microscope. For scanning electron microscopy (MEV) the treated and control larvae were fixed, dehydrated, dried in a critical point apparatus, metallized and analyzed in electron microscope. The morfohistológic changes were observed from 24 hours after treatment of larvae L3 with P. americana stem bark cee. The analysis of histological sections of the midgut of Ae. aegypti in light microscopy showed the presence of vacuoles in the cytoplasm of epithelial cells, large amount of secretion and folding of membrane peritrophic larvae treated for 48 hours. There was extrusion whole food content together with peritrophic matrix, thus suggesting the P.americana. toxic action on the gut of the larvae. These changes did not occur in the control group. There was no evidence of external changes by MEV.