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Resumen Introducción: Análogos del alcaloide girgensohnina, diseñados y sintetizados para inhibir a la enzima acetilcolinesterasa, han presentado efecto insecticida sobre insectos vectores de enfermedades. Objetivo: Determinar la actividad insecticida de 12 análogos sintéticos de gingersohnina sobre ninfas del primer estadio de Triatoma dimidiata. Materiales y Métodos: Se tomó como referencia el protocolo de la OMS 2005. Ninfas del primer estadio de T. dimidiata fueron expuestas a los análogos por aplicación tópica y exposición a superficies para determinar las dosis letales (DL50 y DL95) y verificar alteración en la locomoción mediante el software Videomex V. Resultados: El análogo 6 presentó la mayor actividad insecticida a las 72h con una mortalidad del 20,8% ± 3,57 para el tratamiento de topicación 25% ± 0,00 para las superficies no porosas. Las dosis letales de la molécula 6 fueron: DL50 1036,8 ± 0,38 ng/insecto y DL95 3991,4 ± 0,50 ng/insecto respectivamente. Con respecto a la locomoción, el análogo indujo un comportamiento similar al insecticida comercial deltametrina.
Abstract Introduction: Analogs of the girgensohnine alkaloid, designed and synthesized to inhibit acetylcholinesterase enzyme, have presented an insecticidal effect on vectors insects of diseases. Objective: To determine the insecticidal activity of 12 synthetic analogs of gingersohnine in first stage nymphs of Triatoma dimidiata. Materials and methods: WHO protocol 2005, using exploratory doses, was used to determine the best molecule according to its mortality. First stage nymphs of T. dimidiata were exposed to different doses of the analogs by topical application and surface exposure. Lethal doses (LD50 and DL95) and alterations in locomotion using Videomex V software were determined. Results: Analog 6 presented the highest insecticidal activity at 72 h with a mortality of 20.8% ± 3.57 for topical treatment and 25%±0,0 for non-porous surfaces evaluation. Analog 6 lethal doses were LD50 1036.8 ± 0.38 ng/insecto and DL95 3991.4 ± 0.508 ng/insecto, respectively. With regard to locomotion, analogue 6 induced a similar behavior to that observed for commercial insecticide deltametrin.
Subject(s)
Humans , Chagas Disease , Triatoma , ToxicityABSTRACT
Abstract Aedes aegypti is the principal vector of arboviral pathogens that may cause diseases as dengue fever, chikungunya and zika. The harmful environmental effects of commercial pesticides coalesced with the development of insecticide-resistant populations encourage the discovery and generation of new alternative products as a tool to reduce the incidence of vector-borne diseases. In this work, through the classic three component Strecker reaction of commercial benzaldehydes, cyclic secondary amines and KCN, a new series of nine α-amino nitriles, girgensohnine analogs, has been synthetized and screened for larvicide and adulticide properties against A. aegypti, one of the dominant vectors of dengue, chikungunya and zika in tropical and subtropical areas all over the world. Molecules 3 and 4 were identified as potential larvicidal agents with LC50 values of 50.55 and 69.59 ppm, respectively. Molecule 3 showed 100% of mortality after 2 h of treatment when a concentration of 30 ppm in adulticidal assays was evaluated. Additionally, in order to elucidate the mode of action of these molecules, their acetylcholinesterase (AChE) inhibitory properties were evaluated using the Ellman assay. It was found that the molecules possess a weak AChE inhibitory activity with IC50 values between 148.80 and 259.40 µM, indicating that AChE could not be a principal target for insecticide activity.
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Abstract The search for new insecticides to control dengue fever, chikungunya, and Zika vectors has gained relevance in the past decades. The aim of the present study was to evaluate the larvicidal action of essential oils (EOs) from Thymus vulgaris, Salvia officinalis, Lippia origanoides, Eucalyptus globulus, Cymbopogon nardus, Cymbopogon martinii, Lippia alba, Pelargonium graveolens, Turnera diffusa, and Swinglea glutinosa on Aedes (Stegomyia) aegypti. The EOs were extracted by microwave-assisted hydrodistillation and characterized by gas chromatography/mass spectrometry (GC/MS). The chemical components of the EOs were identified by linear retention indices and mass spectra. Lethal concentrations (LC50 and LC95) were determined by probit analysis using larvae of Ae. aegypti between the third and the fourth instars. All EOs achieved larvicidal activity at LC50 values lower than 115 mg/L. The lowest LC50 value (45.73 mg/L) corresponded to T. vulgaris EO, whereas C. martinii EO showed the highest LC50 (LC50 = 114.65 mg/L). Some EO mixtures showed lower LC50 than oils used individually, such as the mixtures of L. origanoides + S. glutinosa (LC50 = 38.40 mg/L), T. diffusa + S. glutinosa (LC50 = 63.71 mg/L), and L. alba + S. glutinosa (LC50 = 48.87 mg/L). The main compounds of the EOs with highest larvicidal activity were thymol (42%) and p-cymene (26.4%).
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ABSTRACT Introduction: The alkaloid girgensohnine has been used as a natural model in the synthesis of new alkaloid-like alpha-aminonitriles with insecticidal effect against disease vectors. Objective: To evaluate the biocide activity of girgensohnine analogues and essential oils of Cymbopogon flexuosus, Citrus sinensis and Eucalyptus citriodora in stage I and stage V Rhodnius prolixus nymphs. Materials and methods: We used a topical application model in tergites and sternites, as well as exposure to treated surfaces with different exploratory doses of each of the molecules and essential oils to determine the lethal doses (LD50 and LD95). Results: Analogue 3 showed the highest insecticidal activity with 83.3±16.7% of mortality when applied on tergites, 38.9±4.8% on sternites and 16.7±0% on treated surfaces in stage I nymphs at 72 hours (h) and 500 mg.L-1. In stage V nymphs, the compounds induced mortality only in sternums (11.1±9.6% for analogue 6 and 5.5±4.7% for analogues 3 and 7 at 72 h and 1500 mg.L-1). The lethal doses for molecule 3 on tergites in stage I nymphs were LD50 225.60 mg.L-1 and LD95 955.90 mg.L-1. The insecticidal effect of essential oils was observed only in stage I nymphs, with 11.1±4.8% for C. flexuosus when applied in sternites, while using exposure to surfaces treated it was 5.6±4.8% for C. sinensis applied on tergites and 8.3±0% on sternites at 72 h and 1000 mg.L-1. Conclusion: Synthetic girgensohnine analogues, and C. flexuosus and C. sinensis essential oils showed insecticidal activity in R. prolixus. Analogue 3 showed the greatest insecticidal activity among all molecules and oils evaluated under our laboratory conditions.
RESUMEN Introducción. El alcaloide natural girgensohnina se ha usado como modelo en la síntesis de nuevos análogos de alcaloidales alfa-aminonitrílicos con efecto insecticida en vectores de enfermedades. Objetivo. Evaluar la actividad biocida de análogos de girgensohnina y de aceites esenciales de las plantas Cymbopogon flexuosus, Citrus sinensis y Eucalyptus citriodora en ninfas de estadios I y V de Rhodnius prolixus. Materiales y métodos. Se empleó la aplicación tópica en terguitos, esternitos y superficies tratadas con diferentes dosis exploratorias de cada una de las moléculas y aceites esenciales para determinar las dosis letales (LD50 y LD95). Resultados. El análogo 3 tuvo la mayor actividad insecticida, con una mortalidad de 83,3±16,7% en los terguitos, de 38,9±4,8 % en los esternitos y de 16,7±0 % a las 72 horas en ninfas de estadioI expuestas a superficies tratadas y 500 mg.L-1. En las ninfas de estadio V solo se presentó mortalidad en los esternitos (11,1±9,6 % con el análogo 6 y 5,5±4,7 % con los análogos 3 y 7 a las 72 h y 1.500 mg.L-1). Las dosis letales para la molécula 3 en los terguitos de ninfas de estadio I fueron las siguientes: DL50, 225,60 mg.L-1 y DL95, 955,90 mg.L-1. En cuanto a los aceites esenciales, el efecto insecticida solo se presentó con C. flexuosus (11,1±4,8%) en los esternitos de ninfas de estadio I expuestas a superficies tratadas; con C. sinensis (5,6±4,8%) en los terguitos y en los esternitos (8,3±0%) a las 72 horas y 1.000 mg.L-1. Conclusión. Los análogos sintéticos del alcaloide girgensohnina y los aceites esenciales de C. flexuosus y C. sinensis exhibieron actividad insecticida en R. prolixus. El análogo 3 exhibió la mayor actividad insecticida de todas las moléculas evaluadas bajo las condiciones de laboratorio.
Subject(s)
Animals , Pyrrolidines/pharmacology , Rhodnius , Oils, Volatile/pharmacology , Insecticides , Nitriles/pharmacology , Pyrrolidines/administration & dosage , Pyrrolidines/chemical synthesis , Rhodnius/growth & development , Plant Oils/pharmacology , Oils, Volatile/administration & dosage , Molecular Structure , Administration, Topical , Cymbopogon/chemistry , Citrus sinensis/chemistry , Eucalyptus/chemistry , Hydrophobic and Hydrophilic Interactions , Eucalyptus Oil/pharmacology , Insecticides/administration & dosage , Insecticides/chemical synthesis , Lethal Dose 50 , Nitriles/administration & dosage , Nitriles/chemical synthesis , NymphABSTRACT
Avaliou-se a abundância e agregação dos ovos de Aedes aegypti L. e Aedes albopictus Skuse em Cambé, Ibiporã, Jacarezinho, Maringá e Paranavaí, PR, utilizando-se armadilhas de oviposição. De 225 armadilhas instaladas, 100 registraram-se positivas para ovos. Coletaram-se 4140 ovos, demonstrando distribuição altamente agregada. Ambas as espécies foram encontradas em Cambé, Jacarezinho, Maringá e Paranavaí. Ae. albopictus não foi detectado em Ibiporã, porém onde esteve presente foi menos abundante. A relação entre sexos aproximou-se de 1:1, para Ae. aegypti. Na comparação dos números de adultos coletados entre as duas espécies, obteve-se correlação negativa nas amostras de Maringá e Cambé, o que foi atribuído à sazonalidade dessas populações. A coexistência dessas espécies indica que elas estão sobre pressão dos programas de controle, sendo, portanto necessárias avaliações específicas.
The abundance and aggregation of eggs of Aedes aegypti L. and Aedes albopictus Skuse was evaluated in the municipalities of Cambé, Ibiporã, Jacarezinho, Maringá and Paranavaí, in the State of Paraná, Brazil by means of oviposition traps. Of the 225 installed traps, 100 were registered as positive for eggs; 4140 eggs were collected, thus demonstrating an highly aggregate distribution. Both species were registered in Cambé, Jacarezinho, Maringá and Paranavaí. Ae. albopictus was generally less abundant and was not present in Ibiporã nor in the oviposition traps of a second collection of Maringá. The relation between sexes for Ae. aegypti was approximately 1:1. In the comparison of the number of adults collected between the two species, a negative correlation was obtained in the samples of Maringá and Cambé, what was attributed the seasonality of these populations. The coexistence of these species indicates that both are under pressure by the control programs, therefore specific evaluations are necessary.