Water extracts of Brazilian leguminous seeds as rich sources of larvicidal compounds against Aedes aegypti L.

This study assessed the toxicity of seed water extracts of 15 leguminous species upon Aedes aegypti larvae. A partial chemical and biochemical characterization of water extracts, as well as the assessment of their acute toxicity in mice, were performed. The extracts of Amburana cearensis, Anadenanthera macrocarpa, Dioclea megacarpa, Enterolobium contortisiliquum and Piptadenia moniliformis caused 100% of mortalit y after 1 to 3 h of exposure. They showed LC50 and LC90 values ranging from 0.43 ± 0.01 to 9.06 ± 0.12 mg/mL and from 0.71 ± 0.02 to 13.03 ± 0.15 mg/mL, respectively. Among the secondary metabolite constituents, the seed water extracts showed tannins, phenols, flavones, favonols, xanthones, saponins and alkaloids. The extracts also showed high soluble proteins content (0.98 to 7.71 mg/mL), lectin (32 to 256 HU/mL) and trypsin inhibitory activity (3.64 = 0.43 to 26.19 = 0.05 gIT/kg of flour) The electrophoretic profiles showed a great diversity of protein bands, many of which already described as insecticide proteins. The extracts showed low toxicity to mice (LD50 > 0.15 = 0.01 g/kg body weight), but despite these promising results, further studies are necessary to understand the toxicity of these extracts and their constituentsfrom primary and secondary metabolism upon Ae. aegypti.<br>Este trabalho objetivou avaliar a toxicidade dos extratos aquosos de sementes de 15 espécies de leguminosas contra larvas de Aedes aegypti. Foi realizada uma caracterização química e bioquímica parcial dos extratos aquosos e a avaliação da toxicidade aguda em camundongos. Os extratos de Amburana cearensis, Anadenanthera macrocarpa, Dioclea megacarpa, Enterolobium contortisiliquum e Piptadenia moniliformis causaram 100% de mortalidade depois de 1 a 3 h de exposição e mostraram valores de CL50 e CL90 entre 0,43 = 0,01 e 9,06 ± 0,12 e entre 0,71 = 0,02 e 13,03 = 0,15 mg/mL, respectivamente. Dentre os constituintes do metabolismo secundário, os extratos das sementes apresentaram taninos, fenóis, flavonas, flavonóis, xantonas, saponinas e alcalóides. Os extratos apresentaram alto teor de proteínas solúveis (0,98 to 7,71 mg/mL), lectina (32 to 256 UH/mL) e inibidor de tripsina (3,64 ± 0,43 to 26,19 = 0,05 gIT/kg de farinha). O perfil eletroforéticomostrou uma grande diversidade de proteínas, muitas dasquais já descritas como inseticidas. Os extratos mostraram baixa toxicidade ao camundongo (DL50 > 0,15 = 0,01 g/kg peso corporal), porém apesar desses resultados promissores, estudos posteriores são necessários para compreender a toxicidade desses extratos e de seus constituintes do metabolismo primário e secundário sobre Ae. aegypti

Essential Oils from Aromatic and Medicinal Plants as Effective Weapons Against Mosquito Vectors of Public Health Importance

The fight against mosquito-borne diseases has recently seen the failure of control programmes based on synthetic chemical treatments to combat larvae and adults of mosquito vectors. This has led to several problems linked to residual substances causing a detrimental impact on environment and human health and to the development of resistance in mosquitoes. In this scenario, new eco-friendly and alternative strategies for the management of mosquito-borne diseases come from the use of plant essential oils (EOs). These are complex mixtures of small, volatile and lipophilic compounds, mostly belonging to monoterpenoids, sesquiterpenoids and phenylpropanoids, produced by aromatic plants belonging to several botanical families such as Apiaceae, Asteraceae, Geraniaceae, Lamiaceae, Lauraceae, Myrtaceae, Poaceae, Rutaceae, Verbenaceae and Zingiberaceae. An important ecological role played by EOs is defending plants from several enemies such as bacterial and fungal pathogens, viruses, insects and parasites. EOs represent ideal candidate ingredients to be incorporated in insecticidal formulations since scientific evidences have documented their efficacy against larvae and adults of several mosquitoes (e.g. Anopheles, Aedes and Culex) even at low doses (&lt;50 ppm), the multiple mode of action and wide spectrum of efficacy, the low toxicity on nontarget organisms and environment and the unlikely capacity to induce insect resistance. In this chapter, we gave an overview of the most important EOs obtained from commercially important botanical families with documented efficacy against mosquito vectors. Particular attention has been paid to highlight their strengths and weakness and the future challenges leading to the replacement of conventional insecticides by agrochemical companies