RESUMO:Tendo em vista que bactérias resistentes a antimicrobianos representam um desafi o no tratamento de infecções, é notória a necessidade de encontrar novas substâncias com propriedades antimicrobianas para serem utilizadas no combate a esses microrganismos. Este trabalho relata a avaliação da atividade antibacteriana, toxicidade e identifi cação dos componentes químicos do óleo essencial de Croton zehntneri (variedade estragol), planta utilizada na medicina popular como calmante e estimulante do apetite. A atividade antimicrobiana e a concentração inibitória mínima (CIM) foram determinadas pelo método de difusão em discos. A avaliação da toxicidade foi realizada frente à Artemia salina com resultado considerado ativo (CL 50 < 100 μg/mL). O óleo essencial das folhas apresentou atividade antibacteriana frente a todas as bactérias testadas exceto contra Salmonella typhimurium, sendo o melhor resultado frente a Shigella fl exneri com CIM de 50 μg/mL. A análise da composição química foi obtida por cromatografi a gasosa acoplada a espectrometria de massa (CG/EM) e permitiu identifi car um total de 97,4% dos componentes, com presença majoritária de estragol (76,8%). A presença de tal constituinte nos impulsiona a realização de estudos com outras bactérias, já que o estragol foi anteriormente relatado como sendo responsável por atividades antibacterianas. Unitermos:Croton zehntneri, Euphorbiaceae, estragol, óleo essencial, atividade antibacteriana, toxicidade, CIM.ABSTRACT: "Chemical composition and evaluation of the antibacterial activity and toxicity of the essential oil of Croton zehntneri (variety estragol)". Observing that bacteria resistant to antimicrobials represent a challenge in the treatment of infections, it is notorious the need of fi nding new substances with antimicrobial features to be used in the fi ght against these microorganisms. This work relates the evaluation of the antibacterial activity, toxicity and identifi cation of the chemical components of the essential oil of Croton zehntneri (variety estragol), plant used in the popular medicine as tranquilizer and appetite stimulant. The antimicrobial activity and minimum inhibitory concentration (MIC) were determined by the method of diffusion in discs. The evaluation of the toxicity was held through brine shrimp test with results considered active (LC 50 < 100 μg/mL). The essential oil of leaves presented antibacterial activity with all the bacteria tested except with Salmonlla typhimurium, being the best result with the Shigella fl exneri with MIC of 50 μg/mL. The analysis of the chemical composition was obtained by gas chromatography coupled to mass spectrometry (GC/MS) and permitted to identify a total of 97.4 % of the components, with major presence of estragol (76.8%). The presence of the latter drives us to studies with other bacteria, as the estragol was previously reported as being responsible for antibacterial activities.

Background The Aedes aegypti mosquito is the primary vector for several diseases. Its control requires a better understanding of the mosquitoes’ live cycle, including the spatial dynamics. Several models address this issue. However, they rely on many hard to measure parameters. This work presents a model describing the spatial population dynamics of Aedes aegypti mosquitoes using partial differential equations (PDEs) relying on a few parameters. Methods We show how to estimate model parameter values from the experimental data found in the literature using concepts from dynamical systems, genetic algorithm optimization and partial differential equations. We show that our model reproduces some analytical formulas relating the carrying capacity coefficient to experimentally measurable quantities as the maximum number of mobile female mosquitoes, the maximum number of eggs, or the maximum number of larvae. As an application of the presented methodology, we replicate one field experiment numerically and investigate the effect of different frequencies in the insecticide application in the urban environment. Results The numerical results suggest that the insecticide application has a limited impact on the mosquitoes population and that the optimal application frequency is close to one week. Conclusions Models based on partial differential equations provide an efficient tool for simulating mosquitoes’ spatial population dynamics. The reduced model can reproduce such dynamics on a sufficiently large scale.

No abstract