A pesquisa teve como objetivo analisar o potencial antimicrobiano das nanopartículas de prata estabilizadas em curcumina e extrato de folhas de cajueiro (Anacardium occidentale L). Na metodologia as nanopartículas de prata (AgNPs) foram sintetizadas a partir de 125 mL de nitrato de prata (AgNO3) em ebulição sob agitação magnética e gotejamento de 5 mL de citrato de sódio 1%, e estabilizadas em curcumina e extrato de cajueiro. Os testes antimicrobianos foram realizados contra Staphylococcus aureaus, Escherichia coli, Candida albicans e Pseudomonas aeruginosa. O ensaio consistiu em dispersão do inóculo em toda a superfície das placas e posterior aplicação de discos contendo AgNPs na concentração de 1,0 mmol/L. Os halos formados foram mensurados com auxílio de um paquímetro em milímetros. Os resultados mostram que com as mudanças de coloração da solução na espectroscopia no ultravioleta visível UV-Vis, houve formação de AgNPs e indicaram atividade antimicrobiana contra cepas de Staphylococcus aureus. No entanto, não mostraram atividade inibitória contra a Pseudomonas aeruginosa e a Escherichia coli e também não apresentaram atividade inibitória de crescimento contra o fungo testado. Conclui-se que as AgNPs apresta potencial antimicrobiano contra Staphylococcus aureus. Portanto, devem ser testadas em outros microrganismos com outras concentrações, bem como ser aplicado em outras áreas tecnológicas e da saúde, como na regeneração tecidual.

Research background. Commercialization of Mauritia flexuosa (buriti) fruits in Brazil is at an early stage. Herein, we evaluate the nutritional value of pulp, peel and endocarp samples from buriti fruits, perform macroscopic and microscopic evaluations and analyze their physicochemical properties. Experimental approach. Size and mass, pH, sugar and protein contents, soluble/insoluble fiber, total titratable acidity and energy value of the samples were analyzed. Mineral profiling was performed by energy dispersive X-ray fluorescence spectrometry, and fatty acids and phytosterols were determined by gas chromatography-mass spectrometry. Samples were also submitted to differential scanning calorimetry coupled to a thermal analyzer, and microstructure, morphology, surface and viscosity were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) with copper radiation. Rheological behavior was also studied. Results and conclusions. Lyophilized pulp had higher nutritional content of minerals, proteins, carbohydrates and energy than in natura pulp. Lyophilized pulp and its by-products showed suitable yields (>17.31 %) and low aw, and potassium, manganese and monounsaturated fatty acid contents. Peels showed elevated amounts of saturated and polyunsaturated fatty acids and phytosterols (β-sitosterol and stigmasterol), and endothermic behavior. The reductions of calcium, magnesium and manganese ranging from 18.5 to 22.7 % were observed following the lyophilization. Drying processes generated semi-crystalline powders. Both peels and endocarp contained higher amounts of insoluble fiber and lower contents of sugars. Similar results were obtained by microscopic morphological analysis, differential scanning calorimetry and XRD analysis. Pulp and endocarp exhibited pseudoplastic non-Newtonian behavior, and flow behavior index values were lower than 1, while peels presented dilatant behavior. Thus, physicochemical and nutritional characterization of pulp and by-products, such as peels and endocarp, are essential to support scientific research and exploration of new sustainable products. Novelty and scientific contribution. Processing and conservation techniques, like lyophilization, maintain the good quality of nutritional contents and bioactive compounds of buriti whole fruits, and can be used to extend their shelf life, preserve alimentary characteristics and provide wider purposes and availability. Such parameters may generate income and food security for local and regional communities.

Introdução: As nanopartículas de prata apresentam cada vez mais relevância na prática médica. Ressalta-se que a síntese de nanopartículas de metal à base de plantas é uma abordagem emergente na síntese de nanopartículas. Objetivo: Desenvolver as nanopartículas de prata estabilizadas no extrato hidroalcóolico de Mentha Piperita L. para tratamento coadjuvante da depressão. Metodologia: Na síntese de nanopartículas em uma solução utilizou-se 25 mL de nitrato de prata (1,0 mmol/L) e 75 mL de Borohidreto de sódio (2,0 mmol/L). Essas duas substâncias foram misturadas a temperatura ambiente, sobre agitação magnética. Outra solução utilizou 100 mL de nitrato de prata (1,0 mmol/L) até alcançar a temperatura de ebulição e 5 mL de citrato de sódio (1%) foi adicionado sobre agitação magnética. O extrato seco hidroalcóolico de hortelã foi obtido a partir de folhas secas e álcool 70%. Resultados: As análises isoladas das soluções apresentaram picos de absorbância de 266 a 420 nm. Na mistura das soluções, notou-se que na presença de borohidreto de sódio os picos máximos de absorbância foram maiores. Conclusão: Para as duas soluções (com citrato/borohidreto) identificou-se a formação de nanopartícula de prata indicando que o extrato de hortelã é capaz de estabilizar a AgNps.

The incorporation of polymeric components into aerogels based on clay produces a significant improvement in the physical and thermal properties of the aerogels. In this study, clay-based aerogels were produced from a ball clay by incorporation of angico gum and sodium alginate using a simple, ecologically acceptable mixing method and freeze-drying. The compression test showed a low density of spongy material. In addition, both the compressive strength and the Young’s modulus of elasticity of the aerogels showed a progression associated to the decrease in pH. The microstructural characteristics of the aerogels were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The chemical structure was studied by infrared spectroscopy with Fourier transform (FTIR). The TGA curves from a non-oxidizing atmosphere indicated that the clay had a mass loss of 9% above 500 °C and that due to the presence of polysaccharides, the aerogels presented a decomposition of 20% at temperatures above 260 °C. The DSC curves of the aerogels demonstrated a displacement in higher temperatures. In conclusion, the results showed that aerogels of ball clay with the incorporation of polysaccharides, which are still minimally studied, have potential application as thermal insulation considering the mechanical and thermal results obtained.