Neusa Fernandes de Moura

Miniprojeto para ensino de Química Orgânica Experimental baseado no acoplamento catalítico N-C promovido por micro-ondas

This paper describes a three-week mini-project for an Experimental Organic Chemistry course. The activities include N-C cross-coupling synthesis of N-(4-methoxyphenyl) benzamide in an adapted microwave oven by a copper catalyst (CuI). Abilities and concepts normally present in practical organic chemistry courses are covered: use of balances, volumetric glassware, separation of mixtures (liquid-liquid extraction and filtration), chromatographic techniques, melting point determination and stoichiometric calculations.

Development of a quantitative approach using Raman spectroscopy for carotenoids determination in processed sweet potato

The orange-fleshed sweet potato is a vegetable-rich in carotenoids. The thermic treatment for sweet potato processing can decrease the content of these constituents in the foods, lowering their bioactive properties. Raman spectroscopy has been growing as a fast tool to food analysis, especially for detection of low concentrations of carotenoids and to the monitoring of its degradation profile over time. Therefore, in this work were evaluated two methods of drying, hot air and microwaving with rotary drum, combined with quantitative Raman spectroscopy. The results showed carotenoids degradation around 50% for both types of drying processes studied. PCA plot proved the potential of reproducibility of analyses for microwave drying samples. For samples heated with hot air, the best linear correlation achieved was R2u202f=u202f0.90 and by microwave was R2u202f=u202f0.88. Also, partial least squares (PLS) regression models were constructed obtaining a satisfactory coefficient of determination.

Planejamento experimental do processo de secagem da amora-preta (Rubus sp.) para a produção de farinha enriquecida com compostos bioativos

The blackberry drying process was studied using an experimental design with three factors, namely: sample weight (6 to 135 g), drying temperature (30 to 80 °C) and time (16 to 24 h). All samples were grounded and dried accordingly, in a convection oven with air circulation. Moisture and phenolic compounds concentration were chosen as response variables. Results showed small losses of bioactive compounds for the 80 g sample dried at 55 °C for 16 hours. Furthermore, the blackberry flour meets the Brazilian standards to moisture (maximum 15%) and can be classified as a product of high fiber content (24.33±2.88 g/100 g of flour). Bioactive compounds in the flour were quantified using spectrophotometric analysis: total phenolic of 344.94 mg GAE/100 g; total flavonoids of 182.82 Ce mg/100 g; total anthocyanins of 77.93 mg/100 g; monomeric anthocyanins of 82.41 CYD-3-G/100 g; total carotenoids of 0.322 mg/100 g and activity anti-DPPH EC50 21.2 μg/mL. These results show that blackberry flour is rich in bioactive compounds, adding nutritional value to foods and products made with this flour.

Chemical composition and multivariate analysis of the volatile oil of Dalbergia frutescens (Vell.) Britton (Fabaceae)

The chemical composition of the volatile oil from the leaves of three specimens of D. frutescens, collected over a period of one year, was determined by gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame ionization detection (GC-FID). These essential oils were characterized by the presence of norisoprenoids (β-damascenone, β-ionone, and α-ionone), as well as sesquiterpenes. Multivariate analysis showed that the compounds β-damascenone and β-ionone exerted the greatest influence on spatial and temporal differences in the composition of the oils. Samples obtained from specimens located in the same city showed similar chemical compositions.

Efeitos das condições ambientais sobre o teor e variabilidade dos óleos voláteis de dalbergia frutescens (Vell.) Britton (Fabaceae)

The volatile oils of Dalbergia frutescens were obtained by hydrodistillation on a Clevenger-modified apparatus for every month of one year and assessed on GC/MS and GC/FID detectors for qualitative and quantitative analyses. The influence on content of volatile oils was directly proportional to the environmental variables, temperature and cloudiness, and inversely proportional to precipitation. Among the volatile compounds detected, linalool, β-damascenone, α-ionone, geranyl acetone and β-ionone were the main components, of which β-damascenone and β-ionone were found at the highest concentrations.

In Vitro Anti/Pro-oxidant Activities of R. ferruginea Extract and Its Effect on Glioma Cell Viability: Correlation with Phenolic Compound Content and Effects on Membrane Dynamics

Rapanea ferruginea antioxidant and antitumoral properties were not explored before in literature. This study aimed to investigate these biological activities for the R. ferruginea leaf extract and correlate them with its phenolic content and influence in biological membrane dynamics. Thus, in this study, anti/pro-oxidative properties of R. ferruginea leaf extract by in vitro DPPH and TBARS assays, with respect to the free radical reducing potential and to its activity regarding membrane free radical-induced peroxidation, respectively. Furthermore, preliminary tests related to the extract effect on in vitro glioma cell viability were also performed. In parallel, the phenolic content was detected by HPLC–DAD and included syringic and trans-cinnamic acids, quercetrin, catechin, quercetin, and gallic acid. In an attempt to correlate the biological activity of R. ferruginea extract and its effect on membrane dynamics, the molecular interaction between the extract and a liposomal model with natural-sourced phospholipids was investigated. Location and changes in vibrational, rotational, and translational lipid motions, as well as in the phase state of liposomes, induced by R. ferruginea extract, were monitored by Fourier-transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and UV–visible spectroscopy. In its free form, the extract showed promising in vitro antioxidant properties. Free-form extract (at 1000µxa0g/mL) exposure reduced glioma cell in vitro viability in 40%, as evidenced by MTT tests. Pro-oxidant behavior was observed when the extract was loaded into liposomes. A 70.8% cell viability reduction was achieved with 500 µg/mL of liposome-loaded extract. The compounds ofxa0R. ferruginea extract ordered liposome interface and disorder edits a polar region. Phenolic content, as well as membrane interaction and modulation may have an important role in the oxidative and antitumoral activities of the R. ferruginea leaf extract.

EFFECTS OF SOLVENT, BASE, AND TEMPERATURE IN THE OPTIMISATION OF A NEW CATALYTIC SYSTEM FOR SONOGASHIRA CROSS-COUPLING USING NCP PINCER PALLADACYCLE

The optimisation of a new catalyst system using NCP pincer palladacycle 1 was investigated using the experimental design technique. NCP pincer palladacycle 1 was previously investigated in Suzuki-Miyaura and Heck-Mizoroki cross-couplings and found to be a highly efficient catalyst precursor. In this study, the effects of the type of base (K3PO4 or DABCO), solvent (DMF or dioxane) and reaction temperature (130 or 150 oC) in the second step on the reactional yield in Sonogashira cross-coupling were assessed using the two-factor design. The results showed that temperature is statistically significant in relation to the reaction yield.