Profiling of colour pigments of chili powders of different origin by high-performance liquid chromatography

The colour pigments of five chili powders of different origins were separated and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC). The similarities and dissimilarities of pigment composition of chili powders were elucidated by principal component analysis (PCA). RP-HPLC separated 50-100 pigment fractions depending on the detection wavelength and on the origin of chili powder. It was found that the pigment composition of chili powders from Malaysia and China and from India and Pakistan show marked similarities while the composition of colour pigments of chili powder from Thailand was different. It was further established that the chromatograms are similar in the first 5-35 min of development, they are highly different between 35 and 75 min and moderately different at the end of the chromatograms. It was concluded that RP-HPLC followed by PCA can be successfully used for the identification of chili powders according to the composition of their colour pigments.     

Magnetic nanoemulsions as drug delivery system for Foscan: Skin permeation and retention in vitro assays for topical application in photodynamic therapy (PDT) of skin cancer

In this work, we performed the synthesis and in vitro characterization of a new class of drug delivery system (DDS) denominated magnetic nanoemulsion (MNE). The association of colloidal nanoparticles with biocompatible magnetic fluids results in a new DDS for application in photodynamic therapy (PDT) and magnetic hyperthermia treatment. It works in a synergic manner with an expected enhancement in tumor damage after minimum drug doses, based on heat dissipation and/or light photosensitization. For this purpose, we investigated the permeation and retention in vitro model using Foscan^® as a photosensitizer incorporated in MNE using a Franz diffusion cell and a biological skin model in biomimetic conditions.     

A numerical study on the SEN-TPB test applied to mode I wood fracture characterization

A numerical study involving the single edge notched-three point bending test was methodically performed to evaluate its adequacy for wood fracture characterization under mode I loading. Stress analysis along the ligament length using cohesive zone modeling allowed understating the influence of the compressive stresses induced by bending on the stress profile for geometrically similar specimens with different sizes. The stress relief region induced by the presence of the crack was identified by a stress analysis procedure along the beam length. A data reduction scheme based on the beam theory and on the crack equivalent concept was then developed considering an approach using a rectangular stress relief region. The method allows estimating the Resistance-curve without monitoring the crack length during propagation. Important remarks regarding the aspects which contribute to explain the size effect phenomenon in wood are highlighted in this study. Following the presented procedure the application of the single edge notched-three point bending test for wood fracture characterization under mode I has become considerably user-friendlier.     

W/O/W Multiple Emulsions Obtained by One‐Step Emulsification Method and Evaluation of the Involved Variables

The effects of some composition variables on the development of multiple emulsions by one‐step method were evaluated and their morphology characterized. The formulations that remained stable during the period of the test were submitted to centrifugation and thermal stress tests. The stability and the morphology of multiple droplets were affected not only by the type and concentration of the surfactants employed, but also by the water/oil ratios used. The results suggest that the formation of multiple droplets could involve a combination of transitional and catastrophic phase inversions. The results provide improved knowledge about the one‐step emulsification method, a simplified process to prepare multiple emulsions when compared to the two‐steps method.     

Development of Vegetable Oil Emulsions with Lamellar Liquid-Crystalline Structures

Emulsions containing vegetable oils and anisotropic phases have especially attractive properties in pharmaceutical technology. They are use as vehicle for different kind of drugs, especially those of topical application. Apart from that, many vegetable oil have pharmacological activity, increasing the necessity for the development of new delivery systems for them. We developed emulsions with vegetable oils at a fixed surfactant ratio and observed the formation of liquid crystalline phases. Nine vegetable oils: Andiroba, Apricot, Avocado, Brazil Nut, Buriti, Cupuassu, Marigold, Passion Fruit and Pequi and mineral oil were tested. Surfactant system was consisted by Steareth-2 and Ceteareth-5. Emulsions were prepared by the emulsion phase inversion (EPI) method, presenting high stability independent on the HLB value. Results indicate that this method could be employed to attain stable emulsions, even if the required HLB value is not known.     

Study of maghemite nanoparticles as prepared and coated with DMSA using Mössbauer spectroscopy with a high velocity resolution

Study of maghemite nanoparticles, native and coated with DMSA as magnetic fluid for biomedical applications, was carried out using Mössbauer spectroscopy with a high velocity resolution at 295 and 90 K. The obtained results demonstrated differences in Mössbauer hyperfine parameters for uncoated and DMSA-coated nanoparticles which were related to the interactions of DMSA molecules with Fe^3+? ions on maghemite nanoparticle’s surface.     

Extract from Eugenia punicifolia is an Antioxidant and Inhibits Enzymes Related to Metabolic Syndrome

The present study aimed to investigate in vitro biological activities of extract of Eugenia punicifolia leaves (EEP), emphasizing the inhibitory activity of enzymes related to metabolic syndrome and its antioxidant effects. The antioxidant activity was analyzed by free radicals scavengers in vitro assays: DPPH·, ABTS^·+, O₂ ^·?, and NO· and a cell-based assay. EEP were tested in inhibitory colorimetric assays using α-amylase, α-glucosidase, xanthine oxidase, and pancreatic lipase enzymes. The EEP exhibited activity in ABTS^·+, DPPH·, and O₂ ^·? scavenger (IC₅₀?=?10.5?±?1.2, 28.84?±?0.54, and 38.12?±?2.6 μg/mL), respectively. EEP did not show cytotoxic effects, and it showed antioxidant activity in cells in a concentration-dependent manner. EEP exhibited inhibition of α-amylase, α-glucosidase, and xanthine oxidase activities in vitro assays (IC₅₀?=?122.8?±?6.3; 2.9?±?0.1; 23.5?±?2.6), respectively; however, EEP did not inhibit the lipase activity. The findings supported that extract of E. punicifolia leaves is a natural antioxidant and inhibitor of enzymes, such as α-amylase, α-glucosidase, and xanthine oxidase, which can result in a reduction in the carbohydrate absorption rate and decrease of risks factors of cardiovascular disease, thereby providing a novel dietary opportunity for the prevention of metabolic syndrome.     

Obtaining nanocomposites of polyamide 6 and cellulose whiskers via extrusion and injection molding

Nanocomposites of polyamides with cellulose whiskers are difficult to obtain by conventional processing of extrusion and injection molding because of the low thermal stability of the cellulosic nanostructures and the relatively high processing temperature of polyamides, which is higher than the temperature of thermal degradation of cellulose whiskers. Thus, in this study cellulose whiskers were coated with polyamide 6 (PA6) in order to increase their thermal stability and prevent the formation of agglomerates. This coating on cellulose whiskers allows their application to obtain nanocomposites with polyamides, whose processing temperatures are relatively high, around 250 °C. Cellulose whiskers (CWs) were obtained from cotton fibers by acid hydrolysis. The freeze-dried CWs were coated with PA6 by dispersing them in formic acid; PA6 was solubilized in this suspension. The cellulose-coated whiskers (CCWs) were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electron microscopy (SEM-FEG) and infrared spectroscopy. SEM-FEG and TG results showed that the PA6 coating on CWs prevented high agglomeration of dried CWs and promoted an increase in their thermal stability from 180 to 280 °C, allowing the use of CCWs to obtain nanocomposites with PA6 using conventional processing routes, such as extrusion and injection molding, at appropriate processing temperatures. In this way, 1 wt% CCWs was used to prepare nanocomposites with PA6. The PA6 + 1CW nanocomposites were compared to neat PA6 without CWs. The samples were characterized by tensile tests and DSC, and the results showed that the PA6 coating on CWs was effective in raising the thermal stability of CWs, improving the dispersion of CWs in the matrix of PA6, resulting in a 45 % increase in the elastic modulus of the nanocomposite with only 1 wt% of coated cellulose whiskers in comparison to neat PA6.     

Use of polystyrene spin-coated compact discs for microimmunoassaying

The analytical potential of polystyrene (PS) spin-coated modified compact discs (CDs) surface as platforms for the development of microarray immunoassays is presented. The surface maintained the optical characteristics of compact discs, obtaining a transparent and smooth film polymer of 70 nm thickness, the track being read (λ 780 nm) without errors in a commercial CD reader/writer. The analytical capability of the methodology was demonstrated through an analysis of a neurotoxic compound (2560 spots per disc), reaching 0.08 μg L⁻¹ as limit of detection. These figures demonstrate the enormous potential of using PS spin-coated compact discs in combination with CD players as an easy-to-operate and portable device to develop lab-on-a-disc analytical applications.     

3,4,5-Trimethoxyphenol: A combined experimental and theoretical thermochemical investigation of its antioxidant capacity

The standard (p^° = 0.1 MPa) molar enthalpies of combustion and sublimation of 3,4,5-trimethoxyphenol were measured, respectively, by static bomb combustion calorimetry in oxygen atmosphere and by Calvet microcalorimetry. From these measurements, the standard molar enthalpy of formation in both the crystalline and gaseous phase, at T = 298.15 K, were derived: ?(643.4 ± 1.9) kJ · mol^?1 and ?(518.1 ± 3.6) kJ · mol^?1, respectively. Density functional theory calculations for this compound and respective phenoxyl radical and phenoxide anion were also performed using the B3LYP functional and extended basis sets, which allowed the theoretical estimation of the gaseous phase standard molar enthalpy of formation through the use of isodesmic reactions and the calculation of the homolytic and heterolytic O–H bond dissociation energies. There is good agreement between the calculated and experimental enthalpy of formation. Substituent effects on the homolytic and heterolytic O–H bond dissociation energies have been analysed.