Drag reduction by polyethylene glycol in the tail arterial bed of normotensive and hypertensive rats

This study was designed to evaluate the effect of drag reducer polymers (DRP) on arteries from normotensive (Wistar) and spontaneously hypertensive rats (SHR). Polyethylene glycol (PEG 4000 at 5000 ppm) was perfused in the tail arterial bed with (E+) and without endothelium (E-) from male, adult Wistar (N = 14) and SHR (N = 13) animals under basal conditions (constant flow at 2.5 mL/min). In these preparations, flow-pressure curves (1.5 to 10 mL/min) were constructed before and 1 h after PEG 4000 perfusion. Afterwards, the tail arterial bed was fixed and the internal diameters of the arteries were then measured by microscopy and drag reduction was assessed based on the values of wall shear stress (WSS) by computational simulation. In Wistar and SHR groups, perfusion of PEG 4000 significantly reduced pulsatile pressure (Wistar/E+: 17.5 ± 2.8; SHR/E+: 16.3 ± 2.7%), WSS (Wistar/E+: 36; SHR/E+: 40%) and the flow-pressure response. The E- reduced the effects of PEG 4000 on arteries from both groups, suggesting that endothelial damage decreased the effect of PEG 4000 as a DRP. Moreover, the effects of PEG 4000 were more pronounced in the tail arterial bed from SHR compared to Wistar rats. In conclusion, these data demonstrated for the first time that PEG 4000 was more effective in reducing the pressure-flow response as well as WSS in the tail arterial bed of hypertensive than of normotensive rats and these effects were amplified by, but not dependent on, endothelial integrity. Thus, these results show an additional mechanism of action of this polymer besides its mechanical effect through the release and/or bioavailability of endothelial factors.

Biocompósitos de matriz glioxal-fenol reforçada com celulose microcristalina

Glioxal pode ser obtido a partir de biomassa (como da oxidação de lipídeos) e não é tóxico ou volátil, tendo sido por isso utilizado no presente trabalho como substituto de formaldeído na preparação de resina fenólica do tipo novolaca, sendo usado como catalisador o ácido oxálico, que também pode ser obtido de fontes renováveis. A resina glioxal-fenol foi utilizada na preparação de compósitos reforçados com celulose microcristalina (CM, 30, 50 e 70% em massa), uma celulose com elevada área superficial. As imagens de microscopia eletrônica de varredura (MEV) das superfícies fraturadas demonstraram que os compósitos apresentaram boa interface reforço/matriz, consequência da elevada área superficial da CM e presença de grupos polares (hidroxilas) tanto na matriz como na celulose, o que permitiu a formação de ligações hidrogênio, favorecendo a compatibilidade entre ambas. A análise térmica dinâmico-mecânica (DMTA) demonstrou que todos os compósitos apresentaram elevado módulo de armazenamento à temperatura ambiente. Além disso, o compósito reforçado com 30% de CM apresentou baixa absorção de água, comparável à do termorrígido fenólico, que é utilizado em escala industrial. Os resultados demonstraram que compósitos com boas propriedades podem ser preparados usando elevada proporção de materiais obtidos de biomassa.

The effect of using mixed initiator systems on the efficiency of photopolymerization of dental resins

A study was performed in order to determine the efficiency of the simultaneous use of the photoinitiators phenylpropanedione (PPD) and camphorquinone (CQ) in the polymerization of acrylic polymers and evaluate possible mechanisms leading to synergism or antagonism. It was found that efficiencies of both initiators taken individually are higher than that of their mixture, indicating that when both dyes are used simultaneously there will be an energy transfer from the more efficient initiator (CQ) to the less efficient one (PPD). Also, there was no proof of any reaction between the amine present in the CQ formulation and the PPD excited state.

Dextranas em açúcares do estado de São Paulo

The characterization of dextran in sugars by size exclusion chromatography (SEC) has been carried out according to the number-average molecular weight (Mn), the weight-average molecular weight (Mw), the Z-average molecular weight (Mz), and the polydispersity (Mw/Mn). The results suggest that all the analyzed thirty sugar samples from São Paulo state were contaminated with two or three different dextran polymers. The collected data clearly point out that the total dextran content together with the mass distribution parameters Mw, Mn, Mz, and Mw/Mn should be considered during the evaluation of the quality of the sugar used for the cachaça sweeting process.

Síntese de poli(1,1'-ferrocenilenovinileno) via acoplamento de McMurry

Com base nas grandes modificações das propriedades de materiais poliméricos resultantes da inclusão de unidades organometálicas, descrevem-se neste trabalho a síntese e a caracterização de um polímero organometálico conjugado com estrutura semelhante à de poli(p-fenilenovinileno) (PPV), o qual apresenta grupos 1,1'-ferrocenileno no lugar de 1,4fenileno em sua cadeia principal. Sintetizado por meio de reação de acoplamento de McMurry de 1,1'-ferrocenodialdeído, o poli(1,1'-ferrocenilenovinileno) (PFV) se apresentou na forma de um sólido de cor laranja, amorfo e insolúvel tanto em solventes polares quanto em apolares. Para caracterização do PFV, empregaram-se os métodos de espectroscopia no infravermelho (FTIR), espectroscopia Raman e análise termogravimétrica (TGA).

Nanochromics: old materials, new structures and architectures for high performance devices

Due to the development of nanoscience, the interest in electrochromism has increased and new assemblies of electrochromic materials at nanoscale leading to higher efficiencies and chromatic contrasts, low switching times and the possibility of color tuning have been developed. These advantages are reached due to the extensive surface area found in nanomaterials and the large amount of organic electrochromic molecules that can be easily attached onto inorganic nanoparticles, as TiO2 or SiO2. Moreover, the direct contact between electrolyte and nanomaterials produces high ionic transfer rates, leading to fast charge compensation, which is essential for high performance electrochromic electrodes. Recently, the layer-by-layer technique was presented as an interesting way to produce different architectures by the combination of both electrochromic nanoparticles and polymers. The present paper shows some of the newest insights into nanochromic science.

Caracterização físico-química de polpas de frutos da Amazônia e sua correlação com a atividade anti-radical livre

Características físico-químicas (cor, pH, acidez total titulável, sólidos solúveis totais, conteúdo de lipídios e umidade) e níveis de compostos bioativos (ácido ascórbico, fenólicos totais) foram determinados em quinze amostras de polpas de frutos procedentes da região Amazônica (abiu, acerola, açaí, araçá-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo). A atividade de radicais livres foi avaliada pelo método de ABTS. Algumas polpas apresentaram alta potencialidade antioxidante, associada com a atividade antirradicais livres obtida e os conteúdos dos componentes bioativos como compostos fenólicos e ácido ascórbico, destacando-se acerola e acaí. O conteúdo total de compostos fenólicos foi correlacionado à capacidade antioxidante das polpas.

Natural antioxidant from yerba maté (Ilex paraguariensis St. Hil.) prevents hamburger peroxidation

The aim of this study was to evaluate whether yerba maté alcoholic extracts at very low concentrations (0.01 and 0.1%), prevent/retard lipid peroxidation in beef hamburgers without impairing sensory acceptability. For this TBARs and hexanal levels, fatty acid profile and cholesterol oxides were evaluated as oxidation parameters in beef hamburgers during 90 days' storage. The addition of 0.01% yerba maté ethanolic extracts proved inefficient in restraining the lipid peroxidation while the addition of 0.1% resulted in efficient antioxidant activity. Sensory evaluation of hamburger containing 0.1% yerba maté ethanolic extracts showed good acceptability. Yerba maté ethanolic extracts could entirely or partially replace the phenolic synthetic antioxidants in beef hamburgers only when used at above legally allowed concentrations for antioxidant additives (0.01%).

Biodisponibilidade de ácidos fenólicos

The daily intake of phenolic compounds does not necessarily reflect the dose at which they reach the physiological targets in the organisms. The biological activity of phenolic compounds metabolites found in blood, organs and target tissues, as a result of digestive and hepatic activity, may differ from those of the native forms of the substances. This review discusses the absorption and metabolism of phenolic acids, a class of phenolic compounds abundant in food, and the methodologies used for evaluation of bioavailability.

Template-based fluoroethylenepropylene piezoelectrets with tubular channels for transducer applications

We describe the concept, the fabrication, and the most relevant properties of a piezoelectric-polymer system: Two fluoroethylenepropylene (FEP) films with good electret properties are laminated around a specifically designed and prepared polytetrafluoroethylene (PTFE) template at 300 degrees C. After removing the PTFE template, a two-layer FEP film with open tubular channels is obtained. For electric charging, the two-layer FEP system is subjected to a high electric field. The resulting dielectric barrier discharges inside the tubular channels yield a ferroelectret with high piezoelectricity. d(33) coefficients of up to 160 pC/N have already been achieved on the ferroelectret films. After charging at suitable elevated temperatures, the piezoelectricity is stable at temperatures of at least 130 degrees C. Advantages of the transducer films include ease of fabrication at laboratory or industrial scales, a wide range of possible geometrical and processing parameters, straightforward control of the uniformity of the polymer system, flexibility, and versatility of the soft ferroelectrets, and a large potential for device applications e.g., in the areas of biomedicine, communications, production engineering, sensor systems, environmental monitoring, etc.

Evaluation of Antiproliferative, Anti-Type 2 Diabetes, and Antihypertension Potentials of Ellagitannins from Strawberries (Fragaria x ananassa Duch.) Using In Vitro Models

Strawberries represent the main source of ellagic acid derivatives in the Brazilian diet, corresponding to more than 50% of all phenolic compounds found in the fruit. There is a particular interest in the determination of the ellagic acid content in fruits because of possible chemopreventive benefits. In the present study, the potential health benefits of purified ellagitannins from strawberries were evaluated in relation to the antiproliferative activity and in vitro inhibition of alpha-amylase, alpha-glucosidase, and angiotensin I-converting enzyme (ACE) relevant for potential management of hyperglycemia and hypertension. Therefore, a comparison among ellagic acid, purified ellagitannins, and a strawberry extract was done to evaluate the possible synergistic effects of phenolics. In relation to the antiproliferative activity, it was observed that ellagic acid had the highest percentage inhibition of cell proliferation. The strawberry extract had lower efficacy in inhibiting the cell proliferation, indicating that in the case of this fruit there is no synergism. Purified ellagitannins had high alpha-amylase and ACE inhibitory activities. However, these compounds had low alpha-glucosidase inhibitory activity. These results suggested that the ellagitannins and ellagic acid have good potential for the management of hyperglycemia and hypertension linked to type 2 diabetes. However, further studies with animal and human models are needed to advance the in vitro assay-based biochemical rationale from this study.

Evaluation of Indigenous Grains from the Peruvian Andean Region for Antidiabetes and Antihypertension Potential Using In Vitro Methods

The health-relevant functionality of 10 thermally processed Peruvian Andean grains (five cereals, three pseudocereals, and two legumes) was evaluated for potential type 2 diabetes-relevant antihyperglycemia and antihypertension activity using in vitro enzyme assays. Inhibition of enzymes relevant for managing early stages of type 2 diabetes such as hyperglycemia-relevant alpha-glucosidase and alpha-amylase and hypertension-relevant angiotensin I-converting enzyme (ACE) were assayed along with the total phenolic content, phenolic profiles, and antioxidant activity based on the 1,1-diphenyl-2-picrylhydrazyl radical assay. Purple corn (Zea mays L.) (cereal) exhibited high free radical scavenging-linked antioxidant activity (77%) and had the highest total phenolic content (8 +/- 1 mg of gallic acid equivalents/g of sample weight) and alpha-glucosidase inhibitory activity (51% at 5 mg of sample weight). The major phenolic compound in this cereal was protocatechuic acid (287 +/- 15 mu g/g of sample weight). Pseudocereals such as Quinoa (Chenopodium quinoa Willd) and Kaniwa (Chenopodium pallidicaule Aellen) were rich in quercetin derivatives (1,131 +/- 56 and 943 +/- 35 mu g [expressed as quercetin aglycone]/g of sample weight, respectively) and had the highest antioxidant activity (86% and 75%, respectively). Andean legumes (Lupinus mutabilis cultivars SLP-1 and H-6) inhibited significantly the hypertension-relevant ACE (52% at 5 mg of sample weight). No alpha-amylase inhibitory activity was found in any of the evaluated Andean grains. This in vitro study indicates the potential of combination of Andean whole grain cereals, pseudocereals, and legumes to develop effective dietary strategies for managing type 2 diabetes and associated hypertension and provides the rationale for animal and clinical studies.

Evaluation of Antihyperglycemia and Antihypertension Potential of Native Peruvian Fruits Using In Vitro Models

Local food diversity and traditional crops are essential for cost-effective management of the global epidemic of type 2 diabetes and associated complications of hypertension. Water and 12% ethanol extracts of native Peruvian fruits such as Lucuma (Pouteria lucuma), Pacae (Inga feuille), Papayita arequipena (Carica pubescens), Capuli (Prunus capuli), Aguaymanto (Physalis peruviana), and Algarrobo (Prosopis pallida) were evaluated for total phenolics, antioxidant activity based on 2, 2-diphenyl-1-picrylhydrazyl radical scavenging assay, and functionality such as in vitro inhibition of alpha-amylase, alpha-glucosidase, and angiotensin I-converting enzyme (ACE) relevant for potential management of hyperglycemia and hypertension linked to type 2 diabetes. The total phenolic content ranged from 3.2 (Aguaymanto) to 11.4 (Lucuma fruit) mg/g of sample dry weight. A significant positive correlation was found between total phenolic content and antioxidant activity for the ethanolic extracts. No phenolic compound was detected in Lucuma (fruit and powder) and Pacae. Aqueous extracts from Lucuma and Algarrobo had the highest alpha-glucosidase inhibitory activities. Papayita arequipena and Algarrobo had significant ACE inhibitory activities reflecting antihypertensive potential. These in vitro results point to the excellent potential of Peruvian fruits for food-based strategies for complementing effective antidiabetes and antihypertension solutions based on further animal and clinical studies.

Antidiabetes and antihypertension potential of commonly consumed carbohydrate sweeteners using in vitro models

Commonly consumed carbohydrate sweeteners derived from sugar cane, palm, and corn (syrups) were investigated to determine their potential to inhibit key enzymes relevant to Type 2 diabetes and hypertension based on the total phenolic content and antioxidant activity using in vitro models. Among sugar cane derivatives, brown sugars showed higher antidiabetes potential than white sugars; nevertheless, no angiotensin I-converting enzyme (ACE) inhibition was detected in both sugar classes. Brown sugar from Peru and Mauritius (dark muscovado) had the highest total phenolic content and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, which correlated with a moderate inhibition of yeast alpha-glucosidase without showing a significant effect on porcine pancreatic alpha-amylase activity. In addition, chlorogenic acid quantified by high-performance liquid chromatography was detected in these sugars (128 +/- 6 and 144 +/- 2 mu g/g of sample weight, respectively). Date sugar exhibited high alpha-glucosidase, alpha-amylase, and ACE inhibitory activities that correlated with high total phenolic content and antioxidant activity. Neither phenolic compounds or antioxidant activity was detected in corn syrups, indicating that nonphenolic factors may be involved in their significant ability to inhibit alpha-glucosidase, alpha-amylase, and ACE. This study provides a strong biochemical rationale for further in vivo studies and useful information to make better dietary sweetener choices for Type 2 diabetes and hypertension management.

Seasonality Role on the Phenolics from Cultivated Baccharis dracunculifolia

Baccharis dracunculifolia is the source of Brazilian green propolis (BGP). Considering the broad spectrum of biological activities attributed to green proplis, B. dracunculifolia has a great potential for the development of new cosmetic and pharmaceutical products. In this work, the cultivation of 10 different populations of native B. dracunculifolia had been undertaken aiming to determine the role of seasonality on its phenolic compounds. For this purpose, fruits of this plant were collected from populations of 10 different regions, and 100 individuals of each population were cultivated in an experimental area of 1800 m(2). With respect to cultivation, the yields of dry plant, essential oil and crude extract were measured monthly resulting in mean values of 399 +/- 80 g, 0.6 +/- 0.1% and 20 +/- 4%, respectively. The HPLC analysis allowed detecting seven phenolic compounds: caffeic acid, ferulic acid, aromadendrin-4'-methyl ether (AME), isosakuranetin, artepillin C, baccharin and 2-dimethyl-6-carboxyethenyl-2H-1-benzopyran acid, which were the major ones throughout the 1-year monthly analysis. Caffeic acid was detected in all cultivated populations with mean of 4.0%. AME displayed the wide variation in relation to other compounds showing means values of 0.65 +/- 0.13% at last quarter. Isosakuranetin and artepillin C showed increasing concentrations with values between 0% and 1.4% and 0% and 1.09%, respectively. The obtained results allow suggesting that the best time for harvesting this plant, in order to obtain good qualitative and quantitative results for these phenolic compounds, is between December and April.