Assessing Carbohydrate–Carbohydrate Interactions by NMR Spectroscopy: The Trisaccharide Epitope from the Marine Sponge Microciona prolifera

Weak recognition processes : Weak calcium‐mediated carbohydrate–carbohydrate interactions have been detected by DOSY and TRNOESY NMR methods by employing a gold glyconanoparticle as a multivalent system. In addition, 3D models of trisaccharide‐Ca^II‐trisaccharide complexes based on results from molecular dynamics simulations are proposed.

     

By‐products from viticulture and the wine industry: potential as sources of nutrients for ruminants

BACKGROUND: This work aimed to study the chemical composition, in vitro digestibility, ruminal degradability and intestinal digestibility of nutrients of vine shoot (VS), grape marcs (GMG and GMM), white (WL), red (RL) and sherry (SL) wine lees and grape marc plus lees (GML). The effect of polyethylene glycol (PEG) on nutrient availability was also studied. RESULTS: By‐products had variable crude protein (CP) and cell walls (from 44.8 to 203 and from 122 to 741 g kg^?1 dry matter (DM) for CP and neutral detergent fibre (NDF) respectively). DM and CP in vitro digestibility ranged from 0.30 to 0.91 and from 0.51 to 0.84 respectively. The effective ruminal degradability of DM and CP was low (from 0.27 to 0.36 and from 0.34 to 0.53, respectively). The intestinal digestibility of the ruminally undegraded fraction was 0.25 and 0.29 for VS and GMG, respectively. The effect of PEG was different in VS and GMG. CONCLUSION: This is the first information available on ruminal and intestinal availability of nutrients from a diversity of vine and winery by‐products. The use of a combination of the different by‐products studied may represent a valuable source of energy and protein for ruminants. Further research on the effect of diets including these by‐products on animal performance and the quality of products is necessary. Copyright © 2007 Society of Chemical Industry     

The antioxidant effect of a diet rich in Maillard reaction products is attenuated after consumption by healthy male adolescents. In vitro and in vivo comparative study

BACKGROUND: Maillard reaction products (MRPs) are widely consumed as a part of the human diet. A 2 week randomised two‐period crossover trial to determine whether MRP intake affects the antioxidant defence system in male adolescents (11–14 years, n = 18) was carried out using two diets rich and poor in MRPs (brown diet, BD, and white diet, WD, respectively). Fasting blood samples were collected after the dietary intervention periods to measure oxidative status. The in vitro antioxidant activity of the diets was also assessed. RESULTS: The BD had stronger in vitro antioxidant activity to scavenge free radicals and greater ability to reduce lipid peroxidation. However, in the in vivo assay, markers of oxidative damage (serum thiobarbituric acid‐reactive substances and erythrocyte hydroperoxides) and antioxidant defence parameters (serum antioxidants and enzymatic activities of catalase, superoxide dismutase and glutathione peroxidase) were unchanged after the dietary treatments. Only treatment of biological samples with external oxidants revealed higher values of the antioxidant capacity after consumption of the MRP‐rich diet. CONCLUSION: In spite of the higher antioxidant activity of the BD shown in vitro, consumption of diets rich in MRPs does not seem to modify oxidative status in healthy male adolescents. However, a protective effect against induced oxidation was shown. Copyright © 2008 Society of Chemical Industry     

A comparison of three amperometric phenoloxidase–Sonogel–Carbon based biosensors for determination of polyphenols in beers

Three phenoloxidases based biosensors were successfully developed using as electrochemical transducer a new type of electrode recently developed by our group: the “Sonogel–Carbon electrode”. The employed enzymes were Trametes versicolor laccase (Lac), Mushroom tyrosinase (Tyr), and Horseradish peroxidase (HRP). Immobilization step was accomplished by doping the electrode surface with a mixture of the individual enzyme and Nafion ion exchanger as additive-protective. The biosensor responses, optimized in beer real samples, were evaluated for five individual polyphenols. It was found that the developed biosensors were sensitive to nanomolar concentrations of the tested polyphenols. As example, the limit of detection, sensitivity, and response linear range for caffeic acid for Nafion-Lac/Sonogel–Carbon biosensor were 0.06 μmol L⁻¹, 99.6 nA μmol⁻¹ L, and 0.04–2 μmol L⁻¹, respectively. The stability and reproducibility of the biosensors were evaluated by applying them directly to beer real samples. It has been demonstrated that the Nafion-Lac/Sonogel–Carbon system is the more stable with a relative standard deviation of 3.3% (n = 10), maintaining 84% of its stable response for at least three weeks. Estimation of polyphenol index in eight lager beers and a comparison of the results with those obtained by a classical method was carried out.     

G2-S16 Polyanionic Carbosilane Dendrimer Can Reduce HIV-1 Reservoir Formation by Inhibiting Macrophage Cell to Cell Transmission

Human immunodeficiency virus (HIV-1) is still a major problem, not only in developing countries but is also re-emerging in several developed countries, thus the development of new compounds able to inhibit the virus, either for prophylaxis or treatment, is still needed. Nanotechnology has provided the science community with several new tools for biomedical applications. G2-S16 is a polyanionic carbosilane dendrimer capable of inhibiting HIV-1 in vitro and in vivo by interacting directly with viral particles. One of the main barriers for HIV-1 eradication is the reservoirs created in primoinfection. These reservoirs, mainly in T cells, are untargetable by actual drugs or immune system. Thus, one approach is inhibiting HIV-1 from reaching these reservoir cells. In this context, macrophages play a main role as they can deliver viral particles to T cells establishing reservoirs. We showed that G2-S16 dendrimer is capable of inhibiting the infection from infected macrophages to healthy T CD4/CD8 lymphocytes by eliminating HIV-1 infectivity inside macrophages, so they are not able to carry infectious particles to other body locations, thus preventing the reservoirs from forming.     

Chemical characterization and functional properties of selected leafy vegetables for innovative mixed salads

The content of bioactive compounds and antioxidant capacity of nine vegetables of conventional and unconventional utilization in salad mixtures were studied. The total phenolic and flavonoid contents ranged between 39.6–148.5 mg GAE/100g FW and 76.3–217.4 mg QE/100g FW, respectively. Ascorbic acid content ranged between 16.4 and 198.8 mg AAE/100g FW. Antioxidant capacity was assessed using DPPH, FRAP, and ORAC methods; values were in the range of 48.9–245.8 mg TE/100g FW, 67.7–335.8 mg TE/100g FW, and 104.86–833.9 mg TE/100g FW, respectively. Red cabbage, beet greens, parsley, and rocket exhibited the highest antioxidant capacities. Catechin was the most abundant phenolic compound identified in the free fraction, and p‐coumaric acid, quercetin, and caffeic acid in the hydrolyzed fraction. Results suggested that the presence of these phenolics could be of great importance in preventing some chronic and degenerative diseases when regularly consumed. Nonconventional vegetables showed high antioxidant properties, therefore, it is important to promote their consumption.

Practical applications

Not all vegetables have the same phenolic composition, and not all phenolics have the same antioxidant capacity. Knowledge of the bioactive content and antioxidant capacity profile in each vegetable could be of interest to consumers and the food industry for selecting the more suitable leaves to make salad mixtures with high nutritional and functional values. These compounds can prevent some chronic‐degenerative diseases related to oxidative stress, so it is important introduce them regularly into the diet. Moreover, the evaluation of nontraditional vegetables is intended to bring consumers toward a new source of bioactive compounds, prompting their consumption, and providing added value to certain plant parts that are sometimes considered as waste products.     

Effects of solar reflectance and infrared emissivity of rooftops on the thermal comfort of single-family homes in Mexico

This study developed a series of thermal simulations of buildings under the climatic conditions of 20 cities in Mexico. Thermal comfort was analyzed to examine how it is affected by variations in the solar reflectance and infrared emissivity of the exterior surface of a roof in reference housing. The percentage of uncomfortable hours per year was defined in terms of the PPD index (Predicted Percentage of Dissatisfied) as the fraction of time in which PPD > 20%. Optimal combinations were determined for each city, and it was found that the major effects of the solar reflectance and infrared emissivity occur in cities featuring climates whose ambient temperature is not far away from the comfortable temperature range. The maximum reduction of percentage of uncomfortable hours due to combined effect of solar reflectance and infrared emissivity ranging from 1.9% to 40.6%.     

Husk Tomato (Physalis ixocarpa Brot.) Waste as a Promising Source of Pectin: Extraction and Physicochemical Characterization

Husk tomato (Physalis ixocarpa Brot. var. Rendidora) waste was evaluated as a source of specialized pectin, and pectin extracted from this waste was characterized physicochemically. Fruit was blanched for 10 or 15 min and extracted in 0.1 N HCl for 15 to 25 min. Extracted pectin was subjected to physicochemical analysis. For all extraction conditions, the percentage of anhydrogalacturonic acid exceeded 60%, indicating that husk tomato was a good source of pectin. The degree of esterification of pectin molecules was 63% to 91%. The amount of extracted pectin decreased with increasing extraction time. The apparent viscosity of husk tomato pectin showed the characteristic behavior of pseudoplastic fluids. Neutral sugars were identified, and the amounts of 6 sugars (fucose, rhamnose, arabinose, galactose, glucose, and xylose) were quantified. Sugars identified in husk tomato pectin and present in the Rhamnogalacturonan I region, arabinose, galactose, and rhamnose suggest a highly branched structure, which will influence its future applications. Molecular weight values were 542 to 699 kDa, exceeding molecular weight values reported for commercial citrus pectins from 134 to 480 kDa. The extraction process significantly (P < 0.05) influenced the physicochemical properties of pectin. Up to 19.8% from the total amount of pectin in the husk tomato was extracted by 10 min of blanching and 20 min of a more heat treatment. Our findings indicate that husk tomato can be a good alternative source of pectin having highly distinctive physicochemical characteristics.     

Effect of the drying conditions on the microstructure of silica based xerogels and aerogels

Nanostructured silica based xerogels and aerogels are prepared by sol-gel technology, using methyltrimethoxysilane as precursor. The influence of the drying method and conditions on the microstructure of the obtained materials is investigated, since the drying stage has a critical influence on their porosity. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Although the supercritical fluids drying technique is more expensive and hazardous than the atmospheric pressure drying, it is well known that aerogels are less dense than the xerogels due to less pore shrinkage. However, the ideal situation would be to use atmospheric pressure drying in conditions that minimize the pore collapse. Therefore, in this work, different temperature cycles for atmospheric pressure drying and two heating rates for the supercritical fluids drying are tested to study the gels' shrinkage by analyzing the density and porosity properties of the final materials. The best materials obtained are aerogels dried with the lower heating rate (approximately 80 degrees C/h), since they exhibit very low bulk density (approximately 50 kg/m3), high porosity (95%)-mainly micro and mesopores, high surface area (approximately 500 m2/g), moderate flexibility and a remarkable hydrophobic character (>140 degrees). It was proved that the temperature cycles of atmospheric pressure drying can be tuned to obtain xerogels with properties comparable to those of aerogels, having a bulk density only approximately15 kg/m3 higher. All the synthesized materials fulfill the requirements for application as insulators in Space environments.