Weekend ethanol consumption and high-sucrose diet: resveratrol effects on energy expenditure, substrate oxidation, lipid profile, oxidative stress and hepatic energy metabolism

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of electrochemical oxidation and determination of albendazole using a glassy carbon-rotating disk electrode

In this work, electrochemical oxidation of albendazole (ABZ) was carried out using a glassy carbon-rotating disk electrode. Development of electroanalytical methodology for ABZ quantification in pharmaceutical formulations was also proposed by using linear sweep voltammetric technique. Electrochemical oxidation is observed for ABZ at E 1/2 = 0.99:V vs. Ag/AgCl sat, when an anodic wave is observed. Kinetic parameters obtained for ABZ oxidation exhibited a standard heterogeneous rate constant for the electrodic process equal to (1.51 ± 0.07) ± 10 -5:cm:s -1, with a αn a value equal to 0.76. Limiting current dependence against ABZ concentration exhibited linearity on 5.0 ± 10 -5 to 1.0 ± 10 -2:mol:l -1 range, being obtained a detection limit of 2.4 ± 10 -5:mol:l -1. Proposed methodology was applied to ABZ quantification in pharmaceutical formulations. © 2005 Elsevier SAS. All rights reserved.

The effect of pH on horseradish peroxidase-catalyzed oxidation of melatonin: Production of N1-acetyl-N2-formyl-5- methoxykynuramine versus radical-mediated degradation

There is a growing body of evidence that melatonin and its oxidation product, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), have anti-inflammatory properties. From a nutritional point of view, the discovery of melatonin in plant tissues emphasizes the importance of its relationship with plant peroxidases. Here we found that the pH of the reaction mixture has a profound influence in the reaction rate and products distribution when melatonin is oxidized by the plant enzyme horseradish peroxidase. At pH 5.5, 1 mm of melatonin was almost completely oxidized within 2 min, whereas only about 3% was consumed at pH 7.4. However, the relative yield of AFMK was higher in physiological pH. Radical-mediated oxidation products, including 2-hydroxymelatonin, a dimer of 2-hydroxymelatonin and O-demethylated dimer of melatonin account for the fast consumption of melatonin at pH 5.5. The higher production of AFMK at pH 7.4 was explained by the involvement of compound III of peroxidases as evidenced by spectral studies. On the other hand, the fast oxidative degradation at pH 5.5 was explained by the classic peroxidase cycle. © 2007 The Authors.

Electrocatalytic activity under oscillatory regime: The electro-oxidation of formic acid on ordered Pt3Sn intermetallic phase

Despite the considerable progress in the understanding of the mechanistic aspects of the oscillatory electro-oxidation of C1 molecules, there are apparently no systematic studies concerning the impact of surface modifiers on the oscillation dynamics. Herein we communicate on the oscillatory electro-oxidation of formic acid on ordered Pt3Sn intermetallic phase, and compare the results with those obtained on a polycrystalline platinum electrode. Overall, the obtained results were very reproducible, robust and allowed a detailed analysis on the correlation between the catalytic activity and the oscillation dynamics. The presence of Sn in the intermetallic electrode promotes drastic effects on the oscillatory dynamics. The decrease in the mean electrode potential and in the oscillation frequency, as well as the pronounced increase in the number oscillations (and also in the oscillation time), was discussed in connection with the substantial catalytic enhancement of the Pt3Sn towards the electro-oxidation of formic acid. The self-organized potential oscillations were used to probe the electrocatalytic activity of the Pt3Sn electrode and compare it with that for polycrystalline Pt. The presence of Sn resulted in a significant decrease (2-11 times, depending on the applied current) of the rate of surface poisoning. © 2012 Elsevier B.V.

Electrochemical oxidation of wastewater containing aromatic amines using a flow electrolytic reactor

Aromatic amines are environmental pollutants and represent one of the most important classes of industrial and natural chemicals. Some types of complex effluents containing these chemical species, mainly those originated from chemicals plants are not fully efficiently treated by conventional processes. In this work, the use of electrochemical technology through an electrolytic pilot scale flow reactor is considered for treatment of wastewater of a chemical industry manufacturer of antioxidant and anti-ozonant substances used in rubber. Experimental results showed that was possible to remove between 65% and 95% of apparent colour and chemical oxygen demand removal between 30 and 90% in 60 min of treatment, with energy consumption rate from 26 kWh m-3 to 31 kWh m-3. Absorbance, total organic carbon and toxicity analyses resulted in no formation of toxic by-products. The results suggest that the presented electrochemical process is a suitable method for treating this type of wastewater, mainly when pre-treated by aeration. Copyright © 2013 Inderscience Enterprises Ltd.

The electro-oxidation of carbon monoxide and ethanol on supported Pt nanoparticles: The influence of the support and catalyst microstructure

The sluggish kinetics of ethanol oxidation on Pt-based electrodes is one of the major drawbacks to its use as a liquid fuel in direct ethanol fuel cells, and considerable efforts have been made to improve the reaction kinetics. Herein, we report an investigation on the effect of the Pt microstructure (well-dispersed versus agglomerated nanoparticles) and the catalyst support (carbon Vulcan, SnO2, and RuO2) on the rate of the electrochemical oxidation of ethanol and its major adsorbed intermediate, namely, carbon monoxide. By using several structural characterization techniques such as X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy, along with potentiodynamic and potentiostatic electrochemical experiments, we show that by altering both the Pt microstructure and the support, the rate of the electrochemical oxidation of ethanol can be improved up to a factor of 12 times compared to well-dispersed carbon-supported Pt nanoparticles. As a result of a combined effect, the interaction of Pt agglomerates with SnO2 yielded the highest current densities among all materials studied. The differences in the activity are discussed in terms of structural and electronic properties as well as by mass transport effects, providing valuable insights to the development of more active materials. © 2013 Springer-Verlag Berlin Heidelberg.

Photoelectrochemical Hydrogen Generation and Concomitant Organic Dye Oxidation under TiO2 Nanotube

The present work describes the photoelectrochemical hydrogen generation during a photodegradation of an organic compound. For this, it was chosen the reactive black 5 dye as a model of organic pollutant and its oxidation under TiO2 nanotube in a two compartment cell. The photoelectrocatalysis is conducted in 0.1 mol L-1 Na2SO4 pH 6 medium under photoanode biased at +1.0 V (SCE) and activated by UV and visible light using 150W Xe-Arc lamp (Oriel) and 125 W Hg lamp (Osram). The concomitant hydrogen production was monitored at cathodic compartment using a Pt cathode. Using optimized condition of Na2SO4 0.1 mol L-1 pH 6 as supporting electrolyte, applied potential of +1.0V it was verified 100% of discoloration and 72% of TOC removal of 1.0 x 10(-5) mol L-1 Reactive Black 5 dye after 120 min of treatment (rate constant of 10.6 x10(-2) min(-1)). The concomitant hydrogen generation was 44% in this condition.