Encontrados 15 documentos, a visualizar página 1 de 2
Aromatic hydroxylation reactions by electrogenerated HO radicals : a kinetic study
Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. DulceThe oxidation of benzoic acid (BA) and of 4-hydroxybenzoic acid (4-HBA) by galvanostatic electrolysis with simultaneous oxygen evolution, using BDD or Pt as anode materials is studied. Results concerning the oxidation kinetics as well as the identification and quantification of hydroxylated products are reported. First order kinetics are used to describe the consumption rates of both compounds despite of the an...
Characterization of antioxidants activity in a microfluidic channel
Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. Dulce; Thouin, L.; Sella, C.Antioxidant is the common designation for substances that have a potential action in the prevention of oxidative stress. The characterization of the reactivity of these substances has attracted the attention of many researchers, with the aim to establish correlations between the intake of antioxidants and health maintenance or to detect early stages of diseases associated with oxidative stress. The measurement ...
Electrochemical generation of hydroxyl radicals for protein oxidation studies
Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. Dulce; Marcos, João Carlos; Rodrigues, JoãoIn the last decades, different studies shown that the increase in oxidative stress is associated with the risk factors implicated in the pathophysiology of many chronic diseases. Therefore it is important to evaluate the role that hydroxyl radicals-mediated damage may play in major human disorders. Proteins are important targets as they compose ca. 70% of cells. To understand the impact of specific modification...
Evaluation of antioxidant radical scavenging activity by means of electrogenera...
Oliveira, Raquel; Brault, Justine; Bento, M. Fátima; Geraldo, M. DulceHydroxyl radical is one of the most reactive radicals. The generation of HO• represents an important task in different areas, such as organic synthesis [1], oxidative stress studies [2] and in the detoxification of effluents [3]. The generation of hydroxyl radicals based on metal catalyzed decomposition of hydrogen peroxide, by Fenton or Fenton-like reactions, is the most spread method. In the context of the mi...
Estudo da capacidade antioxidante de compostos fenólicos baseado em electrólise...
Pereira, Nelson; Santos, Carlos; Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. DulceA caracterização da capacidade antioxidante de moléculas e de alimentos tem captado a atenção de investigadores em diferentes áreas dada a ação dos antioxidantes no retardamento de processos oxidativos que estão na origem do stresse oxidativo. Dentro dos métodos convencionais utilizados na avaliação da capacidade antioxidante destacam-se os métodos óticos baseados na análise da resposta do antioxidante ao ataqu...
Estudo dos danos oxidativos provocados em proteínas por radicais hidroxilo gera...
Santos, Carlos; Pereira, Nelson; Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. Dulce; Marcos, João CarlosOs radicais HO são espécies altamente reativas usualmente designadas de espécies reativas de oxigénio (ROS). Estas espécies podem provocar danos importantes em organismos vivos, estando na origem do stresse oxidativo1, 2. As proteínas, dada a sua abundância em células, constituem alvos importantes do ataque por ROS, sendo assim relevante caracterizar as suas modificações oxidativas. Neste contexto é importante ...
Hydroxylation of benzoic acid by electrochemical generated hydroxyl radicals
Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. DulceThe generation of hydroxyl radicals is an important process in many applications such as organic synthesis [1], oxidative stress studies [2] and detoxification of effluents [3]. Due to the high instability of these radicals they are usually produced in situ by means of different methods, such as disproportionation of peroxynitrous acid or dissociation of hydrogen peroxide by UV action. The generation of hydroxy...
Voltammetric detection of Domoic Acid at a multiwalled carbon-nanotube electrode
Bento, M. Fátima; Geraldo, M. Dulce; Oliveira, Raquel; Teixeira, Cecília; González-Romero, ElisaDomoic acid (DA) is a heterocyclic amino acid and a structural analogue of kainic acid and proline. In mammals, including humans, DA acts as a neurotoxin, causing loss of short-term memory, brain damage and, in severe cases, death. DA enters in the food chain via phytoplankton, which serves as food to marine organisms as crustaceans, anchovies and sardines. DA concentrations at the tissues of these marine speci...
Cyclic voltammetry studies of biotoxins on nanostrutured screen printed electrodes
Teixeira, Cecília; Bento, M. Fátima; Geraldo, M. Dulce; González-Romero, ElisaThe methods of analysis recognized for the detection of biotoxins marine in bivalve live molluscs have been modified by the European Commission 15/2011 in January 10 (2011) substituting the Regulation (CE) n º 2074/2005. Concurrently, bioassay's method in mice will not be able to continue used after December 31, 2014, for what it will be necessary that the different laboratories that nowadays carry out these bi...
Avaliação da actividade antioxidante dos ácidos úrico e ascórbico pelo método RACE
Oliveira, Raquel; Yilmaz, Pinar; Yavas, Pinar; Geraldo, M. Dulce; Bento, M. FátimaOs antioxidantes desempenham um papel importante na prevenção e tratamento de doenças relacionadas com o envelhecimento, sendo por isso muito usados em produtos farmacêuticos, suplementos dietéticos e cosméticos. Numerosos estudos têm sido desenvolvidos no sentido de estabelecer os mecanismos de acção destas substâncias [1], determinar a actividade antioxidante de compostos [2] e definir índices de capacidade a...
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