Ozone and hydroxyl radicals induced oxidation of glycine

Berger, P.; Leitner, Nathalie Karpel Vel; Doré, M.; Légube, B.

doi:10.1016/s0043-1354(98)00230-9

Cited by 103 publications

(74 citation statements)

References 26 publications

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“…Exposure of hydrogel to ultraviolet light was found to increase the intensity of the oxidized nitrogen peak in X-ray photoelectron spectroscopic spectrum (not shown) indicating oxidation of a higher fraction of amine. Enhanced oxidation of nitrogen by hydroxyl ion in the presence of UV light has also been observed by other researchers [16]. …”

Section: Characterizationsupporting

confidence: 78%

Electrochemical Synthesis of Nitro-Chitosan and Its Performance in Chromium Removal

2013

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Abstract:A synthesized polymeric form of chitosan, electrochemically precipitated and photochemically modified, has been found to have significant value in removal of toxic chromate oxyanions from solution. Fourier Transform Infra-Red (FTIR), Raman and X-ray photoelectron spectroscopy (XPS) indicated that a significant percentage of the amine functional groups were oxidized to nitro groups as a result of reactions with hydroxyl ions formed in the electrochemical process with additional oxidation occurring as a result of exposure to ultra-violet light. The adsorption capacity of the modified chitosan for chromate was investigated in a batch system by taking into account effects of initial concentration, pH of the solution and contact time. Nitro-chitosan showed greater adsorption capacity towards Cr (VI) than other forms of chitosan, with a maximum adsorption of 173 mg/g. It was found that pH 3 is the optimum for adsorption, a Langmuir model is the best fit for the adsorption isotherm, and the kinetics of reaction followed a pseudo second order function. Overall, our results indicate that electrochemical modification of chitosan is an effective method to enhance the reactivity of chitosan towards metals.

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Section: Characterizationsupporting

confidence: 78%

Electrochemical Synthesis of Nitro-Chitosan and Its Performance in Chromium Removal

2013

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“…• pode reagir na cadeia lateral, onde ataca preferencialmente cisteína, histidina, triptofano, metionina e fenilalanina, e, em menores proporções, arginina e asparagina 11 . Os ataques aos aminoácidos que compõem as proteí-nas podem gerar danos como clivagens de ligações com ou sem geração de fragmentos e ligações cruzadas, o que pode ter como 11 .…”

Section: O Estresse Oxidativounclassified

“…Os ataques aos aminoácidos que compõem as proteí-nas podem gerar danos como clivagens de ligações com ou sem geração de fragmentos e ligações cruzadas, o que pode ter como 11 . Na Figura 3 são mostrados os principais produtos dessas reações, destacando-se o tiohidroperóxido (42), cistina (43) 12 , 2-oxo-histidina (44) em equilí-brio com a 2-hidroxi-histidina (45) 13 , metionina sulfóxido (46), metionina sulfona (47) 14 , derivados da arginina, lisina e prolina (48, 49 e 50), nitroacetato (51), oxima (52), hidroxilamina (53) 14 , oxalato (54) 11 e derivados da tirosina (55-60).…”

Section: O Estresse Oxidativounclassified

Estresse oxidativo: relação entre geração de espécies reativas e defesa do organismo

Barreiros¹,

David²,

David³

2006

Quím. Nova

404

149

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Recebido em 1/7/04; aceito em 18/5/05; publicado na web em 24/8/05 OXIDATIVE STRESS: RELATIONS BETWEEN THE FORMATION OF REACTIVE SPECIES AND THE ORGANISM'S DEFENSE. This work describes the mechanism of action of some reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the oxidative stress of the human body, and their consequences on damage to DNA, RNA, proteins and lipids. It also illustrates the defense system of our organism against these ROS and RNS species. The action of nonenzymatic protection systems is reported, with emphasis on micromolecules like Q10 coenzyme, vitamin C, α-tocopherol, carotenoids and flavonoids. The importance of flavonoids is also emphasized, and their body protection mechanism is detailed.Keywords: oxidative stress; antioxidants; reactive species. INTRODUÇÃOAtualmente existe um grande interesse no estudo dos antioxidantes devido, principalmente, às descobertas sobre o efeito dos radicais livres no organismo. A oxidação é parte fundamental da vida aeróbica e do nosso metabolismo e, assim, os radicais livres são produzidos naturalmente ou por alguma disfunção biológica. Esses radicais livres cujo elétron desemparelhado encontra-se centrado nos átomos de oxigênio ou nitrogênio são denominados ERO ou ERN [1][2][3][4] . No organismo, encontram-se envolvidos na produção de energia, fagocitose, regulação do crescimento celular, sinalização intercelular e síntese de substâncias biológicas importantes. No entanto, seu excesso apresenta efeitos prejudiciais, tais como a peroxidação dos lipídios de membrana e agressão às proteínas dos tecidos e das membranas, às enzimas, carboidratos e DNA 5 . Dessa forma, encontram-se relacionados com várias patologias, tais como artrite, choque hemorrágico, doenças do coração, catarata, disfunções cognitivas, câncer e AIDS, podendo ser a causa ou o fator agravante do quadro geral 6 . O excesso de radicais livres no organismo é combatido por antioxidantes produzidos pelo corpo ou absorvidos da dieta. De acordo com Halliwell 3 "Antioxidante é qualquer substância que, quando presente em baixa concentração comparada à do substrato oxidável, regenera o substrato ou previne significativamente a oxidação do mesmo". Os antioxidantes produzidos pelo corpo agem enzimaticamente, a exemplo da GPx, CAT e SOD 2 ou, não-enzimaticamente a exemplo de GSH, peptídeos de histidina, proteínas ligadas ao ferro (transferrina e ferritina), ácido diidrolipóico e CoQH 2 . Além dos antioxidantes produzidos pelo corpo, o organismo utiliza aqueles provenientes da dieta como o a-tocoferol (vitamina-E), β-caroteno (pro-vitamina-A), ácido ascórbico (vitamina-C), e compostos fenólicos onde se destacam os flavonóides e poliflavonóides 4,7 . Dentre os aspectos preventivos, é interessante ressaltar a correlação existente entre atividade antioxidante de substâncias polares e capacidade de inibir ou retardar o aparecimento de células cancerígenas, além de retardar o envelhecimento das células em geral 8 . Outro interesse ligado aos antioxidantes é a sua aplicação na indústria, par...

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“…Even though the products were not investigated in this experiment, research was performed to identify the products of some amino compounds including glycine, the basic component of glyphosate and AMPA 22) .…”

Section: Resultsmentioning

confidence: 99%

Removal of Herbicide Glyphosate in a Drinking Water Treatment System

Navee¹,

Kim²

2009

Korean Journal of Environmental Agriculture

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The removal efficiency of herbicide glyphosate in a drinking water treatment system was investigated. Four major processes of a drinking water treatment system were selected and experiments were performed separately including; treatments by sodium hypochlorite (NaOCl), a sedimentation process by PAC (polyaluminum chloride), ozonation and a GAC (granular activated carbon) treatment. In the sodium hypochlorite experiment, about 50% of the glyphosate was removed by 2 mg/L of hypochlorite and more than 90% was eliminated when 5 mg/L of NaOCl was applied. Also, AMPA, the main metabolite of glyphosate, was treated with hypochlorite. More than 30% of the AMPA was removed by 2 mg/L of hypochlorite and 50% by 5 mg/L. In the PAC experiment, it was determined that more than 60% could be removed. Further experiments were performed and the results indicated that the removed amount was dependent upon the amount of soil and upon the properties of the soil especially that of clay minerals. Ozonation could oxidize glyphosate to its byproducts at about a level of 50%. In contrast, when 1 mg/L of glyphosate was treated with GAC, the amount removed was negligible. The results of this experiment were conclusive. We confirmed that drinking water, which has been contaminated with water polluted with glyphosate can be effectively purified by the application of the drinking water treatment processes currently used

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Ozone and hydroxyl radicals induced oxidation of glycine

Cited by 103 publications

References 26 publications

Electrochemical Synthesis of Nitro-Chitosan and Its Performance in Chromium Removal

Electrochemical Synthesis of Nitro-Chitosan and Its Performance in Chromium Removal

Estresse oxidativo: relação entre geração de espécies reativas e defesa do organismo

Removal of Herbicide Glyphosate in a Drinking Water Treatment System

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