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Master's Dissertation
DOI
https://doi.org/10.11606/D.46.2018.tde-23042018-122656
Document
Author
Full name
Leandro de Oliveira Royer
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2003
Supervisor
Committee
Bechara, Etelvino Jose Henriques (President)
Mascio, Paolo Di
Oliveira, Marcelo Ganzarolli de
Title in Portuguese
Mecanismos de reação quimiluminescente entre peroxinitrito e metabólitos carbonílicos
Keywords in Portuguese
Biofísica
Estresse oxidativo
Oxidação (Estudo)
Peroxinitrito
Quimioluminescência
Radicais livres
Abstract in Portuguese
O peroxinitrito é um oxidante versátil, sendo responsável por oxidações uni e bieletrônicas, adições nucleofílicas, nitrações, nitrosações, hidroxilações e geração de oxigênio singlete, possuindo papéis fisiológicos e deletérios. Estudos de EPR captação de spin mostraram que compostos carbonílicos podem sofrer abstração de um elétron por peroxinitrito, seguida de consumo de oxigênio e quimiluminescência; p.ex., isobutiraldeído (IBAL), acetoacetona (AA), 3-metilacetoacetpna (MAA), etil acetoacetato (EAA), etil 2-metilacetoacetato (EMAA) e succinilacetona (SA). A emissão de luz é provavelmente devida à espécies excitadas tripletes, formadas a partir da termólise de intermediários dioxetânicos. Os perfis de pH obtidos por consumo total de oxigênio e quimiluminescência em tampão fosfato, apontam o ânion peroxinitrito como oxidante e a forma enólica dos compostos carbonílicos como substratos. A análise de produtos sugere a ocorrência de uma reação em cadeia na presença de oxigênio. Estas reações podem ter importante papel biológico, considerando-se que (i) compostos carbonílicos são ubíquos em sistemas biológicos em condições fisiológicas e patológicas, (ii) peroxinitrito está relacionado a respostas fisiológicas e patológicas, (iii) carbonilas tripletes podem ser vistas como radicais alcoxil e, dessa forma, possuir papel deletério a biomoléculas.
Title in English
Mechanisms of chemiluminescent reaction between peroxynitrite and carbonyl metabolites
Keywords in English
Biophysics
Chemiluminescence
Free radicals
Oxidation (Study)
Oxidative stress
Peroxynitrite
Abstract in English
Peroxynitrite displays an ample repertoire of chemical reactions -one- and two-electron oxidations, nucleophilic addition, nitration, nitrosation, hydroxylation, and singlet oxygen generation conferring it cell toxicity and signalling properties. Carbonyl compounds were shown by EPR spin-trapping to suffer one-electron abstraction by peroxynitrite, which is followed by oxygen consumption and chemiluminescence; e.g., isobutyraldehyde (IBAL), acetoacetone (AA), 3-methylacetoacetone (MAA), ethyl acetoacetate (EAA), ethyl 2-methylacetoacetate (EMAA) and succinylacetone (SA). Light emission probably arises from triplet species formed by the thermolysis of dioxetane intermediates. The pH profiles traced for oxygen uptake ·and chemiluminescence in phosphate buffer point to peroxynitrite anion as the oxidant and enolized carbonyls as the actual substrates. Product analysis suggests that a chain reaction occurs in the presence of oxygen. These reactions may play important biological roles considering that (i) carbonyl compounds are ubiquitous in biological systems under physiological and pathological conditions; (ii) peroxynitrite has been implicated in cell toxicity and signalling; (iii) triplet carbonyls may be viewed as alkoxyl radicals and, therefore, play a deleterious role in biomolecules.
 
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Publishing Date
2018-04-23
 
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