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Previsão da acidez, de compostos fenólicos por métodos computacionais. Contribuição para o esclarecimento da função antioxidante
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Resumo(s)
As propriedades antioxidantes que certos compostos apresentam devem-se à sua acção neutralizadora de radicais livres. Neste contexto os compostos (poli)fenólicos são vistos como líderes, pois apresentam actividade antioxidante, que se espelha nas propriedades antinflamatórias e anticancerígenas, entre outras, e, consequentemente, de antienvelhecimento. A acção inibitória dos radicais livres processa-se por meio de transferência do átomo de H do grupo OH fenólico, resultando a actividade antioxidante da energia da ligação O–H. Esta energia de ligação pode determinar-se, experimentalmente, por medição das afinidades electrónicas dos radicais fenoxilo ou das entalpias de formação dos aniões fenóxido. No presente trabalho pretende-se fazer uma abordagem a este assunto por meio de técnicas computacionais, que permitirão avaliar a relação estrutura-actividade de fenóis substituídos – cromanóis, trolox, vitamina E, entre outros, com o objectivo de investigar a influência de substituintes na acidez. A relevância do presente estudo prende-se com o facto de, conhecendo a acidez dos compostos, ser mais fácil o desenvolvimento de novos fármacos.
Certain compounds exhibit antioxidant properties due to their neutralizing action towards damaging free radicals. In this context (poly)phenolic compounds are seen as the leading family of antioxidant activity, which is reflected in anticancer and anti-inflammatory properties among other, and hence as anti-aging powerful tools. The inhibitory action of the free radicals takes place by H atom transfer from the phenolic OH group. The resulting antioxidant activity arises from the binding energy of the O–H bond. This binding energy can be experimentally determined by measuring either the electronic affinity of the phenoxy radicals or the formation enthalpy of the phenoxide anions, for a given compound. As part of a wider strategy, In the present work the aim is to assess this issue by computational techniques, which allow evaluating the structure-activity relationship of substituted phenols – cromanol, trolox and derivatives, vitamin E, among others – with the aim to investigate the role of substituent groups on the acidity and antioxidant activity at Large. The relevance of this study relates to the fact that knowing the acidity of the compounds, it is easier to develop new drugs.
Certain compounds exhibit antioxidant properties due to their neutralizing action towards damaging free radicals. In this context (poly)phenolic compounds are seen as the leading family of antioxidant activity, which is reflected in anticancer and anti-inflammatory properties among other, and hence as anti-aging powerful tools. The inhibitory action of the free radicals takes place by H atom transfer from the phenolic OH group. The resulting antioxidant activity arises from the binding energy of the O–H bond. This binding energy can be experimentally determined by measuring either the electronic affinity of the phenoxy radicals or the formation enthalpy of the phenoxide anions, for a given compound. As part of a wider strategy, In the present work the aim is to assess this issue by computational techniques, which allow evaluating the structure-activity relationship of substituted phenols – cromanol, trolox and derivatives, vitamin E, among others – with the aim to investigate the role of substituent groups on the acidity and antioxidant activity at Large. The relevance of this study relates to the fact that knowing the acidity of the compounds, it is easier to develop new drugs.
Descrição
Tese de mestrado em Química, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2012
Palavras-chave
Acidez Antioxidante Cromanol DFT Dimetoxifenol Fenóis Tocoferol Vitamina E Teses de mestrado - 2012