Singlet oxygen reactions with flavonoids. A theoretical-experimental study.

Detection of singlet oxygen emission, λ(max) = 1270 nm, following laser excitation and steady-state methods were employed to measure the total reaction rate constant, k(T), and the reactive reaction rate constant, k(r), for the reaction between singlet oxygen and several flavonoids. Values of k(T) d...

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Autores principales:	Javier Morales, Germán Günther, Antonio L Zanocco, Else Lemp
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1d8a757e0b4f4588a1a0c047ec31314d
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spelling	oai:doaj.org-article:1d8a757e0b4f4588a1a0c047ec31314d2021-11-18T07:13:00ZSinglet oxygen reactions with flavonoids. A theoretical-experimental study.1932-620310.1371/journal.pone.0040548https://doaj.org/article/1d8a757e0b4f4588a1a0c047ec31314d2012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22802966/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203Detection of singlet oxygen emission, λ(max) = 1270 nm, following laser excitation and steady-state methods were employed to measure the total reaction rate constant, k(T), and the reactive reaction rate constant, k(r), for the reaction between singlet oxygen and several flavonoids. Values of k(T) determined in deuterated water, ranging from 2.4×10(7) M(-1) s(-1) to 13.4×10(7) M(-1) s(-1), for rutin and morin, respectively, and the values measured for k(r), ranging from 2.8×10(5) M(-1) s(-1) to 65.7×10(5) M(-1) s(-1) for kaempferol and morin, respectively, being epicatechin and catechin chemically unreactive. These results indicate that all the studied flavonoids are good quenchers of singlet oxygen and could be valuable antioxidants in systems under oxidative stress, in particular if a flavonoid-rich diet was previously consumed. Analysis of the dependence of rate constant values with molecular structure in terms of global descriptors and condensed Fukui functions, resulting from electronic structure calculations, supports the formation of a charge transfer exciplex in all studied reactions. The fraction of exciplex giving reaction products evolves through a hydroperoxide and/or an endoperoxide intermediate produced by singlet oxygen attack on the double bond of the ring C of the flavonoid.Javier MoralesGermán GüntherAntonio L ZanoccoElse LempPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 7, p e40548 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Javier Morales Germán Günther Antonio L Zanocco Else Lemp Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
description	Detection of singlet oxygen emission, λ(max) = 1270 nm, following laser excitation and steady-state methods were employed to measure the total reaction rate constant, k(T), and the reactive reaction rate constant, k(r), for the reaction between singlet oxygen and several flavonoids. Values of k(T) determined in deuterated water, ranging from 2.4×10(7) M(-1) s(-1) to 13.4×10(7) M(-1) s(-1), for rutin and morin, respectively, and the values measured for k(r), ranging from 2.8×10(5) M(-1) s(-1) to 65.7×10(5) M(-1) s(-1) for kaempferol and morin, respectively, being epicatechin and catechin chemically unreactive. These results indicate that all the studied flavonoids are good quenchers of singlet oxygen and could be valuable antioxidants in systems under oxidative stress, in particular if a flavonoid-rich diet was previously consumed. Analysis of the dependence of rate constant values with molecular structure in terms of global descriptors and condensed Fukui functions, resulting from electronic structure calculations, supports the formation of a charge transfer exciplex in all studied reactions. The fraction of exciplex giving reaction products evolves through a hydroperoxide and/or an endoperoxide intermediate produced by singlet oxygen attack on the double bond of the ring C of the flavonoid.
format	article
author	Javier Morales Germán Günther Antonio L Zanocco Else Lemp
author_facet	Javier Morales Germán Günther Antonio L Zanocco Else Lemp
author_sort	Javier Morales
title	Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
title_short	Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
title_full	Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
title_fullStr	Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
title_full_unstemmed	Singlet oxygen reactions with flavonoids. A theoretical-experimental study.
title_sort	singlet oxygen reactions with flavonoids. a theoretical-experimental study.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/1d8a757e0b4f4588a1a0c047ec31314d
work_keys_str_mv	AT javiermorales singletoxygenreactionswithflavonoidsatheoreticalexperimentalstudy AT germangunther singletoxygenreactionswithflavonoidsatheoreticalexperimentalstudy AT antoniolzanocco singletoxygenreactionswithflavonoidsatheoreticalexperimentalstudy AT elselemp singletoxygenreactionswithflavonoidsatheoreticalexperimentalstudy
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Singlet oxygen reactions with flavonoids. A theoretical-experimental study.

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