Reactivity of flavonoids with 1-hydroxyethyl radical: a gamma-radiolysis study.
We have investigated the reactivity between 11 flavonoids and 1-hydroxyethyl radical (HER). HER was recently implicated in many liver injuries induced by ethanol intoxication. In this study, HER was generated by radiolysis; due to its reaction rate, HER is well known to be responsible for solute degradation in irradiated ethanol. Flavonoid ethanol solutions were irradiated with gamma-rays and the flavonoid degradation was followed by HLPC. We observed the degradation of flavonols while all other flavonoids (flavones, flavanones, dihydroflavonols, catechins) were not degraded after irradiation. The major radiolysis products were identified by NMR and LC-MS and we concluded that flavonols were essentially transformed into depsides. We proposed a reactivity mechanism between flavonols and HER. In a first step, H-transfer occurred from the 3-OH group to HER. Afterwards, C-ring opening occurred due to the presence of the 2,3-double bond in flavonols. Finally, we calculated the reaction constants in order to evaluate the antioxidant activity of flavonols against HER and to compare it with reference compounds.
Marfak
Abdelghafour
A
UPRES EA 1085, Biomolécules et Cibles Cellulaires Tumorales Laboratoire de Biophysique, Faculté de Pharmacie, Equipe Biomolecules 2 rue du Dr. Marcland, 87025 Limoges Cedex, France.
Trouillas
Patrick
P
Allais
Daovy P
DP
Calliste
Claude A
CA
Cook-Moreau
Jeanne
J
Duroux
Jean-Luc
JL
D002392:Catechin / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol / Q000737:chemistry*; D044950:Flavanones / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry*; D044948:Flavonols / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry; D015394:Molecular Structure; D011675:Pulse Radiolysis; D013053:Spectrophotometry
D044950:Flavanones; D005419:Flavonoids; D044948:Flavonols; C065424:1-hydroxyethyl radical; D000431:Ethanol; D002392:Catechin