Radical-capturing reaction of 5,7,3',4'-tetramethylquercetin with the AIBN [2,2'-azobis-isobutyronitrile] radical initiator

In order to clarify the mechanism for the radical-capturing reaction which is initiated at the C3-hydroxyl group of flavonols, 5,7,3',4'-tetramethylquercetin (TMQ) was reacted with the 2,2'-azobis-isobutyronitrile (AIBN) radical initiator in benzene. Six products, one depside and its...

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Bibliographic Details
Published in:Bioscience, biotechnology, and biochemistry biotechnology, and biochemistry, 2000-01, Vol.64 (1), p.173-177
Main Authors: Ishikawa, T. (Gifu Univ. (Japan). Faculty of Agriculture), Takagi, M, Kanou, M, Kawai, S, Ohashi, H
Format: Article
Language:English
Subjects:
2,2'-azobis-isobutyronitrile (AIBN)
ANTIOXIDANTES
ANTIOXIDANTS
antioxidative activity
ANTIOXYDANT
Benzene
Chromatography, High Pressure Liquid
Free Radicals
Hydrolysis
Models, Chemical
Nitriles
QUERCETIN
Quercetin - analogs & derivatives
Quercetin - chemistry
QUERCETINA
QUERCETINE
radical-capturing ability
reaction mechanism
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Summary:In order to clarify the mechanism for the radical-capturing reaction which is initiated at the C3-hydroxyl group of flavonols, 5,7,3',4'-tetramethylquercetin (TMQ) was reacted with the 2,2'-azobis-isobutyronitrile (AIBN) radical initiator in benzene. Six products, one depside and its two hydrolytic products, one nitrile adduct, and two others, were isolated from the reaction mixture, and their structures were determined by instrumental analyses. The quantitative change to the four main products against the reaction time was measured by an HPLC method. The radical-capturing reaction pathway for TMQ with AIBN is proposed from these products and their quantitative changes. The pathway dividing into two clearly reveals that one subpath formed the depside and its hydrolytic products, while the other formed the nitrile adduct. The reactivity of each two subpath was nearly the same, different from the case of TMQ and the 2,2'-azobis-2,4-dimethylvaleronitrile (AMVN) radical initiator
ISSN:0916-8451
1347-6947
DOI:10.1271/bbb.64.173