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Peroxynitrite oxidises catechols to o-quinones
1Antioxidant Research Centre, Guy's, King's College and St. Thomas's School of Biomedical Sciences, London, UK.
FEBS Letters
|November 21, 1998
Summary
Caffeic acid, unlike other hydroxycinnamates, does not undergo nitration with peroxynitrite. Instead, it forms a novel o-quinone oxidation product, identified using thiol compounds and alkaline solutions.
Area of Science:
- Biochemistry
- Organic Chemistry
- Chemical Biology
Background:
- Nitration is a common reaction of phenolic compounds with peroxynitrite.
- Monophenolic hydroxycinnamates readily undergo nitration.
- Catechol-containing hydroxycinnamates, like caffeic acid, do not typically undergo nitration.
Purpose of the Study:
- To investigate the chemical interaction mechanism between caffeic acid and peroxynitrite.
- To characterize the reaction products of caffeic acid with peroxynitrite.
- To understand the unique reactivity of caffeic acid.
Main Methods:
- Reaction of caffeic acid with peroxynitrite.
- Characterization of reaction products using nucleophilic thiol compounds (glutathione, L-cysteine).
- Oxidation of caffeic acid in alkaline solutions for product identification.
Main Results:
- Nitration did not occur with caffeic acid.
- A novel compound was detected and characterized as caffeic acid o-quinone.
- The o-quinone product was confirmed through reactions with thiols and alkaline oxidation.
Conclusions:
- Caffeic acid's catechol structure prevents nitration by peroxynitrite.
- Caffeic acid undergoes oxidation to form an o-quinone in the presence of peroxynitrite.
- The identified o-quinone is a key oxidation product of caffeic acid.