The Flow of the Redox Energy in Quercetin during Its Antioxidant Activity in Water

Zhengwen Li*, Mohamed Moalin*, Ming Zhang*, Lily Vervoort*, Erik Hursel*, Alex Mommers*, Guido R. M. M. Haenen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Web of Science)

Abstract

Most studies on the antioxidant activity of flavonoids like Quercetin (Q) do not consider that it comprises a series of sequential reactions. Therefore, the present study examines how the redox energy flows through the molecule during Q's antioxidant activity, by combining experimental data with quantum calculations. It appears that several main pathways are possible. Pivotal are subsequently: deprotonation of the 7-OH group; intramolecular hydrogen transfer from the 3-OH group to the 4-Oxygen atom; electron transfer leading to two conformers of the Q radical; deprotonation of the OH groups in the B-ring, leading to three different deprotonated Q radicals; and finally electron transfer of each deprotonated Q radical to form the corresponding quercetin quinones. The quinone in which the carbonyl groups are the most separated has the lowest energy content, and is the most abundant quinone. The pathways are also intertwined. The calculations show that Q can pick up redox energy at various sites of the molecule which explains Q's ability to scavenge all sorts of reactive oxidizing species. In the described pathways, Q picked up, e.g., two hydroxyl radicals, which can be processed and softened by forming quercetin quinone.

Original languageEnglish
Article number6015
Number of pages16
JournalInternational journal of molecular sciences
Volume21
Issue number17
DOIs
Publication statusPublished - 21 Aug 2020

Keywords

  • flavonoid
  • quercetin
  • redox modulation
  • antioxidant
  • molecular mechanism
  • electron transfer
  • proton transfer
  • COUPLED ELECTRON-TRANSFER
  • DISSOCIATION-CONSTANTS
  • GAS-PHASE
  • FLAVONOIDS
  • PROTON
  • THERMOCHEMISTRY
  • 4'O-METHYLQUERCETIN
  • METABOLITES
  • MECHANISMS
  • ASCORBATE

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