The relative antioxidant activities of plant-derived polyphenolic flavonoids

Free Radic Res. 1995 Apr;22(4):375-83. doi: 10.3109/10715769509145649.


The relative antioxidant activities, against radicals generated in the aqueous phase, of a range of plant-derived polyphenolic flavonoids, constituents of fruit, vegetables, tea and wine, have been assessed. The results show that compounds such as quercetin and cyanidin, with 3',4' dihydroxy substituents in the B ring and conjugation between the A and B rings, have antioxidant potentials four times that of Trolox, the vitamin E analogue. Removing the ortho-dihydroxy substitution, as in kaempferol, or the potential for electron delocalisation by reducing the 2,3 double bond in the C ring, as in catechin and epicatechin, decreases the antioxidant activity by more than 50%, but these structures are still more effective than alpha-tocopherol or ascorbate. The relative significance of the positions and extents of hydroxylation of the A and B rings to the total antioxidant activity of these plant polyphenolics is demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthocyanins / chemistry
  • Anthocyanins / metabolism*
  • Antioxidants / metabolism*
  • Chromans / metabolism
  • Flavonoids / chemistry
  • Flavonoids / metabolism*
  • Hydrogen Peroxide / metabolism
  • Isoflavones / metabolism
  • Myoglobin / metabolism
  • Plants
  • Spectrophotometry


  • Anthocyanins
  • Antioxidants
  • Chromans
  • Flavonoids
  • Isoflavones
  • Myoglobin
  • Hydrogen Peroxide
  • 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid