Effects of flavonoids and vitamin C on oxidative DNA damage to human lymphocytes

Am J Clin Nutr. 1998 Jun;67(6):1210-8. doi: 10.1093/ajcn/67.6.1210.


This study assessed the antioxidant potencies of several widespread dietary flavonoids across a range of concentrations and compared with vitamin C as a positive control. The antioxidant effects of pretreatment with flavonoids and vitamin C, at standardized concentrations (7.6, 23.2, 93, and 279.4 micromol/L), on oxygen radical-generated DNA damage from hydrogen peroxide (100 micromol/L) in human lymphocytes were examined by using the single-cell gel electrophoresis assay (comet assay). Pretreatment with all flavonoids and vitamin C produced dose-dependent reductions in oxidative DNA damage. At a concentration of 279 micromol/L, they were ranked in decreasing order of potency as follows: luteolin (9% of damage from unopposed hydrogen peroxide), myricetin (10%), quercetin (22%), kaempferol (32%), quercitrin (quercetin-3-L-rhamnoside) (45%), apigenin (59%), quercetin-3-glucoside (62%), rutin (quercetin-3-beta-D-rutinoside) (82%), and vitamin C (78%). The protective effect of vitamin C against DNA damage at this concentration was significantly less than that of all the flavonoids except apigenin, quercetin-3-glucoside, and rutin. The ranking was similar with estimated ED50 (concentration to produce 50% protection) values. The protective effect of quercetin and vitamin C at a concentration of 23.2 micromol/L was found to be additive (quercetin: 71% of maximal DNA damage from unopposed hydrogen peroxide; vitamin C: 83%; both in combination: 62%). These data suggest that the free flavonoids are more protective than the conjugated flavonoids (eg, quercetin compared with its conjugate quercetin-3-glucoside, P < 0.001). Data are also consistent with the hypothesis that antioxidant activity of free flavonoids is related to the number and position of hydroxyl groups.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antioxidants / classification
  • Antioxidants / pharmacology*
  • Ascorbic Acid / pharmacology*
  • DNA Damage / drug effects*
  • Diet
  • Dose-Response Relationship, Drug
  • Electrophoresis
  • Flavonoids / pharmacology*
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Kaempferols*
  • Lymphocytes / drug effects*
  • Lymphocytes / metabolism
  • Male
  • Quercetin / administration & dosage
  • Quercetin / analogs & derivatives
  • Quercetin / pharmacology


  • Antioxidants
  • Flavonoids
  • Kaempferols
  • kaempferol
  • Quercetin
  • Hydrogen Peroxide
  • Ascorbic Acid