Methylation of quercetin and fisetin, flavonoids widely distributed in edible vegetables, fruits and wine, by human liver

C. De Santi, A. Pietrabissa, F. Mosca, G. M. Pacifici

Research output: Contribution to journalArticlepeer-review

Abstract

The aim of this investigation was to study the methylation of quercetin and fisetin, 2 chemically related flavonoids, in human liver and to this purpose, an assay was set-up to measure the rates of quercetin and fisetin methylation in human liver. The methylation rates (pmol/min/mg) of quercetin and fisetin were measured in 10 liver samples and the mean ± SD and the median were 170 ± 30 and 177 (quercetin) and 183 ± 15 and 178 (fisetin). The rates of quercetin and fisetin methylation were not different (p = 0.283). The fold of variation among samples was 2 (quercetin) and 1.3 (fisetin). Methyltransferase towards quercetin and fisetin followed Michaelis-Menten kinetics, and the Km values were 2.6 ± 0.3 (quercetin) and 8.6 ± 0.7 μM (fisetin, p = 0.009) and the Vmax values were 187 ± 20 (quercetin) and 276 ± 33 pmol/min/mg (fisetin, p = 0.009). Two, 4 and 8 μl of red Chianti wine added to the incubation mixture reduced the rate of quercetin methylation to 75 ± 4%, 65 ± 9% and 59 ± 9%, respectively, and that of fisetin methylation to 62 ± 3%, 51 ± 3% and 44 ± 4%, respectively. In conclusion, quercetin and fisetin are methylated in human liver and their rates of methylation have a limited variation among subjects.

Original languageEnglish
Pages (from-to)207-212
Number of pages6
JournalInternational Journal of Clinical Pharmacology and Therapeutics
Volume40
Issue number5
Publication statusPublished - 2002

Keywords

  • Fisetin
  • Flavonoids
  • Human liver
  • Methylation
  • Quercetin

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology (medical)

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