Quercetin derivatives are deconjugated and converted to hydroxyphenylacetic acids but not methylated by human fecal flora in vitro

A. M. Aura, K. A. O'Leary, G. Williamson, M. Ojala, M. Bailey, R. Puupponen-Pimiä, A. M. Nuutila, K. M. Oksman-Caldentey, K. Poutanen

Research output: Contribution to journalArticleResearchpeer-review

270 Citations (Scopus)


By using a batch in vitro anaerobic fecal fermentation model, we have shown that the fecal microflora can rapidly deconjugate rutin, isoquercitrin, and a mixture of quercetin glucuronides. High levels of β,D-glucosidase, α,L-rhamnosidase, and β,D-glucuronidase were present. Rutin underwent deglycosylation, ring fission, and dehydroxylation. The main metabolite, 3,4-dihydroxyphenylacetic acid, appeared rapidly (2 h) and was dehydroxylated to 3-hydroxyphenylacetic acid within 8 h. The pattern of in vitro fermentation of rutin was not changed by changing the pH (6.0 or 6.9), fermentation scale(10 or 1000 mL), or donors of the inoculum. Hydroxyphenylacetic acids were not methylated by colon flora in vitro. The colonic microflora has enormous potential to transform flavonoids into lower molecular weight phenolics, and these might have protective biological activities in the colon. The site of absorption of flavonoids and the form in which they are absorbed are critical for determining their metabolic pathway and consequent biological activities in vivo.

Original languageEnglish
Pages (from-to)1725-1730
Number of pages6
JournalJournal of Agricultural and Food Chemistry
Issue number6
Publication statusPublished - 13 Mar 2002
Externally publishedYes


  • Deconjugation
  • Dehydroxylation
  • Isoquercitrin
  • Metabolism
  • Quercetin glucuronides
  • Ring fission
  • Rutin

Cite this