Effect of Glucuronidation on the Potential of Kaempferol to Inhibit Serine/Threonine Protein Kinases

Karsten Beekmann*, Laura H.J. De Haan, Lucas Actis-Goretta, Peter J. Van Bladeren, Ivonne M.C.M. Rietjens

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)


To study the effect of metabolic conjugation of flavonoids on the potential to inhibit protein kinase activity, the inhibitory effects of the dietary flavonol kaempferol and its major plasma conjugate kaempferol-3-O-glucuronide on protein kinases were studied. To this end, the inhibition of the phosphorylation activity of recombinant protein kinase A (PKA) and of cell lysate from the hepatocellular carcinoma cell line HepG2 on 141 putative serine/threonine phosphorylation sites derived from human proteins was assessed. Glucuronidation reduced the inhibitory potency of kaempferol on the phosphorylation activity of PKA and HepG2 lysate on average about 16 and 3.5 times, respectively, but did not appear to affect the target selectivity for kinases present in the lysate. The data demonstrate that, upon glucuronidation, kaempferol retains part of its intrinsic kinase inhibition potential, which implies that K3G does not necessarily need to be deconjugated to the aglycone for a potential inhibitory effect on protein kinases.

Original languageEnglish
Pages (from-to)1256-1263
JournalJournal of Agricultural and Food Chemistry
Issue number6
Publication statusPublished - 2016


  • conjugation
  • flavonoid
  • glucuronidation
  • serine/threonine protein kinases
  • substrate microarray


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