Antagonism of aryl hydrocarbon receptor signaling by 6,2′,4′- trimethoxyflavone

Iain A. Murray, Colin A. Flaveny, Brett C. DiNatale, Chris R. Chairo, Jennifer C. Schroeder, Ann Kusnadi, Gary H. Perdew

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


The aryl hydrocarbon receptor (AHR) is regarded as an important homeostatic transcriptional regulator within physiological and pathophysiological processes, including xenobiotic metabolism, endocrine function, immunity, and cancer. Agonist activation of the AHR is considered deleterious based on toxicological evidence obtained with environmental pollutants, which mediate toxic effects through AHR. However, a multitude of plant-derived constituents, e.g., polyphenols that exhibit beneficial properties, have also been described as ligands for the AHR. It is conceivable that some of the positive aspects of such compounds can be attributed to suppression of AHR activity through antagonism. Therefore, we conducted a dioxin response element reporter-based screen to assess the AHR activity associated with a range of flavonoid compounds. Our screen identified two flavonoids (5-methoxyflavone and 7,4′-dimethoxyisoflavone) with previously unidentified AHR agonist potential. In addition, we have identified and characterized 6,2′,4′-trimethoxyflavone (TMF) as an AHR ligand that possesses the characteristics of an antagonist having the capacity to compete with agonists, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[a]pyrene, thus effectively inhibiting AHR-mediated transactivation of a heterologous reporter and endogenous targets, e.g., CYP1A1, independent of cell lineage or species. Furthermore, TMF displays superior action by virtue of having no partial agonist activity, in contrast to other documented antagonists, e.g., α-napthoflavone, which are partial weak agonists. TMF also exhibits no species or promoter dependence with regard to AHR antagonism. TMF therefore represents an improved tool allowing for more precise dissection of AHR function in the absence of any conflicting agonist activity.

Original languageEnglish (US)
Pages (from-to)135-144
Number of pages10
JournalJournal of Pharmacology and Experimental Therapeutics
Issue number1
StatePublished - Jan 2010

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Pharmacology


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