Differential regulation of detoxification enzymes in hepatic and mammary tissue by hops (Humulus lupulus) in vitro and in vivo

Mol Nutr Food Res. 2013 Jun;57(6):1055-66. doi: 10.1002/mnfr.201200534. Epub 2013 Mar 20.


Scope: Hops contain the phytoestrogen, 8-prenylnaringenin, and the cytoprotective compound, xanthohumol (XH). XH induces the detoxification enzyme, NAD(P)H-quinone oxidoreductase (NQO1) in vitro; however, the tissue distribution of XH and 8-prenylnaringenin and their tissue-specific activity have not been analyzed.

Methods and results: An orally administered hop extract and subcutaneously injected XH were administered to Sprague-Dawley rats over 4 days. LC-MS-MS analysis of plasma, liver, and mammary gland revealed that XH accumulated in liver and mammary glands. Compared with the low level in the original extract, 8-prenylnaringenin was enriched in the tissues. Hops and XH-induced NQO1 in the liver, while only hops reduced NQO1 activity in the mammary gland. Mechanistic studies revealed that hops modulated NQO1 through three mechanisms. In liver cells, (i) XH modified Kelch-like ECH-associated protein leading to nuclear factor (erythroid-derived 2)-like 2 (Nrf2) translocation and antioxidant response element (ARE) activation; (ii) hop-mediated ARE induction was partially mediated through phosphorylation of Nrf2 by PKC; (iii) in breast cells, 8-prenylnaringenin reduced NQO1 likely through binding to estrogen receptorα, recruiting Nrf2, and downregulating ARE-regulated genes.

Conclusion: XH and 8-prenylnaringenin in dietary hops are bioavailable to the target tissues. While hops and XH might be cytoprotective in the liver, 8-prenylnaringenin seems responsible for hop-mediated NQO1 reduction in the mammary gland.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antioxidant Response Elements / drug effects
  • Antioxidant Response Elements / genetics
  • Female
  • Flavanones / blood
  • Flavanones / pharmacokinetics*
  • Flavonoids / blood
  • Flavonoids / pharmacokinetics
  • Flavonoids / pharmacology*
  • Glutathione Transferase / metabolism
  • Humans
  • Humulus / chemistry*
  • Inactivation, Metabolic*
  • Liver / drug effects
  • Liver / enzymology*
  • MCF-7 Cells / drug effects
  • Mammary Glands, Animal / drug effects
  • Mammary Glands, Animal / enzymology*
  • NAD(P)H Dehydrogenase (Quinone) / genetics
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / metabolism
  • Phosphorylation / drug effects
  • Plant Extracts / pharmacokinetics
  • Plant Extracts / pharmacology*
  • Propiophenones / blood
  • Propiophenones / pharmacokinetics
  • Propiophenones / pharmacology*
  • Protein Kinase C / metabolism
  • Protein Transport / drug effects
  • Rats
  • Rats, Sprague-Dawley
  • Tissue Distribution


  • 8-prenylnaringenin
  • Flavanones
  • Flavonoids
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, rat
  • Plant Extracts
  • Propiophenones
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, rat
  • Glutathione Transferase
  • Protein Kinase C
  • xanthohumol