Induction of drug-metabolizing enzymes by garlic and allyl sulfide compounds via activation of constitutive androstane receptor and nuclear factor E2-related factor 2

Drug Metab Dispos. 2007 Jun;35(6):995-1000. doi: 10.1124/dmd.106.014340. Epub 2007 Mar 12.


Garlic oil (GO) contains several linear sulfur compounds, including diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), that induce drug-metabolizing enzymes such as CYP2B and NAD(P)H quinone oxidoreductase 1 (NQO1). CYP2B and NQO1 are primarily regulated by constitutive androstane receptor (CAR) and nuclear factor E2-related factor 2 (Nrf2) transcription factors, respectively. The purpose of this study was to determine whether GO and its specific constituents induce these two enzymes via CAR and Nrf2 activation. Female Wistar-Kyoto (WKY) rats express little CAR protein and exhibit less induction of CYP2B1/2 than males. GO, DAS, and DADS, but not DATS, induced CYP2B1/2 mRNA levels to a greater extent in WKY males than in females, suggesting CAR activation. Conversely, DAS induced NQO1 levels equally in WKY males and females, indicating CAR-independent induction in rats. DAS, but not GO, DADS, or DATS, induced CYP2B10 mRNA levels 530-fold in wild-type (WT) mice, whereas this induction was attenuated in CAR(-/-) mice. DAS induced NQO1 in WT and CAR(-/-) mice equally, suggesting CAR-independent induction in mice. DAS induced NQO1 5-fold in WT mice, whereas induction was completely absent in Nrf2(-/-) mice, indicating DAS also activates Nrf2. DAS induction of CYP2B10 mRNA was independent of Nrf2 presence or absence. In in vivo transcription assays, DAS activated the human CYP2B6 promoter, and the antioxidant response element of the human NQO1 promoter, respectively. These studies indicate that GO constituents, particularly DAS, activate CAR and Nrf2 to induce drug-metabolizing enzymes.

Publication types

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

MeSH terms

  • Allyl Compounds / pharmacology*
  • Animals
  • Aryl Hydrocarbon Hydroxylases / genetics
  • Cytochrome P-450 CYP2B1 / genetics
  • Cytochrome P-450 CYP2B6
  • Cytochrome P450 Family 2
  • Disulfides / pharmacology
  • Female
  • Herb-Drug Interactions
  • Humans
  • Liver / drug effects*
  • Liver / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • NAD(P)H Dehydrogenase (Quinone) / genetics
  • NADPH Dehydrogenase / genetics
  • NF-E2-Related Factor 2 / deficiency
  • NF-E2-Related Factor 2 / genetics*
  • Oxidoreductases, N-Demethylating / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Wistar
  • Receptors, Cytoplasmic and Nuclear / deficiency
  • Receptors, Cytoplasmic and Nuclear / genetics*
  • Steroid Hydroxylases / genetics
  • Sulfides / pharmacology*
  • Transcription Factors / deficiency
  • Transcription Factors / genetics*


  • Allyl Compounds
  • Disulfides
  • NF-E2-Related Factor 2
  • RNA, Messenger
  • Receptors, Cytoplasmic and Nuclear
  • Sulfides
  • Transcription Factors
  • diallyl trisulfide
  • constitutive androstane receptor
  • diallyl disulfide
  • allyl sulfide
  • Steroid Hydroxylases
  • Aryl Hydrocarbon Hydroxylases
  • CYP2B6 protein, human
  • Cyp2b10 protein, mouse
  • Cytochrome P-450 CYP2B1
  • Cytochrome P-450 CYP2B6
  • Cytochrome P450 Family 2
  • steroid 16-beta-hydroxylase
  • Oxidoreductases, N-Demethylating
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, rat
  • Nqo1 protein, mouse
  • NADPH Dehydrogenase