Figure 4

The two different models for the contribution of CYP1A1 to chemoprevention. (A) Molecular mechanism of aminoflavone AhR-induced CYP1A1 activation. It must be stressed that this mechanism of action is also likely to apply for certain dietary natural products, such as the flavonoid diosmetin, which induces CYP1A1 expression and is a substrate of the same enzyme [129, 124, 125]. (B) Chemopreventative action of natural products, such as the stilbene resveratrol, is based on the inhibition of benzo[a]pyrene binding to AhR, the binding of the AhR-ARNT-benzo[a]pyrene complex to xenobiotic response elements (XREs), and the inhibition of the formation of CYP1A1-mediated carcinogenic reactive intermediates, notably benzo[a]pyrene-7,8-diol-9,10-epoxide.