Induction of Cytochromes P450

Humans and rodents are exposed to many foreign compounds in their diet (e.g., herbal supplements such as St. John's wart), in their environment (e.g., organ-ochlorine pesticides and polychorinated biphenyls), and as clinically prescribed drugs (e.g., rifampin and phenobarbital). In response to these exposures mammals have evolved mechanisms to induce proteins involved in xenobiotic detoxification. Metabo-lism by Phase I enzymes, particularly the heme containing monooxygenases- cytochromes P450 is frequently the first line of defense against such xenobiotics.