The main enzyme responsible for activation of xenobiotics is
Cytochrome P450 (CYP) enzymes in extrahepatic tissues often play a dominant role in target tissue metabolic activation of xenobiotic compounds. They may also determine drug efficacy and influence the tissue burden of foreign chemicals or bioavailability of therapeutic agents.
Enzymes
Cytochrome P - 450
Glutathione S - transferase
NADPH cytochrome P - 450 reductase
Glucoronyl transferase
Cytochrome P - 450