The main enzyme responsible for activation of xenobiotics is: (A) Cytochrome P - 450, (B) Glutathione S - transferase, (C) NADPH cytochrome P - 450 reductase, (D) Glucoronyl transferase
Answer is A. 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.