What is the main site of biotransformation in the human body?
The main site of biotransformation is the liver, where enzymes such as cytochrome P450 enzymes catalyse the conversion of xenobiotics however, especially in the case of xenobiotics absorbed through the lungs, if the dosage is large enough, or the blood liver flow decreases then not all of the xenobiotics in the blood will have been converted, leaving a chance for the xenobiotic to cause adverse effects. There is also the possibility that during biotransformation an intermediate metabolite may be formed with higher toxicity than the original molecule in particularly if the intermediate metabolite reacts with cells. For example, P450 enzymes generally oxidise their species which can increase the possibility of an active oxygen species e.g. a hydroxyl radical being formed, increasing the chance of damage to proteins, lipids and deoxyribonucleic acid in cells, therefore causing illness/damage or death to live organisms.