Biotransformation

Biotransformation is the chemical alteration (or modifications) of a chemical substance produced by an organism. When this alteration results in mineral compounds, then mineralisation is called biotransformation. Biotransformation involves structural modifications of molecules in the body such as foods, amino acids, toxins, and medications. Rendering non-polar compounds polar is also required so that they are not reabsorbed into renal tubules and are excreted. Toxicokinetics can be regulated by biotransformation of xenobiotics, and the metabolites can hit higher levels in species than their parent compounds. Biotransformation includes two phases: Phase I involving mainly the P-450 (CYP) family, and Phase II catalyzed by conjugation enzymes such as glutathione S-transferase (GST), UDP-glucuronosyltransferase (UGT), and N-acetyltransferase (NAT). Biotransformation of organic xenobiotics normally occurs in the first phase of oxidation (phase I), which introduces a reactive group in the xenobiotic, and a second phase of conjugation (phase II) with a non-toxic endogenous metabolite which produces an excretable product. Phase I of biotransformation is mediated by monooxygenases (CYP), dependent on inducible cytochrome P450. In fact, various types of CYP, formed by different genes, are directly responsible for the degradation of certain chemical family. Phase I and Phase II enzyme synthesis involved in the metabolism of detoxification is inducted by the presence of chemical contaminants in the system. It can be used as a biological tool to track chemical emissions, and biomarkers are known to be the inductive molecules.