Review of human UDP-glucuronosyltransferases and their role in drug-drug interactions

The UDP-glycosyltransferases (EC 2.4.21.17) are a group of enzymes that catalyze the transfer of sugars (glucuronic acid, glucose, and xylose) to a variety of acceptor molecules (aglycones). The sugars may be attached at aromatic and aliphatic alcohols, carboxylic acids, thiols, primary, secondary, tertiary, and aromatic amino groups, and acidic carbon atoms. In vivo, the most common reaction occurs by transfer of a glucuronic acid moiety from uridine-diphosphate glucuronic acid (UDPGA) to an acceptor molecule. This process is termed either glucuronosylation or glucuronidation. When the enzymes catalyze this reaction, they are also referred to as VDP-glucuronosyltransferases (VGTs). The structure and function of these enzymes have been the subject of several reviews [1-3]. This chapter will review the role of these enzymes in drug-drug interactions that occur in humans.