Glucuronidation consists of transfer of the
glucuronic acid component of
uridine diphosphate glucuronic acid to a substrate by any of several types of
UDP-glucuronosyltransferase. UDP-glucuronic acid (glucuronic acid linked via a
glycosidic bond to
uridine diphosphate) is an intermediate in the process and is formed in the
liver. One example is the N-glucuronidation of an
aromatic amine,
4-aminobiphenyl, by UGT1A4 or UGT1A9 from human, rat, or mouse liver. : The substances resulting from glucuronidation are known as
glucuronides (or glucuronosides) and are typically much more
water-
soluble than the non-glucuronic acid-containing substances from which they were originally synthesised. The human body uses glucuronidation to make a large variety of substances more water-soluble, and, in this way, allow for their subsequent elimination from the body through urine or feces (via bile from the liver).
Hormones are glucuronidated to allow for easier transport around the body. Pharmacologists have linked drugs to glucuronic acid to allow for more effective delivery of a broad range of potential therapeutics. Sometimes toxic substances are also less toxic after glucuronidation. The conjugation of xenobiotic molecules with
hydrophilic molecular species such as glucuronic acid is known as
phase II metabolism. ==Sites==