Glucuronic acid (from Greek γλυκερός - "sweet") is a carboxylic acid that has the structure of a glucose molecule that has had its sixth carbon atom (of six total) oxidized. Its formula is C6H10O7.
The salts of glucuronic acid are known as glucuronates; the anion C6H9O7− is the glucuronate ion.
Glucuronic acid is highly soluble in water. In the animal body, glucuronic acid is often linked to poisonous substances to allow for subsequent elimination, and to hormones to allow for easier transport. Pharmacists also commonly link drugs to glucuronic acid to allow for easier delivery. These linkages involve O-glycosidic bonds. The process is known as glucuronidation, and the resulting substances are known as glucuronides (or glucuronosides).
Glucuronidation uses UDP-glucuronic acid (glucuronic acid linked via a glycosidic bond to uridine diphosphate) as an intermediate. UDP-glucuronic acid is formed in the liver of all animals. The linking of toxins to glucuronic acid is catalyzed by the enzyme UDP-glucuronyltransferase, which has been found in all major body organs: heart, kidneys, adrenal gland, spleen, thymus, etc.
UDP-glucuronic acid also serves as the source of glucuronic acid for the biosynthesis of polysaccharides and is an intermediate in the biosynthesis of ascorbic acid (except in primates and guinea pigs).
Glucuronidases are those enzymes that hydrolyze the glycosidic bond between glucuronic acid and some other compound.
Glucuronic acid should not be confused with gluconic acid, a linear carboxylic acid resulting from the oxidation of a different carbon of glucose.
Glucuronidation is a major inactivating pathway for a huge variety of exogenous and endogenous molecules, including drugs, polluants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids and bile acids. Glucuronidase is an enzyme that inhibits the glucuronidation process, breaking apart the bound toxins. Calcium D-glucarate (a calcium salt that is found in some plants, such as apples, grapefruit, broccoli and alfalfa) suppresses that enzyme, restoring this particular detoxification pathway