UDPglukuronihapon

UDP-glucuronic acid, also known as UDP-glucuronate, is a nucleotide sugar that provides the activated form of glucuronic acid used in key biosynthetic and detoxification pathways. In humans it is synthesized in the cytosol from UDP-glucose by the enzyme UDP-glucose dehydrogenase (UGDH) in an NAD+-dependent reaction. The resulting UDP-glucuronic acid serves as a donor substrate for UDP-glucuronosyltransferases (UGTs), which catalyze glucuronidation reactions that attach glucuronic acid to a broad range of lipophilic substances, including drugs, bilirubin, steroids, and xenobiotics. The glucuronide products are more water-soluble and are excreted via urine or bile, facilitating detoxification and elimination.

UDP-glucuronic acid is also a crucial precursor in the biosynthesis of glycosaminoglycans. It contributes to the formation of hyaluronic acid, as well as proteoglycans such as chondroitin sulfate, dermatan sulfate, and heparan sulfate. These polysaccharides are integrated into the extracellular matrix, where they influence tissue hydration, elasticity, and signaling.

Regulation of UDP-glucuronic acid availability links central carbohydrate metabolism with detoxification and extracellular matrix production. Factors affecting the supply of UDP-glucose, NAD+ levels, or UGDH activity can influence both glucuronidation capacity and glycosaminoglycan synthesis. Clinically, variation in UGT enzymes impacts bilirubin glucuronidation and drug metabolism, while deficiencies in UDP-glucuronic acid biosynthesis or its downstream pathways can have broader effects on metabolism and connective tissue formation. Overall, UDP-glucuronic acid is a central donor sugar bridging metabolism, detoxification, and extracellular matrix biology.