Dglucuronic

D-glucuronic acid, also called D-glucuronate, is a six-carbon uronic acid derived from D-glucose by oxidation of the terminal primary alcohol to a carboxyl group. It exists in free form in small quantities and, more importantly, as a component of the glycosaminoglycans that form part of the extracellular matrix, such as hyaluronic acid, chondroitin sulfate, dermatan sulfate, and heparan sulfate.

In mammals, the principal metabolic pathway converts UDP-glucose to UDP-glucuronic acid via UDP-glucose dehydrogenase. UDP-glucuronic acid serves as the activated donor (UDP-glucuronosyl) in glucuronidation reactions catalyzed by uridine diphosphate-glucuronosyltransferases (UGTs). Through these reactions, a glucuronic acid moiety is attached to a wide range of substrates, including bilirubin, steroid hormones, and xenobiotics, increasing water solubility and promoting excretion in bile or urine.

Glucuronidation is a major detoxification mechanism. Free D-glucuronic acid itself participates in the formation of glycosaminoglycans in connective tissues, and its conjugation products (glucuronides) may be deconjugated by intestinal beta-glucuronidases, enabling enterohepatic recirculation of certain compounds.

In clinical terms, defects in bilirubin glucuronidation—due to UGT enzyme deficiencies or regulatory abnormalities—underlie conditions such as Crigler-Najjar syndrome and Gilbert's syndrome, characterized by elevated unconjugated bilirubin. The study of D-glucuronic acid and glucuronidation has implications for drug safety, liver function, and toxicology.

D-glucuronic acid occurs widely in organisms, forming GAGs in animals and contributing to plant and bacterial polysaccharides. It is also utilized industrially as a component in certain biopolymers and as a precursor in the synthesis of some dyes and pharmaceutical agents.