glukuronihapon

Glukuronihapon, known in English as glucuronic acid, is a carboxylic sugar acid derived from glucose. It is a hexuronic acid that, at physiological pH, exists mainly as its uronate form (glucuronate). In human biology it is an essential building block for glycosaminoglycans such as hyaluronic acid, as well as for the structural units of proteoglycans in connective tissues.

A central role of glucuronic acid is in detoxification. The body converts many lipophilic substances into more water-soluble forms through a process called glucuronidation, which attaches glucuronyl groups to substrates. This reaction is catalyzed by a family of enzymes known as UDP-glucuronosyltransferases (UGTs). The glucuronide conjugates of bilirubin, steroids, drugs, and various xenobiotics are typically excreted in bile or urine. The activated sugar donor for these reactions is UDP-glucuronic acid, produced from UDP-glucose by the enzyme UDP-glucose dehydrogenase.

Biosynthesis and occurrence extend beyond humans. In plants, glucuronides are common conjugates of phenolic compounds and hormones, aiding storage, transport, and detoxification. Free glucuronic acid can be released during tissue turnover, contributing to the pool of circulating uronates.

Clinical relevance is linked to the efficiency of glucuronidation. Defects in UGT enzymes can lead to impaired bilirubin conjugation, contributing to conditions such as Gilbert syndrome or more severe Crigler-Najjar disease. Because glucuronidation affects the pharmacokinetics of many drugs, genetic or drug-induced variations in UGT activity influence drug metabolism and potential interactions.