taurodeoxycholate

Taurodeoxycholate, abbreviated TDCA, is a bile salt formed in the liver by conjugating deoxycholic acid with the amino sulfonic acid taurine. This conjugation creates an anionic, highly water-soluble molecule that remains ionized at intestinal pH, enhancing its detergent properties compared with the unconjugated acid.

Biosynthesis and chemistry: In hepatocytes, bile acid-CoA:amino acid N-acyltransferase adds taurine to deoxycholate, producing TDCA which is secreted into bile via canalicular transporters. In the intestine, gut bacteria can deconjugate taurine, and further bacterial metabolism can convert deoxycholate to other secondary bile acids. TDCA thus participates in a dynamic pool of bile salts that cycle between the liver, bile, and gut.

Function in digestion: As a bile salt, TDCA is an amphipathic detergent that emulsifies dietary fats and forms micelles, increasing the solubility and absorption of lipids and fat-soluble vitamins. Bile salts also influence cholesterol metabolism and can act as signaling molecules that modulate metabolic pathways through receptors such as FXR.

Clinical and research relevance: TDCA is present in human bile, with concentrations influenced by diet, gut microbiota, and liver function. Abnormal bile acid profiles, including altered levels of TDCA, can indicate hepatic or biliary disorders. In research, TDCA is used to study bile acid transport, signaling, and the physicochemical properties of micelle formation.