taurochenodeoxycholic

Taurochenodeoxycholic acid (TCDCA) is a bile acid formed by conjugation of chenodeoxycholic acid (CDCA) with the amino acid taurine in the liver. As a taurine-conjugated bile acid, it is one of the primary constituents of the bile acid pool and participates in fat digestion.

Biosynthesis and metabolism: CDCA is a primary bile acid synthesized from cholesterol in hepatocytes and can be conjugated with either glycine or taurine by bile acid-CoA:amino acid N-acyltransferase (BAAT). The resulting taurochenodeoxycholic acid is secreted into bile, enters the intestinal tract, and facilitates emulsification of lipids. In the intestine, conjugated bile acids can be deconjugated and transformed by gut microbiota, and a portion is reabsorbed via the enterohepatic circulation back to the liver.

Physiological and clinical relevance: Bile acids like TCDCA activate receptors such as FXR and TGR5, influencing bile acid, lipid, and glucose metabolism. They exhibit detergent activity to aid lipid solubilization; however, conjugation with taurine reduces passive diffusion, balancing solubility and toxicity. Altered levels of taurochenodeoxycholic acid can occur in liver disease or cholestasis and may be detected in serum, bile, or feces as part of metabolomic or diagnostic analyses.

Measurement and interpretation: Quantification is typically performed by LC-MS/MS in clinical or research settings. TCDCA is usually reported alongside other bile acids to assess the composition and enterohepatic circulation of the bile acid pool.