Lithocholic acid (3α-hydroxycholanic acid, CAS 434-13-9) is a monohydroxy secondary bile acid. It is a hydrophobic steroid acid derived from the bacterial metabolism of chenodeoxycholic acid in the colon. Its molecular formula is C₂₄H₄₀O₃, and it is characterized by a single hydroxyl group at the 3α position of the cholane skeleton. Primarily, lithocholic acid is a key biomarker and a metabolic intermediate in bile acid research. It has been investigated for its role in various physiological and pathological processes, including its involvement in liver diseases, intestinal inflammation, and as a signaling molecule through receptors like FXR and TGR5. In the pharmaceutical context, it serves as a starting material or intermediate for the synthesis of other bile acid derivatives and potential therapeutic agents targeting digestive system disorders. While lithocholic acid itself is not a widely used therapeutic API due to its hepatotoxicity at high concentrations, its derivatives and analogs are of significant interest in drug development. It is also utilized as a reference standard in analytical chemistry for studying bile acid metabolism and in biochemical research to modulate nuclear receptor pathways.