A Fast and Robust HPLC Separation of Bile Acids and Their Conjugates with Ascentis Express C18

Helping to Elucidate the Role of Plasma Bile Acid Signalling in Humans

Introduction

Bile acids are increasingly recognized as playing an important signaling role in the control of immune response and energy metabolism. Recently, there has been interest in measuring bile acid concentrations in plasma and their impact on hormone concentrations, for example as affected by bariatric surgery (Figure 1).

Primary bile acids are synthesized in the liver from cholesterol. The majority are conjugated, increasing hydrophilicity, with either glycine or taurine. They are stored in the gall bladder and released into the small intestine on food consumption. Bacteria in the gut can convert primary bile acids to secondary bile acids which are then reabsorbed and taken back to the liver as part of enterohepatic circulation. Here secondary bile acids can also be glycine or taurine conjugated. Spill-over from this system results in bile acids in the peripheral circulation. There are potentially 15 species which can be measured in a peripheral plasma sample (Figure 2).