Single-step analysis of individual conjugated bile acids in human bile using 1H NMR spectroscopy

H-1 and C-13 NMR spectra of intact human bile were assigned using one-dimensional (H-1 and C-13) and two-dimensional (H-1-H-1 and H-1-C-13) experiments. Individual conjugated bile acids-glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid, and taurochenodeoxycholic acid-were identified. The bile acids were quantified accurately and individually in a single step by using distinct and characteristic amide signals. Making use of C-13 NMR, the study also suggests a way to analyze unconjugated bile acids separately, if present. Chemical shift assignments and rapid single-step analysis of individual conjugated bile acids from intact bile presented herein may have immense utility in the study of bile acid metabolism and deeper understanding of hepatobiliary diseases.