1H and 13C NMR spectral assignments for low-concentration bile acids in biological samples

Bile acids are the main body of enterohepatic circulation in vivo. They have essential functions such as emulsifying fat, bacteriostasis and regulating multiple metabolic pathways as signal molecules. However, the assignments of NMR signals for some low-concentration bile acids are still needed. This study combined 1D nuclear magnetic resonance (NMR) and 2D NMR techniques including 1H–1H correlation spectroscopy (COSY), 1H–1H total correlation spectroscopy (TOCSY), 1H J-resolved spectroscopy (J-Res), 1H–13C heteronuclear single quantum coherence spectroscopy (HSQC), and 1H–13C heteronuclear multiple bond correlation spectroscopy (HMBC) to assign the 1H and 13C signals of six bile acids in aqueous solution at physiological pH (pH∼7.4) and nine bile acids in methanol. These data are of importance to the NMR-based studies on lipid digestion, absorption, and metabolism.