[Bile acid derivatives-focused chemical profiling in snake bile]

As a precious traditional Chinese medicine(TCM), snake bile has been widely used in numerous Chinese medicine prescriptions. Bile acid(BA) derivatives have been demonstrated as the primary chemical family in snake bile. In-depth chemical characterization of BAs is of great importance towards the establishment of quality standards and clarification of the effective material basis for snake bile. This study firstly employed ~1H-NMR to preliminarily analyze the chemical profiles of snake bile, an automated fraction collector was subsequently implemented to obtain the fractions-of-interest. The fraction was then concentrated and re-analyzed by LC-MS. Based on ~1H-NMR, BAs were found to be the main components of snake bile, and six BAs including CDCA, CA, TCDCA, TCA, TDCA and GCA were tentatively identified from the representative spectrum with the assistance of literature and reference compounds. Whereas the content of TCA in snake bile was too great, resulting in a great obstacle for the detection of trace components, the automated fraction collector was subsequently implemented to obtain the fractions-of-interest for LC-MS analysis. According to matching MS/MS information and retention time with reference compounds as well as database retrieval, a total of 57 BAs were detected and annotated. Because of the combination of ~1H-NMR and LC-MS platforms, the findings are beneficial for the in-depth characterization of BAs in snake bile, which provides references for the establishment of quality control and evaluation methods of snake bile.