Analysis of the fingerprint profile of bioactive constituents of traditional Chinese medicinal materials derived from animal bile using the HPLC–ELSD and chemometric methods: An application of a reference scaleplate

Abstract Traditional Chinese medicinal materials derived from animal bile are widely applied in clinical therapy for thousands of years in several Southeast Asian countries. Although the constituents are similar, these crude drugs exhibit different pharmacological activities; bile acids are the main bioactive constituent. Depending on the source, the price of these crude drugs differs significantly. Therefore, a reliable fingerprint method is needed to analyze and distinguish these crude drugs with a similar composition. In this milieu, we aimed to establish a fingerprint chromatography method that can separate and detect several bile acids simultaneously. A high-performance liquid chromatography separation method was established with evaporative light scattering detection to detect the analytes. The main bioactive constituents of pig bile, cattle bile, sheep bile, bear bile, and three types of cow bezoar were analyzed using the proposed method. The fingerprint chromatography profile of 35 samples were obtained and analyzed using chemometric methods. Considering the differences among samples, a reference scaleplate method was used in the peak alignment procedure. Unsupervised methods (hierarchical cluster analysis and principle component analysis) and supervised methods (K-nearest neighbor, partial least squares discriminant analysis, support vector machine discriminant analysis, and soft independent modeling of class analogy) were used in the chemometric analysis. The results indicated that the fingerprint chromatograms of the seven crude drugs had fingerprint specificity and that they can be well distinguished. In addition, the reference scaleplate method using the chromatogram of a mixed standard solution is practically applicable for peak alignment in the analysis of samples with a large difference in chromatographic peaks. Overall, 17 bile acids can be separated and detected simultaneously using this method and some frequently used TCMMs derived from animal bile can be distinguished accurately.