Comprehensive quality evaluation strategy based on non-targeted, targeted and bioactive analyses for traditional Chinese medicine: Tianmeng oral liquid as a case study

Traditional Chinese medicine (TCM), especially herbal medicine compound preparation, faces great challenges in its quality control due to a myriad of components involved. How to perform quality control of TCM more effectively has been a research topic. In this study, we used Tianmeng oral liquid (TOL) as a case study and developed a comprehensive strategy based on non-targeted, targeted and bioactive analyses for quality evaluation of TOL from different batches. Firstly, a non-targeted fingerprinting analysis was performed by HPLC-DAD and UHPLC-MS/MS. Twenty-five batches of TOL were clearly discriminated by similarity analysis and hierarchical cluster analysis and components were tentatively identified. Secondly, the targeted quantitative methods based on HPLC-DAD and HPLC-MS were applied to simultaneous quantitative determination of five and eight marker compounds, especially toxic component strychnine, respectively. The quantitative data were processed with principal component analysis for differentiating different batches of samples. Finally, we explored the feasibility of establishing a total antioxidant capacity (TAC) model. How to use the peak area instead of the corresponding concentration to determine the antioxidant activity-related compounds was theoretically explained for the first time, which was of great significance for the study of the fingerprint-efficacy relationship. The orthogonal signal correction-partial least squares model was employed to predict the TAC of TOL from their chromatographic fingerprints and identify three potential antioxidant markers. These results demonstrated that the comprehensive strategy from fingerprinting, chemical composition, multiple-component quantification, and antioxidant activity could be applied to quality evaluation of TOL and discrimination of the expired and unexpired samples.