A multistep approach for exploring quality markers of Shengjiang Xiexin decoction by integrating plasma pharmacochemistry-pharmacokinetics-pharmacology

Shengjiang Xiexin decoction (SXD), a well-known traditional Chinese medicine (TCM), was used to alleviate delayed-onset diarrhea induced by the chemotherapeutic agent irinotecan (CPT-11). Our previous study showed that SXD regulated multidrug resistance-associated protein 2 (Mrp-2) to alter the pharmacokinetics of CPT-11 and its metabolites. However, the pharmacodynamic constituents and the related quality markers of SXD are unclear. In this study, ultra -high performance liquid chromatography coupled with quadrupole orbitrap highresolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was utilized to identify the prototypes and metabolites in rat plasma after oral administration of SXD. The pharmacokinetic markers (PK markers) were screened through quantification and semiquantification of SXD-related xenobiotics in plasma using liquid chromatography-mass spectrometry (LC-MS) combined with statistical analysis. Computational molecular docking was performed to assess the potential binding ability of the PK markers with the target Mrp-2. The results were verified by evaluating the impact on Mrp-2 function using Caco-2 cells. The quality markers were chosen from these PK markers based on the binding affinities with Mrp-2, the specificity and the traceability. As a result, a total of 142 SXD-related exogenous components, including 77 prototypes and 65 metabolites, were detected in rat plasma. Among these, 83 xenobiotics were selected as PK markers due to their satisfactory pharmacokinetic behaviors. Based on the characteristics of quality markers, the prototype-based PK markers were considered the indices of quality control for SXD, including baicalin, baicalein, wogonoside, wogonin, liquiritigenin, isoliquiritigenin, norwogonin, oroxylin A, dihydrobaicalin, chrysin, glycyrrhizic acid, glycyrrhetinic acid, oroxylin A 7-O-glucuronide, liquiritin and isoliquiritin. This study provided an interesting strategy for screening the quality markers involved in the pharmacokinetics of SXD and its action target, which offered important information for the modernization of SXD and other TCM formulae.