Rapid discovery and identification of the prototypes and their metabolites of Da-Huang-Xiao-Shi decoction in rat plasma by an integrative strategy based on liquid chromatography coupled with mass spectrometry.

Da-Huang-Xiao-Shi decoction has been used to treat damp-heat jaundice for centuries in China. However, the absorbed components of the decoction and their related metabolites are little known until now. In this work, an integrative strategy based on liquid chromatography coupled with mass spectrometry (time-of-flight/triple-quadruple tandem) was adopted to effectively identify the prototypes and their metabolites and to speculate the possible transformation pathways among these compounds. Using pattern recognition approaches, the exogenous compounds in rat plasma were screened out from endogenous compounds and then distinguished into prototypes and metabolites according to the characteristic information from the self-building database of Da-Huang-Xiao-Shi decoction. On this basis, the metabolic profiles of main prototypes (such as iridoid glycosides, alkaloids, and anthraquinones) were proposed. As a result, a total of 62 related prototypes and their metabolites were detected and tentatively identified in rat plasma after administration, and among them, three prototypes were found for the first time. Glucuronidation and sulfation were deduced to be the main metabolic pathways of alkaloids, iridoid glycosides, and anthraquinones. The integrative strategy used in this study was an effective approach to rapidly discover and characterize the prototypes and their metabolites from a complex bio-sample without the use of standard substances.