Derivative multiple reaction monitoring and single herb calibration approach for multiple components quantification of traditional Chinese medicine analogous formulae

Abstract

In comparison with monotherapy in western medicine, traditional Chinese medicine (TCM) advocates combinational therapy for treating diseases and TCM formula is a representative for this approach. Despite of extensive clinical applications of TCM formulae, knowledge about their pharmacological activities, mechanisms of action and cellular targets remains limited. A main contributing factor to these unanswered questions is unavailability of chemical compositions and their contents in the formulae. Several challenges hinder global qualitative and quantitative analysis of the formulae, including large quantities of constituents, potential physicochemical changes during decoction and lack of authentic standards. Herein we introduced an integrated strategy based on liquid chromatography coupled with mass spectrometry (LC-MS) systems to address such challenges. First, liquid chromatography-ion trap and quadrupole time-of-flight mass spectrometry (LC-IT/MS and LC-QTOF/MS) were utilized to characterize chemical profiling of the formulae. Meanwhile, MS(2) of IT/MS produced major parameters for derivative multiple reaction monitoring (DeMRM) on liquid chromatography-triple quadrupole mass spectrometry (LC-TQ/MS), which offered rapid and direct transition design in the quantitative assay. Instead of authentic standards, serial dilutions of single herbs were employed in this study to construct calibration curves necessary for calculating relative concentrations of components. Xiao-Banxia decoction and its four analogous formulae were then taken to exemplify the feasibility of currently proposed methodology. Among the 160 qualitatively identified components, a total of 138 components were semi-quantified for these decoctions. Based on these results, we demonstrated that co-decoction of different herbs could result in concentration variations of components and this effect was more prominent when certain herbs were combined. Our results indicated that the present strategy would significantly contribute to chemical studies on TCM and its utilities could be extended to other research fields, such as metabolomics and comparative chemistry.

Keywords: Analogous formulae; Derivative multiple reaction monitoring; LC-MS; Single herb calibration approach; Xiao-Banxia decoction.