Abstract
Da-Cheng-Qi decoction (DCQD) is a purgative prescription used in China and East Asia. To profile the constituents of this complex traditional Chinese medicine (TCM), a high-performance liquid chromatographic, electrospray ionization, tandem mass spectrometric (HPLC-ESI/MS/MS) analytical method was developed. After separation on a reversed-phase C18 analytical column using gradient elution, samples were analyzed by ESI-MS/MS in negative mode. As a result, a total of 37 compounds were detected, of which two tannins, three anthraquinones, two sennosides, five flavonoids and two lignans were unambiguously identified by comparison with standard compounds, and sixteen compounds were either tentatively identified or deduced according to their MS/MS data. The fragmentation pathways of many of the observed compounds, such as the tannins and lignans are reported for the first time. In addition, the identity of each peak in DCQD was explored by comparison with those of its three constituent herbs. The results indicated that tannins, anthraquinones and sennosides in DCQD originated from Radix et Rhizoma Rhei, flavonoids from Fructus Aurantii Immaturus, and lignans from Cortex Magnoliae officinalis. The present study provides an example of chemical constitution profiling in complex TCM systems using LC/MS/MS.