Identification of the absorptive constituents and their metabolites in vivo of Puerariae Lobatae Radix decoction orally administered in WZS-miniature pigs by HPLC-ESI-Q-TOFMS

Abstract

In this study, the technique of high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOFMS) was used to analyze and identify the absorptive constituents and their metabolites in drug-containing urine of Wuzhishan (WZS)-miniature pigs administered with Puerariae Lobatae Radix (PLR) decoction. With the accurate mass measurements (<5 ppm) and effective MS(2) fragment ions, 96 compounds, including eight original constituents and 88 metabolites, were identified from the drug-containing urine. Among these, 64 metabolites were new ones and their structures can be categorized into five types: isoflavones, puerols, O-desmethylangolensins, equols and isoflavanones. In particular, puerol-type constituents in PLR were first proved to be absorptive in vivo. Meanwhile, the metabolic pathways of PLR in vivo were investigated. On the basis of relative content of the identified compounds, 13 major metabolites accounting for approximately 50% of the contents, as well as their corresponding 12 prototype compounds, were determined as the major original absorptive constituents and metabolites of PLR in vivo. The HPLC-ESI-Q-TOFMS technique proved to be powerful for characterizing the chemical constituents from the complicated traditional Chinese medicine matrices in this research.

Keywords: HPLC-ESI-Q-TOFMS; Puerariae Lobatae Radix; WZS-miniature pig; absorptive constituents; metabolites.