Dynamic metabolic profile of Zhi-Zi-Da-Huang decoction in rat urine based on hybrid liquid chromatography–mass spectrometry coupled with solid phase extraction

Zhi-Zi-Da-Huang decoction (ZZDHD) has been used for treatment of alcoholic liver disease in China for thousands of years. In order to reveal the dynamic biotransformation of the decoction in vivo, a high-throughout, sensitive and special method based on high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry (HPLC–DAD–TOF/MS) and high performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC–QqQ/MS) was developed and validated. 25 parent compounds and 28 metabolites were characterized, among which, two metabolites were found for the first time and tentatively identified by neutral-loss scan and product-ion scan. All the compounds were assigned to iridoids, flavones, anthraquinones, coumarin or p-coumaric acid, and their biotransformation pathways were found to involve glucuronidation, sulfation, reduction and ring cleavage. Glucuronidation occurred as a major metabolic pathway of genipin and flavanone and the conjugates could be detected almost during the whole sampling duration. To compounds such as anthraquinones, coumarin and p-coumaric acid, sulfation is the only transformation pathway and the metabolites were found at 0–12, 4–18, 4–48 h respectively after administration. Reduction and/or ring cleavage of genipin glucuronide and naringin were also observed obviously. The phenomena that parts of parent compounds and metabolites were able to be detected even 48 h after administration implied that the accumulating effect of these constituents in vivo would happen and the potential toxicity of the decoction might appear if multiple dosing is adopted. The strategy used in this paper was proved helpful to offer important information for the clinical safe use of ZZDHD.