This study aimed to establish an analytical method capable of simultaneously quantifying the prototype components of Si-Ni-San and screening their metabolites to elucidate its tissue distribution and metabolic characteristics in an ulcerative colitis (UC) mouse model. To this end, an integrated analysis strategy based on UPLC-QqQ-MS was developed and validated, combining the targeted quantification of 12 prototype components with a pseudo-targeted metabolite screening technique based on ion pair list-triggered data-dependent acquisition. Samples were extracted with 80% methanol (100 mg/mL) and processed with internal standards. Separation was achieved on a Waters Acquity UPLC HSS PFP column using a gradient elution with a mobile phase consisting of acetonitrile and 5 mmol/L ammonium acetate containing 0.1% formic acid. Analysis was performed using an electrospray ionization (ESI) source in multiple reaction monitoring mode. Methodological validation confirmed that all parameters met the requirements for bio-sample analysis. Application of this method revealed that the content of Si-Ni-San prototype components in the colon, liver, and kidneys of UC mice was significantly higher than that in healthy mice. Furthermore, the number of phase II metabolites was markedly greater than that of phase I metabolites in all tested samples. The results demonstrate the reliability of the established method and preliminarily reveal the tissue distribution characteristics of Si-Ni-San under UC conditions and its metabolism pattern dominated by phase II conjugation, which provides a methodological basis and experimental data for further in-depth research into its effective target tissues and pharmacodynamic material basis.

Dysregulation of immune response is currently recognized as one of the important pathological factors in ulcerative colitis (UC). Based on the confirmation that the Sini San (SNS) can significantly improve the colon inflammation induced by dextran sulfate sodium sulfate (DSS) in mice, the present work systematically studied the xenobiotics in the colon and mesenteric lymph nodes, spleen, and thymus of UC mice after administration of SNS by high-performance liquid chromatography-ion trap time-of-flight mass spectrometry (HPLC-IT-TOF-MS). The results showed that, in addition to the colon, some components and their metabolites in SNS could be distributed in immune tissues, and it was found that the quality of relatively low-abundance and weakly responsive components such as saikosaponin a, paeoniflorin, and glycyrrhizic acid had the characteristics of efficient transmission to the colon and lymphoid organs. These components were very likely to be the source of pharmacodynamic substances of SNS. The findings of this study lay a foundation for the study of the efficacy and molecular mechanism of the components against ulcerative colitis, and also provide a scientific basis for the rational clinical application of SNS, which is expected to promote the secondary development of its preparations.