Offline two-dimensional liquid chromatography-mass spectrometry for comprehensive characterization of chemical constituents and in vivo metabolism of Shiqi Waigan Granules.

OBJECTIVE

To investigate the chemical constituents of Shiqi Waigan Granules and their metabolic distribution in rats.

METHODS

An off-line two-dimensional liquid chromatography-mass spectrometry approach was employed to identify the constituents of Shiqi Waigan Granules. A UPLC-QTOF-MS method was established to analyze the distribution of prototype compounds and metabolites in rat plasma, heart, liver, lung, kidney, spleen and brain after oral administration, and to elucidate the metabolic pathways.

RESULTS

(1) A total of 315 compounds were successfully identified in Shiqi Waigan Granules. Compared with conventional one-dimensional LC, the off-line 2D system amplified trace compounds and resolved more isomers, enabling a more systematic and refined characterization of the chemical profile. (2) Based on plasma pharmacochemistry and Phase I and II metabolic pathways, 66 prototype compounds and 102 metabolites were tentatively identified in rat plasma. (3) Most constituents were detected in liver, kidney, lung and spleen, whereas fewer were found in heart and brain.

CONCLUSION

Shiqi Waigan Granules are mainly composed of flavonoids, terpenoids, organic acids, lignans, phenolics, phenylpropanoids and glycosides. In vivo, these constituents primarily undergo hydrolysis, reduction, hydroxylation, carboxylation, sulfation, glucuronidation and composite reactions, and are widely distributed as either prototype compounds or their Phase I/II metabolites.