OBJECTIVE To conduct qualitative analysis of chemical constituents in the crude extract of Modified Ermiao Formula, along with its blood-absorbed components and metabolites in rats post-administration employing ultra-performance liquid chromatography coupled with quadrupole-exactive orbitrap tandem mass spectrometry (UPLC-Q-Exactive Orbitrap-MS/MS).

METHODS Separation was performed on a Waters HSS T₃ column (100 mm×2.1 mm, 1.8 μm) using gradient elution with 0.1% formic acid in water (mobile phase A) and 0.1% formic acid in acetonitrile (mobile phase B), under controlled conditions: column temperature maintained at 40 ℃, flow rate set to 0.3 mL ·min^-1, and injection volume fixed at 2 μL. Mass spectrometric data acquisition utilized an electrospray ionization (ESI) source with scanning in both positive and negative ion modes.

RESULTS By analyzing precise molecular weights, retention times, and MS/MS fragmentation patterns, and cross-referencing these against established databases and published literature, 173 chemical constituents were definitively identified in the Modified Ermiao Formula crude extract. These primarily comprised flavonoids, organic acids, and alkaloids. Additionally, 32 prototype components and 13 metabolites were characterized in the serum of dosed rats. Organic acids constituted the predominant class of serum prototype components, undergoing in vivo metabolism principally through demethylation and carboxyl glucuronidation.

CONCLUSION This study provides the initial delineation of blood-absorbed prototype components derived from Modified Ermiao Formula, with concomitant identification of their metabolites, thereby establishing a foundational framework for elucidating the pharmacologically active constituents of this formula.