Profiling aromatic constituents of Chimonanthus nitens Oliv. leaf granule using mass spectrometry

Rationale

The chemical constituent of Chinese patent medicine is usually different from crude medicine because of specific preparation process. Chimonanthus nitens Oliv. leaf granule is widely used for prevention against Covid-19 in China. However, none research on chemical constituents of the granule and their variation during the preparation process is reported.

Methods

Fragmentation rules of reference compounds were investigated in electrospray ionization mass spectrometry, new gas phase reaction was rationalized via electronic and steric effect, and calculated chemistry. Then, a strategy based on new fragmentation patterns was conducted to profile aromatic constituents. Additionally, basing on untargeted metabolomics analytical workflow, comparison on chemical constituents of leaf and granule was performed.

Results

New fragmentation patterns related to two competing reactions, ring-opening and ring-closing reaction for coumarin have been proposed and been rationalized intensely. New established diagnostic ion at m/z 81.0331 worked powerfully in assignment of OH-7 and substituent at C-8 of coumarin. McLafferty rearrangement occurring to coumarin glycoside with sugar group at C-4 was firstly observed, and newly formed dialogue ions at m/z 147.0440, 119.0488 and 91.0543.

Conclusions

Aromatic constituents of the granule were firstly profiled. A total of 114 aromatic compounds were identified, of those 85 compounds were firstly discovered. The kaempferol-7-O-neohesperidoside and its homologues were mostly enriched in the granule. Considering their reported bioactivities, these analogues possibly contribute greatly to clinical efficacy. Our present results offered new fragmentation theory for coumarins and new material basis for quality control of the granule.