3.2 Global chemical analysis of LJ
The chemical components of herbal medicines are extremely complex, with
a significant proportion being trace or minor
constituents31. To comprehensively identify the
chemical components in LJ, we employed UHPLC-Q-Exactive Orbitrap HRMS
for the analysis of this herbal extract. The structures of the
components were determined by comparing their LC-MS characteristics,i.e. retention time, exact molecular weight, and tandem mass
spectrometry fragmentation pattern, with reference standards, compounds
reported in the literature, as well as those registered in PubChem or
other databases. Under the optimized chromatography and mass
spectrometry conditions, a total of 50 components in all were
identified, including organic acids, flavonoids, catechins and
terpenoids (Fig. S3, S5-S54 and Table S1 ). Notably,
some flavonoids (e.g., quercetin and luteolin) and catechins (e.g.,
gallic acid and caffeic acid) in LJ contain one or more catechol groups
in their structures, which are susceptible to oxidation and formo -quinone. These o -quinones have the potential to form
covalent bonds with the cysteines of
Mpro17,32,33.