Comprehensive characterization of metabolites and metabolic profiles in plasma has considerable sig-nificance in determining the efficacy and safety of traditional Chinese medicine(TCM)in vivo.However,this process is usually hindered by the insufficient characteristic fragments of metabolites,ubiquitous matrix interference,and complicated screening and identification procedures for metabolites.In this study,an effective strategy was established to systematically characterize the metabolites,deduce the metabolic pathways,and describe the metabolic profiles of bufadienolides isolated from Venenum Bufonis in vivo.The strategy was divided into five steps.First,the blank and test plasma samples were injected into an ultra-high performance liquid chromatography/linear trap quadrupole-orbitrap-mass spectrometry(MS)system in the full scan mode continuously five times to screen for valid matrix compounds and metabolites.Second,an extension-mass defect filter model was established to obtain the targeted precursor ions of the list of bufadienolide metabolites,which reduced approximately 39％of the interfering ions.Third,an acquisition model was developed and used to trigger more tandem MS(MS/MS)fragments of precursor ions based on the targeted ion list.The acquisition mode enhanced the acquisition capability by approximately four times than that of the regular data-dependent acquisition mode.Fourth,the acquired data were imported into Compound Discoverer software for identification of metabolites with metabolic network prediction.The main in vivo metabolic pathways of bufadienolides were elucidated.A total of 147 metabolites were characterized,and the main biotransformation reactions of bufadienolides were hydroxylation,dihydroxylation,and isomerization.Finally,the main prototype bufadienolides in plasma at different time points were determined using LC-MS/MS,and the metabolic profiles were clearly identified.This strategy could be widely used to elucidate the metabolic profiles of TCM preparations or Chinese patent medicines in vivo and provide critical data for rational drug use.

Huashi Baidu prescription (HSBDF), recommended in the Guideline for the Diagnosis and Treatment of Novel Coronavirus (2019-nCoV) Pneumonia (On Trials, the Seventh Edition), was clinically used to treat severe corona virus disease 2019 (COVID-19) with cough, blood-stained sputum, inhibited defecation, red tongue etc. symptoms. This study was aimed to elucidate and profile the knowledge on its chemical constituents and the potential anti-inflammatory effect in vitro. In the study, the chemical constituents in extract of HSBDF were characterized by UPLC-Q-TOF/MS in both negative and positive modes, and the pro-inflammatory cytokines were measured by enzyme-linked immunosorbent assays (ELISA) to determine the effects of HSBDF in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The results showed that a total of 217 chemical constituents were tentativedly characterized in HSBDF. Moreover, HSBDF could alleviate the expression levels of IL-6 and TNF-α in the cell models, indicating that the antiviral effects of HSBDF might be associated with regulation of the inflammatory cytokines production in RAW264.7 cells. We hope that the results could be served as the basic data for further study of HSBDF on anti-COVID-19 effect.
Anti-Inflammatory Agents/therapeutic use* ; Antiviral Agents/therapeutic use* ; COVID-19/drug therapy* ; Drugs, Chinese Herbal/therapeutic use* ; Humans ; Plant Extracts/therapeutic use* ; SARS-CoV-2/drug effects*