Profiling, screening, and determination of the antioxidant and anti-inflammatory constituents in Xuanfei Baidu granules by UHPLC-QTOF-MS and UHPLC-DAD

Xuanfei Baidu granules (XBG) are one of the well-known prescriptions developed against COVID-19. However, the effective quality markers (Q-markers) of XBG remain unclear, and there is an urgent need for global quality control of XBG to ensure its safety and efficacy in clinics. This study aims to contribute to the selection of Q-markers dedicated to the safety and clinical application of XBG. To begin with, the small molecular constituents of XBG were characterized and identified by an integrative ultrahigh performance liquid chromatography (UHPLC)-quadrupole time-of-flight (QTOF)-mass spectrometry (MS) analysis of MS/MS molecular networking (MN), comparison with reference standards, and in-house library search. And 143 constituents were identified from XBG, including 64 flavonoids, 24 triterpenoids, 33 phenylpropanoids, six alkaloids, three iridoids, one sesquiterpenoid, and 12 other phenolic acids. At the same time, the polysaccharide component of XBG was profiled by high-performance gel-permeation chromatography (HPGPC)-evaporative light scattering detector (ELSD), PMP-HPLC-DAD, nuclear magnetic resonance (1D NMR), and Fourier transform infrared (FT-IR) experiments, and it was found that XBG contained two or more homogeneous polysaccharides, which were mainly composed of the monosaccharides, namely mannose, xylose, galacturonic acid, glucose, galactose, and arabinose. Subsequently, fractions and components from XBG were screened through DPPH· and OH radical scavenging and reducing power assays, and a DPPH·-UHPLC-DAD analysis for the constituents with antioxidant propensities, and were further screened by using a Griess method to determine their effects on the production of nitric oxide (NO) in LPS-injured RAW264.7 macrophages, and a COX2-UHPLC-DAD analysis for those with anti-inflammatory potentials. Finally, hastatoside, verbenalin, polydatin, acteoside, isoacteoside, naringin, and glycyrrhizic acid were ultimately selected as the effective Q-markers for XBG, and their contents (%) were determined as 3.350 ± 0.0502%, 2.641 ± 0.04992%, 2.459 ± 0.07142%, 1.299 ± 0.06612%, 0.958 ± 0.03432%, 26.598 ± 0.609%, and 1.819 ± 0.0542%, respectively. Our study reveals the profiles of both small molecular and polysaccharide components in XBG, and a content determination method for the selected small molecular Q-markers with antioxidant and anti-inflammatory potentials.