2.2 Screening of the anti-SARS-CoV-2 Mpro effects of herbal products
This study screened 60 herbs with potential antiviral effects for their inhibitory effects against SARS-CoV-2 Mpro. The proteolytic activity of Mpro was evaluated through a fluorescence resonance energy transfer (FRET) assay utilizing a fluorescently tagged substrate (Dabcyl-KNSTLQSGLRK-Edans). The procedures were conducted in a 96-well black plate, following the steps outlined in the reported study24,25. The inhibitory activities of LJ extract and individual constituents in LJ anti-SARS-CoV-2 Mpro were evaluated using identical methods mentioned above.
2.3 Global chemical analysis of LJ by UHPLC-Q-Exactive Orbitrap HRMS
The comprehensive analysis of the components in LJ was performed using an ultra-high performance liquid chromatography system (Dionex UltiMate 3000, Thermo Fisher Scientific) coupled to a Q-Exactive Orbitrap high resolution mass spectrometer (Q-Exactive HRMS, Thermo Fisher Scientific)26. The liquid chromatography and mass spectrometry conditions are detailed in the supplementary material. To differentiate isomers and reduce false positive results, component identification was based on their accurate molecular weights and comparison of retention times and tandem mass spectrometry fragmentation patterns with reference standards.