Systematically uncovering the absorbed effective substances of Radix Scutellaria-licorice drug pair in rat plasma against COVID-19 using a combined UHPLC-Q-TOF-MS analysis and target network pharmacology.

Radix Scutellaria-Licorice drug pair (RSLDP), a frequently used herbal pair with the effect of clearing heat and detoxifying, is the commonly employed drug pair in TCM prescriptions for the treatment of COVID-19. Until now, the metabolism feature and anti-COVID-19 mechanism of RSLDP have not been fully elucidated. In this study, a sensitive and rapid method was developed for the separation and identification of the absorbed constituents of RSLDP in the rat plasma by UHPLC-QTOF-MS. Additionally, we optimized the conventional methodologies of network pharmacology and proposed a new concept called target network pharmacology (T-NP). It used the absorbed constituents and the corresponding targets to generate a compound-target network, and compared to conventional network pharmacology, it could reduce false-positive results. A total of 85 absorbed constituents were identified or tentatively characterized in dosed plasma, including 32 components in the group of Radix Scutellaria, 27 components in the group of Licorice, and 65 components in the group of RSLDP. The results showed that the compatibility of Radix Scutellaria and Licorice increased the number of components in vivo. We found that 106 potential targets among the 61 active compounds in RSLDP were related to COVID-19. And 12 targets (STAT3, AKT1, EGFR, HSP9AA1, MAPK3, JUN, IL6, VEGFA, TNF, IL2, RELA, and STAT1) could be core targets for RSLDP in treating COVID-19. Results from these targets indicate that RSLDP treatment of COVID-19 mainly involves response to chemical stress, response to oxygenates, positive regulation of cytokines, PI3K-Akt signaling pathway, AGE-RAGE signaling pathway for diabetic complications, virus-related pathways such as novel coronavirus and human cytomegalovirus infection, inflammatory immune-related pathways, and so on. The metabolism feature of RSLDP in vivo was systematically uncovered. The combined use of the T-NP method could discover potential drug targets and disclose the biological processes of RSLDP, which will clarify the potential mechanisms of RSLDP in the treatment of COVID-19.