LC/MS-guided isolation and GNPS procedures to identify flavonoid of HCoV-OC43 inhibitors

The screening of based target compounds supported by LC/MS, MS/MS and Global Natural Products Social (GNPS) used to identify the compounds 1-10 of Butea monsperma. They were evaluated in human malignant embryonic rhabdomyoma cells (RD cells) infected with Human coronavirus OC43 (HCoV-OC43) and showed significant inhibitory activity. Target inhibition tests showed that compounds 6 and 8 inhibited the proteolytic enzyme 3CLpro, which is widely present in coronavirus and plays an important role in the replication process, with an effective IC₅₀ value. The study confirmed that dioxymethylene of compound 8 may be a key active fragment in inhibiting coronavirus (EC₅₀ 7.2 μM, SI > 139.1). The results have led to identifying natural bioactive compounds for possible inhibiting HCoV-OC43 and developing drug for Traditional Chinese Medicine (TCM).