HSBDF-Derived Bioactive Components Broadly Inhibit Enteroviruses by Targeting 3C Protease and Attenuating Inflammatory Responses.

Human enteroviruses are important pathogens of hand-foot-and-mouth disease, poliomyelitis, and encephalitis, etc., posing substantial global health burdens with no specific approved therapeutics. While traditional Chinese medicine (TCM) has demonstrated antiviral potential during the COVID-19 pandemic, its efficacy and pharmacodynamic material basis against enteroviruses remains underexplored. Here, we systematically characterized the broad-spectrum anti-enterovirus activity of Huashi Baidu Formula (HSBDF), a clinically approved TCM for COVID-19, and identified three flavonoid compounds as its active components responsible for this antiviral effect. Transcriptomics analysis revealed that HSBDF attenuated CV-A9-induced inflammation by modulating MAPK and NF-κB signaling pathways. High Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS) analysis identified 152 chemical compounds in HSBDF, among which three flavonoids-velutin, isorhamnetin, and (-)-epicatechin gallate-exhibited potent pan-enteroviral inhibition. Mechanistically, these compounds suppressed the activity of 3C proteases in enteroviruses, while concurrently attenuating CV-A9-induced upregulation of IL-6, TNF-α, MCP-1, and COX-2. Utilizing a BALB/c young mouse model, it was demonstrated that the HSBDF and its compound velutin effectively suppressed viral replication in vivo. Collectively, this study advances TCM-based strategies for enterovirus therapy exemplified by HSBDF and highlights flavonoid scaffolds as promising candidates for developing broad-spectrum anti-enteroviral agents.