ABSTRACT
Forsythia suspensa (Lianqiao) has long been touted for its anti-viral effects in folklore. Although promising, limited research were conducted to evaluate its potential in defending the severe acute respiratory syndrome coronavirus (SARS-CoV-2). This study evaluated the fruits of Forsythia suspensa (Lianqiao), an important economic crop, for the chemical components of its water and ethanol extracts, along with their inhibitory effects on SARS-CoV-2 spike protein binding to angiotensin-converting enzyme 2 (ACE2), inhibitions of ACE2 activity, and capacities to scavenge the selected free radicals. A total of 42 compounds were tentatively identified in the extracts by HPLC-MS/MS analysis. Both water and ethanol extracts of Lianqiao showed great inhibition of ACE2 activity and the binding affinity between SARS CoV-2 spike protein and ACE2. Furthermore, the water extract had greater scavenging capacities against HO●, DPPH● and ABTS●+ than the ethanol extract. Findings of this research contribute to the knowledge of different extraction solvent systems and support the potential of Lianqiao in reducing the risk of coronavirus infection and alleviating the symptoms after infection.