Chemical Compositions of Lianqiao (Forsythia suspensa) Extracts and Their Potential Health Benefits

This study evaluated the fruits of Forsythia suspensa (Lianqiao), an important economic crop, for the chemical components of its water and ethanol extracts, inhibitory effects on SARS-CoV-2 virus spike protein binding to ACE2, inhibition of ACE2 activity, and capacity to scavenge free radicals. A total of 42 compounds were tentatively identified in the extracts via HPLC-MS/MS analysis. The water extract showed a greater ACE2 inhibition but a weaker inhibition on SARS-CoV-2 spike protein binding to ACE2 than the ethanol extract on a per-botanical-weight-concentration basis. The phenolic content was found to be greater in the water extract at 45.19 mg GAE/g dry botanical weight than in the ethanol extract (6.89 mg GAE/g dry botanical). Furthermore, the water extract had greater scavenging capacities against HO^●, DPPH^●, and ABTS^●+ at 448.48, 66.36, and 121.29 µmol TE/g dry botanical, respectively, as compared to that of the ethanol extract (154.04, 3.55, and 33.83 µmol TE/g dry botanical, respectively). These results warrant further research into, and the development of, the potential COVID-19-preventive applications of Lianqiao and its extracts.