Related Experiment Video
Updated: Jun 8, 2026

A Fluorescence-based Protocol for Preliminary Screening of Protein Synthesis Inhibitors from Natural Sources
Published on: January 27, 2026
Biflavonoids from Torreya nucifera displaying SARS-CoV 3CL(pro) inhibition
Young Bae Ryu1, Hyung Jae Jeong, Jang Hoon Kim
1Eco-Friendly Biomaterial Research Center and AI Control Material Research Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup 580-185, Republic of Korea.
Abstract:
As part of our search for botanical sources of SARS-CoV 3CL(pro) inhibitors, we selected Torreya nucifera, which is traditionally used as a medicinal plant in Asia. The ethanol extract of T. nucifera leaves exhibited good SARS-CoV 3CL(pro) inhibitory activity (62% at 100μg/mL). Following bioactivity-guided fractionation, eight diterpenoids (1-8) and four biflavonoids (9-12) were isolated and evaluated for SARS-CoV 3CL(pro) inhibition using fluorescence resonance energy transfer analysis. Of these compounds, the biflavone amentoflavone (9) (IC(50)=8.3μM) showed most potent 3CL(pro) inhibitory effect. Three additional authentic flavones (apigenin, luteolin and quercetin) were tested to establish the basic structure-activity relationship of biflavones. Apigenin, luteolin, and quercetin inhibited 3CL(pro) activity with IC(50) values of 280.8, 20.2, and 23.8μM, respectively. Values of binding energy obtained in a molecular docking study supported the results of enzymatic assays. More potent activity appeared to be associated with the presence of an apigenin moiety at position C-3' of flavones, as biflavone had an effect on 3CL(pro) inhibitory activity.
Related Concept Videos
Inhibitors Of Virion Release
Inhibitors of Virion Maturation and Assembly
Inhibitors of Viral Protein Synthesis
Inhibition of CDK Activity
Inhibition of Cdk Activity
Antiviral Nucleoside Inhibitors

