Ginkgolic acid as a fusion inhibitor: targeting RBD-ACE2 interaction with in silico, in vitro evidence of allosteric modulation and potent virucidal effect.

BACKGROUND: This study investigates Ginkgolic acid, a naturally occurring phenolic compound from Ginkgo biloba, for its potential to inhibit SARS-CoV-2 by targeting the RBD-ACE2 interface through a combination of computational and in vitro methodologies.

METHODS: In silico molecular docking and 500 ns molecular dynamics (MD) simulations were employed to examine the binding conformation and stability of Ginkgolic acid at the RBD-ACE2 interface. In vitro studies included cytotoxicity profiling, plaque reduction assays, qRT-PCR, luciferase-based viral entry quantification, and membrane fusion inhibition in Vero E6 and ACE2-expressing HEK293T cells.

RESULTS: Ginkgolic acid demonstrated dose-dependent antiviral activity in Vero E6 cells with half-maximal inhibitory concentration (IC50) values ranging from 0.025 to 0.102 µM. MD simulations revealed its strong binding affinity at the RBD-ACE2 interface, particularly through interactions with conserved residues His34 and Asp38, leading to increased inter-residue distances and destabilization of the complex. In vitro assays confirmed significant virucidal activity, reduced viral entry, and inhibition of spike-mediated membrane fusion. Despite limited intracellular uptake, its antiviral efficacy appears to be predominantly extracellular.

CONCLUSION: Ginkgolic acid acts as an allosteric modulator and fusion inhibitor by targeting conserved RBD-ACE2 interface residues, disrupting viral attachment and fusion. Its dual mechanism-direct virucidal effect and host-cell entry inhibition-presents a promising scaffold for future antiviral development. These findings warrant further preclinical validation to assess its efficacy across SARS-CoV-2 variants.