Antiviral activity of chitosan nanoparticles encapsulating silymarin (Sil–CNPs) against SARS-CoV-2 (in silico and in vitro study)

To develop a specific treatment against COVID-19, we investigated silymarin–chitosan nanoparticles (Sil–CNPs) as an antiviral agent against SARS-CoV-2 using in silico and in vitro approaches. Docking of Sil and CNPs was carried out against SARS-CoV-2 spike protein using AutoDock Vina. CNPs and Sil–CNPs were prepared by the ionic gelation method and characterized by TEM, FT-IR, zeta analysis, and the membrane diffusion method to determine the drug release profile. Cytotoxicity was tested on both Vero and Vero E6 cell lines using the MTT assay. Minimum binding energies with spike protein and ACE2 were −6.6, and −8.0 kcal mol(−1) for CNPs, and −8.9, and −9.7 kcal mol(−1) for Sil, respectively, compared to −6.6 and −8.4 kcal mol(−1) respectively for remdesivir (RMV). CNPs and Sil–CNPs were prepared at sizes of 29 nm and 82 nm. The CC50 was 135, 35, and 110 μg mL(−1) for CNPs, Sil, and Sil–CNPs, respectively, on Vero E6. The IC50 was determined at concentrations of 0.9, 12 and 0.8 μg mL(−1) in virucidal/replication assays for CNPs, Sil, and Sil–CNPs respectively using crystal violet. These results indicate antiviral activity of Sil–CNPs against SARS-CoV-2.