Molecular docking and molecular dynamics simulation studies reveal repurposing I-Motif ligand as a promising protease inhibitor against SARS-CoV-2 variants

The COVID-19 caused by the SARS-CoV-2 virus has escalated into a global pandemic, urgently necessitating effective treatments. Tremendous research of the SARS-CoV-2 main protease have enabled insight understanding of its mechanism and potential inhibitors. Due to its crucial role in viral replication, the protease is considered an attractive target for antiviral therapy. This study aimed to identify novel potent inhibitors of main protease protein by repurposing i-Motif (iM) binding compounds from the G4LDB database. iM ligands are known for their ability to stabilise iM structures in DNA, and their repurposing as protein inhibitors is an alternative therapeutic approach. To achieve this, we performed <i>in silico</i> studies with six iM binding compounds. Molecular docking, molecular dynamics (MD) simulations and MM/GBSA binding free energy analysis revealed favourable conformational stability and superior binding affinity of the three proposed iM ligands, including iML0042 (−59.91 ± 3.82 kcal/mol), iML0043 (−56.37 ± 3.87 kcal/mol), and iML0094 (−84.68 ± 3.40 kcal/mol), to SARS-CoV-2 Mpro variants compared to the reference inhibitor nirmatrelvir (−34.35 ± 3.74 kcal/mol). The results suggested that repurposing iM ligands as protease inhibitors is a promising strategy. Our findings revealed significant candidate inhibitors and are recommended for further development as potential protease inhibitors against SARS-CoV-2.