In silico studies of selected xanthophylls as potential candidates against SARS-CoV-2 targeting main protease (Mpro) and papain-like protease (PLpro)

Introduction: The main protease (Mpro) and the papain-like protease (PLpro) are essential for the replication of SARS-CoV-2. Both proteases can be targets for drugs acting against SARS-CoV-2. Objective: This paper aims to investigate the in silico activity of nine xanthophylls as inhibitors of Mpro and PLpro. Methods: The structures of Mpro (PDB-ID: 6LU7) and PLpro (PDB-ID: 6W9C) were obtained from RCSB Protein Data Bank and developed with BIOVIA Discovery Studio. Active sites of proteins were performed using CASTp. For docking the PyRx was used. Pharmacokinetic parameters of ADMET were evaluated using SwissADME and pkCSM. Results: β-cryptoxanthin exhibited the highest binding energy:-7.4 kcal/mol in the active site of Mpro. In PLpro active site, the highest binding energy had canthaxanthin of-9.4 kcal/mol, astaxanthin-9.3 kcal/mol, flavoxanthin-9.2 kcal/mol and violaxanthin-9.2 kcal/mol. ADMET studies presented lower toxicity of xanthophylls in comparison to ritonavir and ivermectin. Conclusion: Our findings suggest that xanthophylls can be used as potential inhibitors against SARS-CoV-2 main protease and papain-like protease. © 2021 Tomasz M. Karpinski et al., published by Sciendo.