In silico studies of phycobilins as potential candidates for inhibitors of viral proteins associated with COVID-19

In this in silico study, it was investigated whether phycobilins (phycocyanobilin, phycoerythrobilin and phycourobilin) could be inhibitors of the activity of the main proteins of the SARS-CoV-2 virus. All chromophores exhibited a binding energy value of ≥–37 kJ mol-1 for PLpro-WT, PLpro- -C111S, helicase-ANP binding site, Nsp3-macrodomain, Nsp3-MES site and Nsp10/14-N7-Mtase. Phycocyanobilin showed the highest binding energy of –44.77 kJ mol-1 against the target protein PLpro-C111S. It was found that, apart from the hydrogen bonds and hydrophobic interactions, phycobilins also form electrostatic interactions with the SARS-CoV-2 proteins. The network of non-covalent interactions was found to be important for the stability of the examined virus proteins. All phycobilins have good pharmacokinetic and drug- -likeness properties. This study’s results suggest that the screened phycobilins could serve as promising drugs for the treatment of COVID-19 with further rigorous validation studies.