Phycobilins as potent food bioactive broad-spectrum inhibitor compounds against M ^pro and PL ^pro of SARS-CoV-2 and other coronaviruses: A preliminary Study

In the twenty first century, we have witnessed three corona virus outbreaks; SARS in 2003, MERS in 2012 and ongoing pandemic COVID-19. To prevent outbreaks by novel mutant strains, we need broad-spectrum antiviral agents that are effective against wide array of coronaviruses. In this study, we scientifically investigated potent food bioactive broad-spectrum antiviral compounds by targeting M ^pro and PL ^pro proteases of CoVs using in silico and in vitro approaches. The results revealed that phycocyanobilin (PCB) showed potential inhibitor activity against both proteases. PCB had best binding affinity to M ^pro and PL ^pro with IC ₅₀ values of 71 μm and 62 μm, respectively. In addition, in silico studies of M ^pro and PL ^pro enzymes of other human and animal CoVs indicated broad spectrum inhibitor activity of the PCB. Like PCB, other phycobilins such as phycourobilin (PUB), Phycoerythrobilin (PEB) and Phycoviolobilin (PVB) showed similar binding affinity to SARS-CoV-2 M ^pro and PL ^pro