Abstract
BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly transmissible and has caused a pandemic named coronavirus disease 2019 (COVID-19), which has quickly spread worldwide. Although several therapeutic agents have been evaluated or approved for the treatment of COVID-19 patients, efficacious antiviral agents are still lacking. An attractive therapeutic target for SARS-CoV-2 is the main protease (Mpro), as this highly conserved enzyme plays a key role in viral polyprotein processing and genomic RNA replication. Therefore, the identification of efficacious antiviral agents against SARS-CoV-2 Mpro using a rapid, miniaturized and economical high-throughput screening (HTS) assay is of the highest importance at the present.ResultsIn this study, we first combined the fluorescence polarization (FP) technique with biotin-avidin system (BAS) to develop a novel and step-by-step sandwich-like FP screening assay to quickly identify SARS-CoV-2 Mpro inhibitors from a natural product library. Using this screening assay, dieckol, a natural phlorotannin component extracted from a Chinese traditional medicine Ecklonia cava, was identified as a novel competitive inhibitor against SARS-CoV-2 Mpro in vitro with an IC50 value of 4.5 ± 0.4 µM. Additionally, dieckol exhibited a high affinity with SARS-CoV-2 Mpro using surface plasmon resonance (SPR) analysis and could bind to the catalytic sites of Mpro through hydrogen-bond interactions in the predicted docking model.ConclusionsThis innovative sandwich-like FP screening assay enables the rapid discovery of antiviral agents targeting viral proteases, and dieckol will be an excellent lead compound for generating more potent and selective antiviral agents targeting SARS-CoV-2 Mpro.
Highlights
In December 2019, novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), quickly became a global ongoing pandemic
Remdesivir was recently approved by the Food and Drug Administration (FDA) for the treatment of hospitalized patients with COVID-19, but the trail from World Health Organization (WHO) showed that remdesivir has little benefit or no impact on survival for COVID-19 patients [1, 2]
Preparation of the highly active SARS‐CoV‐2 main protease A codon-optimized SARS-CoV-2 Mpro gene was cloned into a pET-21a(+) vector, and the soluble Mpro was expressed in E. coli Rosetta (DE3) cells
Summary
In December 2019, novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), quickly became a global ongoing pandemic. Viral genomic RNA adequately utilizes the host ribosome to translate two polyproteins (pp1a and pp1ab), which are efficiently cleaved by the main protease (Mpro) and papain-like protease (PLpro) to release 16 non-structural proteins (nsps) for viral genomic RNA replication. During this proteolytic processing, Mpro is responsible for specific cleavage sites to generate nsps [6]. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly transmissible and has caused a pandemic named coronavirus disease 2019 (COVID-19), which has quickly spread worldwide. The identification of efficacious antiviral agents against SARS-CoV-2 Mpro using a rapid, miniaturized and economical high-throughput screening (HTS) assay is of the highest importance at the present
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