tetano
Editor, Senior Moderator
Med Chem Res
. 2022 May 12;1-7.
doi: 10.1007/s00044-022-02903-0. Online ahead of print.
Invalidation of dieckol and 1,2,3,4,6-pentagalloylglucose (PGG) as SARS-CoV-2 main protease inhibitors and the discovery of PGG as a papain-like protease inhibitor
Haozhou Tan[SUP] 1 [/SUP], Chunlong Ma[SUP] 2 [/SUP], Jun Wang[SUP] 1 [/SUP]
Affiliations
Abstract
The COVID-19 pandemic spurred a broad interest in antiviral drug discovery. The SARS-CoV-2 main protease (M[SUP]pro[/SUP]) and papain-like protease (PL[SUP]pro[/SUP]) are attractive antiviral drug targets given their vital roles in viral replication and modulation of host immune response. Structurally disparate compounds were reported as M[SUP]pro[/SUP] and PL[SUP]pro[/SUP] inhibitors from either drug repurposing or rational design. Two polyphenols dieckol and 1,2,3,4,6-pentagalloylglucose (PGG) were recently reported as SARS-CoV-2 M[SUP]pro[/SUP] inhibitors. With our continuous interest in studying the mechanism of inhibition and resistance of M[SUP]pro[/SUP] inhibitors, we report herein our independent validation/invalidation of these two natural products. Our FRET-based enzymatic assay showed that neither dieckol nor PGG inhibited SARS-CoV-2 M[SUP]pro[/SUP] (IC[SUB]50[/SUB] > 20 µM), which is in contrary to previous reports. Serendipitously, PGG was found to inhibit the SARS-CoV-2 PL[SUP]pro[/SUP] with an IC[SUB]50[/SUB] of 3.90 µM. The binding of PGG to PL[SUP]pro[/SUP] was further confirmed in the thermal shift assay. However, PGG was cytotoxic in 293T-ACE2 cells (CC[SUB]50[/SUB] = 7.7 µM), so its intracellular PL[SUP]pro[/SUP] inhibitory activity could not be quantified by the cell-based Flip-GFP PL[SUP]pro[/SUP] assay. In addition, we also invalidated ebselen, disulfiram, carmofur, PX12, and tideglusib as SARS-CoV-2 PL[SUP]pro[/SUP] inhibitors using the Flip-GFP assay. Overall, our results call for stringent hit validation, and the serendipitous discovery of PGG as a putative PL[SUP]pro[/SUP] inhibitor might worth further pursuing. Graphical abstract.
Keywords: Antiviral; Coronavirus; Main protease; Papain-like protease; SARS-CoV-2.
. 2022 May 12;1-7.
doi: 10.1007/s00044-022-02903-0. Online ahead of print.
Invalidation of dieckol and 1,2,3,4,6-pentagalloylglucose (PGG) as SARS-CoV-2 main protease inhibitors and the discovery of PGG as a papain-like protease inhibitor
Haozhou Tan[SUP] 1 [/SUP], Chunlong Ma[SUP] 2 [/SUP], Jun Wang[SUP] 1 [/SUP]
Affiliations
- PMID: 35578732
- PMCID: PMC9095416
- DOI: 10.1007/s00044-022-02903-0
Abstract
The COVID-19 pandemic spurred a broad interest in antiviral drug discovery. The SARS-CoV-2 main protease (M[SUP]pro[/SUP]) and papain-like protease (PL[SUP]pro[/SUP]) are attractive antiviral drug targets given their vital roles in viral replication and modulation of host immune response. Structurally disparate compounds were reported as M[SUP]pro[/SUP] and PL[SUP]pro[/SUP] inhibitors from either drug repurposing or rational design. Two polyphenols dieckol and 1,2,3,4,6-pentagalloylglucose (PGG) were recently reported as SARS-CoV-2 M[SUP]pro[/SUP] inhibitors. With our continuous interest in studying the mechanism of inhibition and resistance of M[SUP]pro[/SUP] inhibitors, we report herein our independent validation/invalidation of these two natural products. Our FRET-based enzymatic assay showed that neither dieckol nor PGG inhibited SARS-CoV-2 M[SUP]pro[/SUP] (IC[SUB]50[/SUB] > 20 µM), which is in contrary to previous reports. Serendipitously, PGG was found to inhibit the SARS-CoV-2 PL[SUP]pro[/SUP] with an IC[SUB]50[/SUB] of 3.90 µM. The binding of PGG to PL[SUP]pro[/SUP] was further confirmed in the thermal shift assay. However, PGG was cytotoxic in 293T-ACE2 cells (CC[SUB]50[/SUB] = 7.7 µM), so its intracellular PL[SUP]pro[/SUP] inhibitory activity could not be quantified by the cell-based Flip-GFP PL[SUP]pro[/SUP] assay. In addition, we also invalidated ebselen, disulfiram, carmofur, PX12, and tideglusib as SARS-CoV-2 PL[SUP]pro[/SUP] inhibitors using the Flip-GFP assay. Overall, our results call for stringent hit validation, and the serendipitous discovery of PGG as a putative PL[SUP]pro[/SUP] inhibitor might worth further pursuing. Graphical abstract.
Keywords: Antiviral; Coronavirus; Main protease; Papain-like protease; SARS-CoV-2.