Ginkgolic acid and anacardic acid are specific covalent inhibitors of SARS-CoV-2 cysteine proteases

Abstract

Background In the urgent campaign to develop therapeutics against SARS-CoV-2, natural products have been an important source of new lead compounds. Results We herein identified two natural products, ginkgolic acid and anacardic acid, as inhibitors using a high-throughput screen targeting the SARS-CoV-2 papain-like protease (PLpro). Moreover, our study demonstrated that the two hit compounds are dual inhibitors targeting the SARS-CoV-2 3-chymotrypsin-like protease (3CLpro) in addition to PLpro. A mechanism of action study using enzyme kinetics further characterized the two compounds as irreversible inhibitors against both 3CLpro and PLpro. Significantly, both identified compounds inhibit SARS-CoV-2 replication in vitro at nontoxic concentrations. Conclusions Our finding provides two novel natural products as promising SARS-CoV-2 antivirals.

Identification of a dual acting SARS-CoV-2 proteases inhibitor through in silico design and step-by-step biological characterization

“…Cellular screenings have not been performed for these molecules and there is a general lack of knowledge concerning their efficacy and safety in a relevant biological environment, though ebselen is largely considered non-cytotoxic. On the other hand, drug repurposing in silico protocols have highlighted some natural and synthetic products as dual M pro and PL pro inhibitors [ 52 , 53 ]. Ginkgolic and anacardic acids, in particular, showed moderate potencies in enzymatic assays, especially over PL pro , cellular plaque formation IC 50 s in the high micromolar range, but also comparable CC 50 values [ 52 ].…”

“…On the other hand, drug repurposing in silico protocols have highlighted some natural and synthetic products as dual M pro and PL pro inhibitors [ 52 , 53 ]. Ginkgolic and anacardic acids, in particular, showed moderate potencies in enzymatic assays, especially over PL pro , cellular plaque formation IC 50 s in the high micromolar range, but also comparable CC 50 values [ 52 ]. Ma and coworkers also showed that several compounds identified through in silico screening as potential multitarget proteases inhibitors completely lack of cellular antiviral activity, despite the high potencies showed in enzymatic assays.…”

3CLpro and PLpro affinity, a docking study to fight COVID19 based on 900 compounds from PubChem and literature. Are there new drugs to be found?

“…In addition, we provide a set of previously published redocked compounds with reported half maximal inhibitory concentration (IC 50 ) values against 3CL pro [ 38 , 73 , 87 , 88 ] and PL pro [ 40 , [89] , [90] , [91] , [92] ] to give the interested reader more detailed view on the docking score vs. dose concentration relation of in vitro tested compounds. Refer to the supplementary materials in respective .xlsx documents, sheets IC 50 _dockings.…”

Natural Bioactive Molecules as Potential Agents Against SARS-CoV-2

“…The most potent inhibitor was papyriflavonol A (82), which presented anti-SARS-CoV PL pro activity with an IC 50 of 3.70 μM (Park et al, 2017). In addition to these excellent studies of this team, Chen et al recently reported ginkgolic acid (90) and anacardic acid (91) as potent covalent inhibitors of both PL pro and 3CL pro of SARS-CoV-2, and the two compounds showed inhibitory activities against SARS-CoV-2 replication in vitro at non-toxic concentrations (Chen et al, 2021). Some other studies only reported on natural bioactive molecules that inhibited PL pro (Figure 3C).…”