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1.
SLAS Discov ; 27(1): 8-19, 2022 01.
Article in English | MEDLINE | ID: covidwho-1641663

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 responsible for COVID-19 remains a persistent threat to mankind, especially for the immunocompromised and elderly for which the vaccine may have limited effectiveness. Entry of SARS-CoV-2 requires a high affinity interaction of the viral spike protein with the cellular receptor angiotensin-converting enzyme 2. Novel mutations on the spike protein correlate with the high transmissibility of new variants of SARS-CoV-2, highlighting the need for small molecule inhibitors of virus entry into target cells. We report the identification of such inhibitors through a robust high-throughput screen testing 15,000 small molecules from unique libraries. Several leads were validated in a suite of mechanistic assays, including whole cell SARS-CoV-2 infectivity assays. The main lead compound, calpeptin, was further characterized using SARS-CoV-1 and the novel SARS-CoV-2 variant entry assays, SARS-CoV-2 protease assays and molecular docking. This study reveals calpeptin as a potent and specific inhibitor of SARS-CoV-2 and some variants.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Cysteine Proteinase Inhibitors/pharmacology , Dipeptides/pharmacology , Virus Attachment/drug effects , Virus Internalization/drug effects , Angiotensin-Converting Enzyme 2/metabolism , Animals , Cathepsin L/antagonists & inhibitors , Cell Line , Chlorocebus aethiops , Drug Evaluation, Preclinical , Drug Repositioning , HEK293 Cells , Humans , Molecular Docking Simulation , SARS-CoV-2/drug effects , SARS-CoV-2/growth & development , Serine Endopeptidases/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
2.
J Am Chem Soc ; 143(49): 20697-20709, 2021 12 15.
Article in English | MEDLINE | ID: covidwho-1550253

ABSTRACT

The main protease (Mpro) is a validated antiviral drug target of SARS-CoV-2. A number of Mpro inhibitors have now advanced to animal model study and human clinical trials. However, one issue yet to be addressed is the target selectivity over host proteases such as cathepsin L. In this study we describe the rational design of covalent SARS-CoV-2 Mpro inhibitors with novel cysteine reactive warheads including dichloroacetamide, dibromoacetamide, tribromoacetamide, 2-bromo-2,2-dichloroacetamide, and 2-chloro-2,2-dibromoacetamide. The promising lead candidates Jun9-62-2R (dichloroacetamide) and Jun9-88-6R (tribromoacetamide) had not only potent enzymatic inhibition and antiviral activity but also significantly improved target specificity over caplain and cathepsins. Compared to GC-376, these new compounds did not inhibit the host cysteine proteases including calpain I, cathepsin B, cathepsin K, cathepsin L, and caspase-3. To the best of our knowledge, they are among the most selective covalent Mpro inhibitors reported thus far. The cocrystal structures of SARS-CoV-2 Mpro with Jun9-62-2R and Jun9-57-3R reaffirmed our design hypothesis, showing that both compounds form a covalent adduct with the catalytic C145. Overall, these novel compounds represent valuable chemical probes for target validation and drug candidates for further development as SARS-CoV-2 antivirals.


Subject(s)
Acetamides/pharmacology , Antiviral Agents/pharmacology , Coronavirus 3C Proteases/antagonists & inhibitors , Protease Inhibitors/pharmacology , SARS-CoV-2/drug effects , Animals , Antiviral Agents/chemistry , Cathepsin L/antagonists & inhibitors , Drug Design , Drug Discovery , Enzyme Inhibitors/pharmacology , Humans , Models, Molecular , Molecular Dynamics Simulation , Structure-Activity Relationship , Substrate Specificity
3.
J Med Chem ; 65(4): 2956-2970, 2022 02 24.
Article in English | MEDLINE | ID: covidwho-1500413

ABSTRACT

Cathepsin L is a key host cysteine protease utilized by coronaviruses for cell entry and is a promising drug target for novel antivirals against SARS-CoV-2. The marine natural product gallinamide A and several synthetic analogues were identified as potent inhibitors of cathepsin L with IC50 values in the picomolar range. Lead molecules possessed selectivity over other cathepsins and alternative host proteases involved in viral entry. Gallinamide A directly interacted with cathepsin L in cells and, together with two lead analogues, potently inhibited SARS-CoV-2 infection in vitro, with EC50 values in the nanomolar range. Reduced antiviral activity was observed in cells overexpressing transmembrane protease, serine 2 (TMPRSS2); however, a synergistic improvement in antiviral activity was achieved when combined with a TMPRSS2 inhibitor. These data highlight the potential of cathepsin L as a COVID-19 drug target as well as the likely need to inhibit multiple routes of viral entry to achieve efficacy.


Subject(s)
Antimicrobial Cationic Peptides/pharmacology , Antiviral Agents/pharmacology , Biological Products/pharmacology , COVID-19/drug therapy , Cathepsin L/antagonists & inhibitors , Cysteine Proteinase Inhibitors/pharmacology , SARS-CoV-2/drug effects , A549 Cells , Animals , Antimicrobial Cationic Peptides/chemical synthesis , Antimicrobial Cationic Peptides/chemistry , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Biological Products/chemical synthesis , Biological Products/chemistry , COVID-19/metabolism , Cathepsin L/metabolism , Chlorocebus aethiops , Cysteine Proteinase Inhibitors/chemical synthesis , Cysteine Proteinase Inhibitors/chemistry , Dose-Response Relationship, Drug , Humans , Microbial Sensitivity Tests , Molecular Conformation , Proteomics , Structure-Activity Relationship , Vero Cells
4.
ACS Chem Biol ; 16(4): 642-650, 2021 04 16.
Article in English | MEDLINE | ID: covidwho-1387141

ABSTRACT

Host-cell cysteine proteases play an essential role in the processing of the viral spike protein of SARS coronaviruses. K777, an irreversible, covalent inactivator of cysteine proteases that has recently completed phase 1 clinical trials, reduced SARS-CoV-2 viral infectivity in several host cells: Vero E6 (EC50< 74 nM), HeLa/ACE2 (4 nM), Caco-2 (EC90 = 4.3 µM), and A549/ACE2 (<80 nM). Infectivity of Calu-3 cells depended on the cell line assayed. If Calu-3/2B4 was used, EC50 was 7 nM, but in the ATCC Calu-3 cell line without ACE2 enrichment, EC50 was >10 µM. There was no toxicity to any of the host cell lines at 10-100 µM K777 concentration. Kinetic analysis confirmed that K777 was a potent inhibitor of human cathepsin L, whereas no inhibition of the SARS-CoV-2 cysteine proteases (papain-like and 3CL-like protease) was observed. Treatment of Vero E6 cells with a propargyl derivative of K777 as an activity-based probe identified human cathepsin B and cathepsin L as the intracellular targets of this molecule in both infected and uninfected Vero E6 cells. However, cleavage of the SARS-CoV-2 spike protein was only carried out by cathepsin L. This cleavage was blocked by K777 and occurred in the S1 domain of the SARS-CoV-2 spike protein, a different site from that previously observed for the SARS-CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of cathepsin L-mediated viral spike protein processing.


Subject(s)
Antiviral Agents/pharmacology , Cysteine Proteinase Inhibitors/pharmacology , Phenylalanine/pharmacology , Piperazines/pharmacology , SARS-CoV-2/drug effects , Tosyl Compounds/pharmacology , Animals , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Cell Line, Tumor , Chlorocebus aethiops , Humans , Microbial Sensitivity Tests , Protein Domains , Proteolysis , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells , Virus Internalization/drug effects
5.
J Med Chem ; 64(15): 11267-11287, 2021 08 12.
Article in English | MEDLINE | ID: covidwho-1319012

ABSTRACT

Cysteine proteases comprise an important class of drug targets, especially for infectious diseases such as Chagas disease (cruzain) and COVID-19 (3CL protease, cathepsin L). Peptide aldehydes have proven to be potent inhibitors for all of these proteases. However, the intrinsic, high electrophilicity of the aldehyde group is associated with safety concerns and metabolic instability, limiting the use of aldehyde inhibitors as drugs. We have developed a novel class of self-masked aldehyde inhibitors (SMAIs) for cruzain, the major cysteine protease of the causative agent of Chagas disease-Trypanosoma cruzi. These SMAIs exerted potent, reversible inhibition of cruzain (Ki* = 18-350 nM) while apparently protecting the free aldehyde in cell-based assays. We synthesized prodrugs of the SMAIs that could potentially improve their pharmacokinetic properties. We also elucidated the kinetic and chemical mechanism of SMAIs and applied this strategy to the design of anti-SARS-CoV-2 inhibitors.


Subject(s)
Aldehydes/chemistry , COVID-19/drug therapy , Chagas Disease/drug therapy , Cysteine Proteinase Inhibitors/therapeutic use , SARS-CoV-2/enzymology , Trypanosoma cruzi/enzymology , Aldehydes/metabolism , Aldehydes/pharmacology , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Cysteine Endopeptidases/metabolism , Cysteine Proteases/metabolism , Cysteine Proteinase Inhibitors/chemistry , Drug Design , Humans , Kinetics , Models, Molecular , Molecular Structure , Protozoan Proteins/antagonists & inhibitors , Protozoan Proteins/metabolism , SARS-CoV-2/drug effects , Structure-Activity Relationship , Trypanosoma cruzi/drug effects
6.
ChemMedChem ; 17(1): e202100456, 2022 01 05.
Article in English | MEDLINE | ID: covidwho-1303243

ABSTRACT

A number of inhibitors have been developed for the SARS-CoV-2 main protease (MPro ) as potential COVID-19 medications but little is known about their selectivity. Using enzymatic assays, we characterized inhibition of TMPRSS2, furin, and cathepsins B/K/L by more than a dozen of previously developed MPro inhibitors including MPI1-9, GC376, 11a, 10-1, 10-2, and 10-3. MPI1-9, GC376 and 11a all contain an aldehyde for the formation of a reversible covalent hemiacetal adduct with the MPro active site cysteine and 10-1, 10-2 and 10-3 contain a labile ester to exchange with the MPro active site cysteine for the formation of a thioester. Our data revealed that all these inhibitors are inert toward TMPRSS2 and furin. Diaryl esters also showed low inhibition of cathepsins. However, all aldehyde inhibitors displayed high potency in inhibiting three cathepsins. Their determined IC50 values vary from 4.1 to 380 nM for cathepsin B, 0.079 to 2.3 nM for cathepsin L, and 0.35 to 180 nM for cathepsin K. All aldehyde inhibitors showed similar inhibition levels toward cathepsin L. A cellular analysis indicated high potency of MPI5 and MPI8 in inhibiting lysosomal activity, which is probably attributed to their inhibition of cathepsins. Among all aldehyde inhibitors, MPI8 shows the best selectivity toward cathepsin L. With respect to cathepsins B and K, the selective indices are 192 and 150, respectively. MPI8 is the most potent compound among all aldehyde inhibitors in cellular MPro inhibition potency and anti-SARS-CoV-2 activity in Vero E6 cells. Cathepsin L has been demonstrated to play a critical role in the SARS-CoV-2 cell entry. By selectively inhibiting both SARS-CoV-2 MPro and the host cathepsin L, MPI8 potentiates dual inhibition effects to synergize its overall antiviral potency and efficacy. Due to its high selectivity toward cathepsin L that reduces potential toxicity toward host cells and high cellular and antiviral potency, we urge serious consideration of MPI8 for preclinical and clinical investigations for treating COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Cathepsin L/antagonists & inhibitors , Coronavirus 3C Proteases/antagonists & inhibitors , Protease Inhibitors/pharmacology , SARS-CoV-2/drug effects , Humans , Molecular Docking Simulation
7.
ACS Chem Biol ; 16(4): 642-650, 2021 04 16.
Article in English | MEDLINE | ID: covidwho-1160225

ABSTRACT

Host-cell cysteine proteases play an essential role in the processing of the viral spike protein of SARS coronaviruses. K777, an irreversible, covalent inactivator of cysteine proteases that has recently completed phase 1 clinical trials, reduced SARS-CoV-2 viral infectivity in several host cells: Vero E6 (EC50< 74 nM), HeLa/ACE2 (4 nM), Caco-2 (EC90 = 4.3 µM), and A549/ACE2 (<80 nM). Infectivity of Calu-3 cells depended on the cell line assayed. If Calu-3/2B4 was used, EC50 was 7 nM, but in the ATCC Calu-3 cell line without ACE2 enrichment, EC50 was >10 µM. There was no toxicity to any of the host cell lines at 10-100 µM K777 concentration. Kinetic analysis confirmed that K777 was a potent inhibitor of human cathepsin L, whereas no inhibition of the SARS-CoV-2 cysteine proteases (papain-like and 3CL-like protease) was observed. Treatment of Vero E6 cells with a propargyl derivative of K777 as an activity-based probe identified human cathepsin B and cathepsin L as the intracellular targets of this molecule in both infected and uninfected Vero E6 cells. However, cleavage of the SARS-CoV-2 spike protein was only carried out by cathepsin L. This cleavage was blocked by K777 and occurred in the S1 domain of the SARS-CoV-2 spike protein, a different site from that previously observed for the SARS-CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of cathepsin L-mediated viral spike protein processing.


Subject(s)
Antiviral Agents/pharmacology , Cysteine Proteinase Inhibitors/pharmacology , Phenylalanine/pharmacology , Piperazines/pharmacology , SARS-CoV-2/drug effects , Tosyl Compounds/pharmacology , Animals , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Cell Line, Tumor , Chlorocebus aethiops , Humans , Microbial Sensitivity Tests , Protein Domains , Proteolysis , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells , Virus Internalization/drug effects
8.
Biochem Biophys Res Commun ; 555: 134-139, 2021 05 28.
Article in English | MEDLINE | ID: covidwho-1157141

ABSTRACT

There is an urgent need for antivirals targeting the SARS-CoV-2 virus to fight the current COVID-19 pandemic. The SARS-CoV-2 main protease (3CLpro) represents a promising target for antiviral therapy. The lack of selectivity for some of the reported 3CLpro inhibitors, specifically versus cathepsin L, raises potential safety and efficacy concerns. ALG-097111 potently inhibited SARS-CoV-2 3CLpro (IC50 = 7 nM) without affecting the activity of human cathepsin L (IC50 > 10 µM). When ALG-097111 was dosed in hamsters challenged with SARS-CoV-2, a robust and significant 3.5 log10 (RNA copies/mg) reduction of the viral RNA copies and 3.7 log10 (TCID50/mg) reduction in the infectious virus titers in the lungs was observed. These results provide the first in vivo validation for the SARS-CoV-2 3CLpro as a promising therapeutic target for selective small molecule inhibitors.


Subject(s)
Amides/pharmacology , COVID-19/drug therapy , Coronavirus 3C Proteases/antagonists & inhibitors , Cysteine Proteinase Inhibitors/pharmacology , Disease Models, Animal , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Amides/pharmacokinetics , Animals , COVID-19/virology , Cathepsin L/antagonists & inhibitors , Cell Line , Cricetinae , Cysteine Proteinase Inhibitors/pharmacokinetics , Female , Humans , Inhibitory Concentration 50 , Male , Mesocricetus/virology , Reproducibility of Results , SARS-CoV-2/growth & development , Serine Endopeptidases , Substrate Specificity , Virus Replication/drug effects
9.
Signal Transduct Target Ther ; 6(1): 134, 2021 03 27.
Article in English | MEDLINE | ID: covidwho-1152831

ABSTRACT

To discover new drugs to combat COVID-19, an understanding of the molecular basis of SARS-CoV-2 infection is urgently needed. Here, for the first time, we report the crucial role of cathepsin L (CTSL) in patients with COVID-19. The circulating level of CTSL was elevated after SARS-CoV-2 infection and was positively correlated with disease course and severity. Correspondingly, SARS-CoV-2 pseudovirus infection increased CTSL expression in human cells in vitro and human ACE2 transgenic mice in vivo, while CTSL overexpression, in turn, enhanced pseudovirus infection in human cells. CTSL functionally cleaved the SARS-CoV-2 spike protein and enhanced virus entry, as evidenced by CTSL overexpression and knockdown in vitro and application of CTSL inhibitor drugs in vivo. Furthermore, amantadine, a licensed anti-influenza drug, significantly inhibited CTSL activity after SARS-CoV-2 pseudovirus infection and prevented infection both in vitro and in vivo. Therefore, CTSL is a promising target for new anti-COVID-19 drug development.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/metabolism , Cathepsin L , Cysteine Proteinase Inhibitors/pharmacology , Drug Development , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization/drug effects , Adolescent , Adult , Aged , Animals , COVID-19/drug therapy , COVID-19/genetics , Cathepsin L/antagonists & inhibitors , Cathepsin L/genetics , Cathepsin L/metabolism , Female , Humans , Male , Mice , Mice, Transgenic , Middle Aged , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
10.
Sci Rep ; 11(1): 5207, 2021 03 04.
Article in English | MEDLINE | ID: covidwho-1118818

ABSTRACT

The strain SARS-CoV-2, newly emerged in late 2019, has been identified as the cause of COVID-19 and the pandemic declared by WHO in early 2020. Although lipids have been shown to possess antiviral efficacy, little is currently known about lipid compounds with anti-SARS-CoV-2 binding and entry properties. To address this issue, we screened, overall, 17 polyunsaturated fatty acids, monounsaturated fatty acids and saturated fatty acids, as wells as lipid-soluble vitamins. In performing target-based ligand screening utilizing the RBD-SARS-CoV-2 sequence, we observed that polyunsaturated fatty acids most effectively interfere with binding to hACE2, the receptor for SARS-CoV-2. Using a spike protein pseudo-virus, we also found that linolenic acid and eicosapentaenoic acid significantly block the entry of SARS-CoV-2. In addition, eicosapentaenoic acid showed higher efficacy than linolenic acid in reducing activity of TMPRSS2 and cathepsin L proteases, but neither of the fatty acids affected their expression at the protein level. Also, neither reduction of hACE2 activity nor binding to the hACE2 receptor upon treatment with these two fatty acids was observed. Although further in vivo experiments are warranted to validate the current findings, our study provides a new insight into the role of lipids as antiviral compounds against the SARS-CoV-2 strain.


Subject(s)
COVID-19/prevention & control , Fatty Acids, Omega-3/therapeutic use , SARS-CoV-2/drug effects , Virus Attachment/drug effects , Virus Internalization/drug effects , A549 Cells , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/metabolism , Cathepsin L/antagonists & inhibitors , Fatty Acids, Omega-3/pharmacology , Humans , Serine Endopeptidases/drug effects
11.
ACS Infect Dis ; 7(3): 586-597, 2021 03 12.
Article in English | MEDLINE | ID: covidwho-1108883

ABSTRACT

As the COVID-19 pandemic continues to unfold, the morbidity and mortality are increasing daily. Effective treatment for SARS-CoV-2 is urgently needed. We recently discovered four SARS-CoV-2 main protease (Mpro) inhibitors including boceprevir, calpain inhibitors II and XII, and GC-376 with potent antiviral activity against infectious SARS-CoV-2 in cell culture. In this study, we further characterized the mechanism of action of these four compounds using the SARS-CoV-2 pseudovirus neutralization assay. It was found that GC-376 and calpain inhibitors II and XII have a dual mechanism of action by inhibiting both viral Mpro and host cathepsin L in Vero cells. To rule out the cell-type dependent effect, the antiviral activity of these four compounds against SARS-CoV-2 was also confirmed in type 2 transmembrane serine protease-expressing Caco-2 cells using the viral yield reduction assay. In addition, we found that these four compounds have broad-spectrum antiviral activity in inhibiting not only SARS-CoV-2 but also SARS-CoV, and MERS-CoV, as well as human coronaviruses (CoVs) 229E, OC43, and NL63. The mechanism of action is through targeting the viral Mpro, which was supported by the thermal shift-binding assay and enzymatic fluorescence resonance energy transfer assay. We further showed that these four compounds have additive antiviral effect when combined with remdesivir. Altogether, these results suggest that boceprevir, calpain inhibitors II and XII, and GC-376 might be promising starting points for further development against existing human coronaviruses as well as future emerging CoVs.


Subject(s)
Antiviral Agents/pharmacology , Carbonates/pharmacology , Glycoproteins/pharmacology , Leucine/pharmacology , Oligopeptides/pharmacology , Proline/analogs & derivatives , SARS-CoV-2/drug effects , Sulfonic Acids/pharmacology , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Alanine/analogs & derivatives , Alanine/pharmacology , Animals , COVID-19/drug therapy , Caco-2 Cells , Cathepsin L/antagonists & inhibitors , Cell Line , Chlorocebus aethiops , Coronavirus 229E, Human/drug effects , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus NL63, Human/drug effects , Coronavirus OC43, Human/drug effects , Drug Combinations , HEK293 Cells , Humans , Middle East Respiratory Syndrome Coronavirus/drug effects , Proline/pharmacology , Serine Endopeptidases/metabolism , Vero Cells
12.
Curr Top Med Chem ; 21(7): 571-596, 2021.
Article in English | MEDLINE | ID: covidwho-1034909

ABSTRACT

Even after one year of its first outbreak reported in China, the coronavirus disease 2019 (COVID-19) pandemic is still sweeping the World, causing serious infections and claiming more fatalities. COVID-19 is caused by the novel coronavirus SARS-CoV-2, which belongs to the genus Betacoronavirus (ß-CoVs), which is of greatest clinical importance since it contains many other viruses that cause respiratory disease in humans, including OC43, HKU1, SARS-CoV, and MERS. The spike (S) glycoprotein of ß-CoVs is a key virulence factor in determining disease pathogenesis and host tropism, and it also mediates virus binding to the host's receptors to allow viral entry into host cells, i.e., the first step in virus lifecycle. Viral entry inhibitors are considered promising putative drugs for COVID-19. Herein, we mined the biomedical literature for viral entry inhibitors of other coronaviruses, with special emphasis on ß-CoVs entry inhibitors. We also outlined the structural features of SARS-CoV-2 S protein and how it differs from other ß-CoVs to better understand the structural determinants of S protein binding to its human receptor (ACE2). This review highlighted several promising viral entry inhibitors as potential treatments for COVID-19.


Subject(s)
Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Antiviral Agents/chemistry , Protease Inhibitors/chemistry , Receptors, Virus/antagonists & inhibitors , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Virus Internalization/drug effects , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Antiviral Agents/isolation & purification , Antiviral Agents/pharmacology , COVID-19/drug therapy , COVID-19/enzymology , COVID-19/virology , Cathepsin L/antagonists & inhibitors , Cathepsin L/chemistry , Cathepsin L/genetics , Cathepsin L/metabolism , Gene Expression , Humans , Phytochemicals/chemistry , Phytochemicals/isolation & purification , Phytochemicals/pharmacology , Plants, Medicinal/chemistry , Protease Inhibitors/isolation & purification , Protease Inhibitors/pharmacology , Protein Binding , Receptors, Virus/chemistry , Receptors, Virus/genetics , Receptors, Virus/metabolism , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Serine Endopeptidases/chemistry , Serine Endopeptidases/genetics , Serine Endopeptidases/metabolism , Small Molecule Libraries/chemistry , Small Molecule Libraries/isolation & purification , Small Molecule Libraries/pharmacology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Structure-Activity Relationship
14.
Front Cell Infect Microbiol ; 10: 589505, 2020.
Article in English | MEDLINE | ID: covidwho-1000069

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemics is a challenge without precedent for the modern science. Acute Respiratory Discomfort Syndrome (ARDS) is the most common immunopathological event in SARS-CoV-2, SARS-CoV, and MERS-CoV infections. Fast lung deterioration results of cytokine storm determined by a robust immunological response leading to ARDS and multiple organ failure. Here, we show cysteine protease Cathepsin L (CatL) involvement with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and COVID-19 from different points of view. CatL is a lysosomal enzyme that participates in numerous physiological processes, including apoptosis, antigen processing, and extracellular matrix remodeling. CatL is implicated in pathological conditions like invasion and metastasis of tumors, inflammatory status, atherosclerosis, renal disease, diabetes, bone diseases, viral infection, and other diseases. CatL expression is up-regulated during chronic inflammation and is involved in degrading extracellular matrix, an important process for SARS-CoV-2 to enter host cells. In addition, CatL is probably involved in processing SARS-CoV-2 spike protein. As its inhibition is detrimental to SARS-CoV-2 infection and possibly exit from cells during late stages of infection, CatL could have been considered a valuable therapeutic target. Therefore, we describe here some drugs already in the market with potential CatL inhibiting capacity that could be used to treat COVID-19 patients. In addition, we discuss the possible role of host genetics in the etiology and spreading of the disease.


Subject(s)
COVID-19/complications , Cathepsin L/physiology , Pandemics , Respiratory Distress Syndrome/enzymology , SARS-CoV-2/physiology , Acute Kidney Injury/etiology , Amantadine/therapeutic use , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/drug therapy , COVID-19/epidemiology , Cathepsin L/antagonists & inhibitors , Cathepsin L/genetics , Chloroquine/therapeutic use , Cysteine Proteinase Inhibitors/therapeutic use , Genetic Predisposition to Disease , Heparin/therapeutic use , Humans , Hydroxychloroquine/therapeutic use , Lysosomes/enzymology , Molecular Targeted Therapy , Receptors, Virus/metabolism , Respiratory Distress Syndrome/etiology , SARS-CoV-2/ultrastructure , Serine Endopeptidases/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Teicoplanin/therapeutic use , Virus Internalization
15.
Sci Adv ; 6(50)2020 12.
Article in English | MEDLINE | ID: covidwho-969082

ABSTRACT

The main protease (Mpro) of SARS-CoV-2 is a key antiviral drug target. While most Mpro inhibitors have a γ-lactam glutamine surrogate at the P1 position, we recently found that several Mpro inhibitors have hydrophobic moieties at the P1 site, including calpain inhibitors II and XII, which are also active against human cathepsin L, a host protease that is important for viral entry. In this study, we solved x-ray crystal structures of Mpro in complex with calpain inhibitors II and XII and three analogs of GC-376 The structure of Mpro with calpain inhibitor II confirmed that the S1 pocket can accommodate a hydrophobic methionine side chain, challenging the idea that a hydrophilic residue is necessary at this position. The structure of calpain inhibitor XII revealed an unexpected, inverted binding pose. Together, the biochemical, computational, structural, and cellular data presented herein provide new directions for the development of dual inhibitors as SARS-CoV-2 antivirals.


Subject(s)
Cathepsin L/chemistry , Coronavirus 3C Proteases/chemistry , Drug Design , Molecular Dynamics Simulation , Protease Inhibitors/chemistry , Animals , Caco-2 Cells , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Cell Line , Cell Line, Tumor , Chlorocebus aethiops , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/metabolism , Crystallography, X-Ray , Dogs , Humans , Kinetics , Madin Darby Canine Kidney Cells , Models, Chemical , Molecular Structure , Protease Inhibitors/metabolism , Protease Inhibitors/pharmacology , Protein Domains , Vero Cells
16.
Eur J Pharmacol ; 885: 173499, 2020 Oct 15.
Article in English | MEDLINE | ID: covidwho-959755

ABSTRACT

The entry of SARS-CoV-2 into host cells proceeds by a proteolysis process, which involves the lysosomal peptidase cathepsin L. Inhibition of cathepsin L is therefore considered an effective method to decrease the virus internalization. Analysis from the perspective of structure-functionality elucidates that cathepsin L inhibitory proteins/peptides found in food share specific features: multiple disulfide crosslinks (buried in protein core), lack or low contents of (small) α-helices, and high surface hydrophobicity. Lactoferrin can inhibit cathepsin L, but not cathepsins B and H. This selective inhibition might be useful in fine targeting of cathepsin L. Molecular docking indicated that only the carboxyl-terminal lobe of lactoferrin interacts with cathepsin L and that the active site cleft of cathepsin L is heavily superposed by lactoferrin. A controlled proteolysis process might yield lactoferrin-derived peptides that strongly inhibit cathepsin L.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Betacoronavirus/physiology , Cathepsin L/antagonists & inhibitors , Food , Lactoferrin/pharmacology , Protease Inhibitors/pharmacology , Antiviral Agents/chemistry , Lactoferrin/chemistry , Protease Inhibitors/chemistry , SARS-CoV-2 , Virus Internalization/drug effects
17.
Molecules ; 25(17)2020 Aug 22.
Article in English | MEDLINE | ID: covidwho-727433

ABSTRACT

Presently, there are no approved drugs or vaccines to treat COVID-19, which has spread to over 200 countries and at the time of writing was responsible for over 650,000 deaths worldwide. Recent studies have shown that two human proteases, TMPRSS2 and cathepsin L, play a key role in host cell entry of SARS-CoV-2. Importantly, inhibitors of these proteases were shown to block SARS-CoV-2 infection. Here, we perform virtual screening of 14,011 phytochemicals produced by Indian medicinal plants to identify natural product inhibitors of TMPRSS2 and cathepsin L. AutoDock Vina was used to perform molecular docking of phytochemicals against TMPRSS2 and cathepsin L. Potential phytochemical inhibitors were filtered by comparing their docked binding energies with those of known inhibitors of TMPRSS2 and cathepsin L. Further, the ligand binding site residues and non-covalent interactions between protein and ligand were used as an additional filter to identify phytochemical inhibitors that either bind to or form interactions with residues important for the specificity of the target proteases. This led to the identification of 96 inhibitors of TMPRSS2 and 9 inhibitors of cathepsin L among phytochemicals of Indian medicinal plants. Further, we have performed molecular dynamics (MD) simulations to analyze the stability of the protein-ligand complexes for the three top inhibitors of TMPRSS2 namely, qingdainone, edgeworoside C and adlumidine, and of cathepsin L namely, ararobinol, (+)-oxoturkiyenine and 3α,17α-cinchophylline. Interestingly, several herbal sources of identified phytochemical inhibitors have antiviral or anti-inflammatory use in traditional medicine. Further in vitro and in vivo testing is needed before clinical trials of the promising phytochemical inhibitors identified here.


Subject(s)
Antiviral Agents/chemistry , Betacoronavirus/drug effects , Cathepsin L/chemistry , Phytochemicals/chemistry , Protease Inhibitors/chemistry , Receptors, Virus/chemistry , Serine Endopeptidases/chemistry , Amino Acid Sequence , Antiviral Agents/isolation & purification , Antiviral Agents/pharmacology , Betacoronavirus/pathogenicity , Binding Sites , COVID-19 , Cathepsin L/antagonists & inhibitors , Cathepsin L/genetics , Cathepsin L/metabolism , Coronavirus Infections/drug therapy , Coronavirus Infections/enzymology , Coronavirus Infections/virology , Coumarins/chemistry , Coumarins/isolation & purification , Coumarins/pharmacology , Gene Expression , High-Throughput Screening Assays , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Humans , India , Molecular Docking Simulation , Molecular Dynamics Simulation , Monosaccharides/chemistry , Monosaccharides/isolation & purification , Monosaccharides/pharmacology , Pandemics , Phytochemicals/isolation & purification , Phytochemicals/pharmacology , Plants, Medicinal/chemistry , Pneumonia, Viral/drug therapy , Pneumonia, Viral/enzymology , Pneumonia, Viral/virology , Protease Inhibitors/isolation & purification , Protease Inhibitors/pharmacology , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Quinazolines/chemistry , Quinazolines/isolation & purification , Quinazolines/pharmacology , Receptors, Virus/antagonists & inhibitors , Receptors, Virus/genetics , Receptors, Virus/metabolism , SARS-CoV-2 , Serine Endopeptidases/genetics , Serine Endopeptidases/metabolism , Thermodynamics , Virus Internalization/drug effects
18.
Int J Antimicrob Agents ; 56(3): 106119, 2020 Sep.
Article in English | MEDLINE | ID: covidwho-690298

ABSTRACT

Coronavirus disease 2019 (COVID-19) is a highly transmissible viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical trials have reported improved outcomes resulting from an effective reduction or absence of viral load when patients were treated with chloroquine (CQ) or hydroxychloroquine (HCQ). In addition, the effects of these drugs were improved by simultaneous administration of azithromycin (AZM). The receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein binds to the cell surface angiotensin-converting enzyme 2 (ACE2) receptor, allowing virus entry and replication in host cells. The viral main protease (Mpro) and host cathepsin L (CTSL) are among the proteolytic systems involved in SARS-CoV-2 S protein activation. Hence, molecular docking studies were performed to test the binding performance of these three drugs against four targets. The findings showed AZM affinity scores (ΔG) with strong interactions with ACE2, CTSL, Mpro and RBD. CQ affinity scores showed three low-energy results (less negative) with ACE2, CTSL and RBD, and a firm bond score with Mpro. For HCQ, two results (ACE2 and Mpro) were firmly bound to the receptors, however CTSL and RBD showed low interaction energies. The differences in better interactions and affinity between HCQ and CQ with ACE2 and Mpro were probably due to structural differences between the drugs. On other hand, AZM not only showed more negative (better) values in affinity, but also in the number of interactions in all targets. Nevertheless, further studies are needed to investigate the antiviral properties of these drugs against SARS-CoV-2.


Subject(s)
Antiviral Agents/pharmacology , Azithromycin/chemistry , Betacoronavirus/chemistry , Cathepsin L/chemistry , Chloroquine/chemistry , Cysteine Endopeptidases/chemistry , Hydroxychloroquine/chemistry , Peptidyl-Dipeptidase A/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Viral Nonstructural Proteins/chemistry , Amino Acid Motifs , Angiotensin-Converting Enzyme 2 , Antiviral Agents/chemistry , Azithromycin/pharmacology , Betacoronavirus/metabolism , Binding Sites , COVID-19 , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Chloroquine/pharmacology , Coronavirus 3C Proteases , Coronavirus Infections/drug therapy , Coronavirus Infections/virology , Cysteine Endopeptidases/metabolism , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Humans , Hydroxychloroquine/pharmacology , Molecular Docking Simulation , Pandemics , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/drug therapy , Pneumonia, Viral/virology , Protein Binding , Protein Interaction Domains and Motifs , Protein Structure, Secondary , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Thermodynamics , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism , Virus Attachment/drug effects
19.
J Med Chem ; 63(21): 12256-12274, 2020 11 12.
Article in English | MEDLINE | ID: covidwho-598389

ABSTRACT

Recently, a novel coronavirus initially designated 2019-nCoV but now termed SARS-CoV-2 has emerged and raised global concerns due to its virulence. SARS-CoV-2 is the etiological agent of "coronavirus disease 2019", abbreviated to COVID-19, which despite only being identified at the very end of 2019, has now been classified as a pandemic by the World Health Organization (WHO). At this time, no specific prophylactic or postexposure therapy for COVID-19 are currently available. Viral entry is the first step in the SARS-CoV-2 lifecycle and is mediated by the trimeric spike protein. Being the first stage in infection, entry of SARS-CoV-2 into host cells is an extremely attractive therapeutic intervention point. Within this review, we highlight therapeutic intervention strategies for anti-SARS-CoV, MERS-CoV, and other coronaviruses and speculate upon future directions for SARS-CoV-2 entry inhibitor designs.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/drug therapy , SARS-CoV-2/drug effects , Virus Internalization/drug effects , Amino Acid Sequence , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/metabolism , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Animals , COVID-19/prevention & control , Cathepsin L/antagonists & inhibitors , Cell Line , Humans , Protein Domains , Spike Glycoprotein, Coronavirus/antagonists & inhibitors
20.
Pharmacol Ther ; 213: 107587, 2020 09.
Article in English | MEDLINE | ID: covidwho-381913

ABSTRACT

The widespread coronavirus SARS-CoV-2 has already infected over 4 million people worldwide, with a death toll over 280,000. Current treatment of COVID-19 patients relies mainly on antiviral drugs lopinavir/ritonavir, arbidol, and remdesivir, the anti-malarial drugs hydroxychloroquine and chloroquine, and traditional Chinese medicine. There are over 2,118 on-going clinical trials underway, but to date none of these drugs have consistently proven effective. Cathepsin L (CatL) is an endosomal cysteine protease. It mediates the cleavage of the S1 subunit of the coronavirus surface spike glycoprotein. This cleavage is necessary for coronavirus entry into human host cells, virus and host cell endosome membrane fusion, and viral RNA release for next round of replication. Here we summarize data regarding seven CatL-selective inhibitors that block coronavirus entry into cultured host cells and provide a mechanism to block SARS-CoV-2 infection in humans. Given the rapid growth of the SARS-CoV-2-positive population worldwide, ready-to-use CatL inhibitors should be explored as a treatment option. We identify ten US FDA-approved drugs that have CatL inhibitory activity. We provide evidence that supports the combined use of serine protease and CatL inhibitors as a possibly safer and more effective therapy than other available therapeutics to block coronavirus host cell entry and intracellular replication, without compromising the immune system.


Subject(s)
Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , Cathepsin L/antagonists & inhibitors , Coronavirus Infections/drug therapy , Coronavirus Infections/physiopathology , Pneumonia, Viral/drug therapy , Pneumonia, Viral/physiopathology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Antigen-Presenting Cells/metabolism , Antimalarials/pharmacology , Antimalarials/therapeutic use , Antiviral Agents/administration & dosage , Antiviral Agents/adverse effects , Betacoronavirus , COVID-19 , Clinical Trials as Topic/statistics & numerical data , Dose-Response Relationship, Drug , Drug Approval , Drug Therapy, Combination , Humans , Immunologic Factors/pharmacology , Immunologic Factors/therapeutic use , Medicine, Chinese Traditional/methods , Pandemics , SARS-CoV-2 , Serine Endopeptidases/metabolism , United States , United States Food and Drug Administration
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