1
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Khatua K, Alugubelli YR, Yang KS, Vulupala VR, Blankenship LR, Coleman D, Atla S, Chaki SP, Geng ZZ, Ma XR, Xiao J, Chen PH, Cho CCD, Sharma S, Vatansever EC, Ma Y, Yu G, Neuman BW, Xu S, Liu WR. Azapeptides with unique covalent warheads as SARS-CoV-2 main protease inhibitors. Antiviral Res 2024; 225:105874. [PMID: 38555023 PMCID: PMC11070182 DOI: 10.1016/j.antiviral.2024.105874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/16/2024] [Accepted: 03/25/2024] [Indexed: 04/02/2024]
Abstract
The main protease (MPro) of SARS-CoV-2, the causative agent of COVID-19, is a pivotal nonstructural protein critical for viral replication and pathogenesis. Its protease function relies on three active site pockets for substrate recognition and a catalytic cysteine for enzymatic activity. To develop potential SARS-CoV-2 antivirals, we successfully synthesized a diverse range of azapeptide inhibitors with various covalent warheads to target MPro's catalytic cysteine. Our characterization identified potent MPro inhibitors, including MPI89 that features an aza-2,2-dichloroacetyl warhead with a remarkable EC50 value of 10 nM against SARS-CoV-2 infection in ACE2+ A549 cells and a selective index of 875. MPI89 is also remarkably selective and shows no potency against SARS-CoV-2 papain-like protease and several human proteases. Crystallography analyses demonstrated that these inhibitors covalently engaged the catalytic cysteine and used the aza-amide carbonyl oxygen to bind to the oxyanion hole. MPI89 stands as one of the most potent MPro inhibitors, suggesting the potential for further exploration of azapeptides and the aza-2,2-dichloroacetyl warhead for developing effective therapeutics against COVID-19.
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Affiliation(s)
- Kaustav Khatua
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Yugendar R Alugubelli
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Kai S Yang
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Veerabhadra R Vulupala
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Lauren R Blankenship
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Demonta Coleman
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Sandeep Atla
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Sankar P Chaki
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Zhi Zachary Geng
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Xinyu R Ma
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Jing Xiao
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Peng-Hsun Chen
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Chia-Chuan D Cho
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Shivangi Sharma
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Erol C Vatansever
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Yuying Ma
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Ge Yu
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA
| | - Benjamin W Neuman
- Department of Biology, Texas A&M University, College Station, TX 77843, USA; Texas A&M Global Health Research Complex, Texas A&M University, College Station, TX 77843, USA; Health Science Centre, Department of Molecular Pathogenesis and Immunology, Texas A&M University, College Station, TX 77843, USA
| | - Shiqing Xu
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA; Department of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M University, College Station, TX 77843, USA.
| | - Wenshe Ray Liu
- Texas A&M Drug Discovery Center and Department of Chemistry, Texas A&M University, College Station, TX 77854, USA; Department of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M University, College Station, TX 77843, USA; Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX 77030, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA; Department of Cell Biology and Genetics, College of Medicine, Texas A&M University, College Station, TX 77843, USA.
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2
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Alugubelli Y, Xiao J, Khatua K, Kumar S, Sun L, Ma Y, Ma XR, Vulupala VR, Atla S, Blankenship LR, Coleman D, Xie X, Neuman BW, Liu WR, Xu S. Discovery of First-in-Class PROTAC Degraders of SARS-CoV-2 Main Protease. J Med Chem 2024; 67:6495-6507. [PMID: 38608245 PMCID: PMC11056980 DOI: 10.1021/acs.jmedchem.3c02416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/14/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024]
Abstract
We have witnessed three coronavirus (CoV) outbreaks in the past two decades, including the COVID-19 pandemic caused by SARS-CoV-2. Main protease (MPro), a highly conserved protease among various CoVs, is essential for viral replication and pathogenesis, making it a prime target for antiviral drug development. Here, we leverage proteolysis targeting chimera (PROTAC) technology to develop a new class of small-molecule antivirals that induce the degradation of SARS-CoV-2 MPro. Among them, MPD2 was demonstrated to effectively reduce MPro protein levels in 293T cells, relying on a time-dependent, CRBN-mediated, and proteasome-driven mechanism. Furthermore, MPD2 exhibited remarkable efficacy in diminishing MPro protein levels in SARS-CoV-2-infected A549-ACE2 cells. MPD2 also displayed potent antiviral activity against various SARS-CoV-2 strains and exhibited enhanced potency against nirmatrelvir-resistant viruses. Overall, this proof-of-concept study highlights the potential of targeted protein degradation of MPro as an innovative approach for developing antivirals that could fight against drug-resistant viral variants.
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Affiliation(s)
- Yugendar
R. Alugubelli
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Jing Xiao
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Kaustav Khatua
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Sathish Kumar
- Department
of Biology, Texas A&M University, College Station, Texas 77843, United States
| | - Long Sun
- Department
of Biochemistry & Molecular Biology, The University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Yuying Ma
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Xinyu R. Ma
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Veerabhadra R. Vulupala
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Sandeep Atla
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Lauren R. Blankenship
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Demonta Coleman
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Xuping Xie
- Department
of Biochemistry & Molecular Biology, The University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Benjamin W. Neuman
- Department
of Biology, Texas A&M University, College Station, Texas 77843, United States
- Texas
A&M Global Health Research Complex, Texas A&M University, College
Station, Texas 77843, United States
| | - Wenshe Ray Liu
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Department
of Biochemistry and Biophysics, Texas A&M
University, College Station, Texas 77843, United States
- Institute
of Biosciences and Technology and Department of Translational Medical
Sciences, College of Medicine, Texas A&M
University, Houston, Texas 77030, United States
- Department
of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, Texas 77843, United States
| | - Shiqing Xu
- Texas
A&M Drug Discovery Center, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Department
of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M University, College Station, Texas 77843, United States
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3
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Geng ZZ, Atla S, Shaabani N, Vulupala V, Yang KS, Alugubelli YR, Khatua K, Chen PH, Xiao J, Blankenship LR, Ma XR, Vatansever EC, Cho CCD, Ma Y, Allen R, Ji H, Xu S, Liu WR. A Systematic Survey of Reversibly Covalent Dipeptidyl Inhibitors of the SARS-CoV-2 Main Protease. J Med Chem 2023; 66:11040-11055. [PMID: 37561993 PMCID: PMC10861299 DOI: 10.1021/acs.jmedchem.3c00221] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Indexed: 08/12/2023]
Abstract
SARS-CoV-2, the COVID-19 pathogen, relies on its main protease (MPro) for replication and pathogenesis. MPro is a demonstrated target for the development of antivirals for SARS-CoV-2. Past studies have systematically explored tripeptidyl inhibitors such as nirmatrelvir as MPro inhibitors. However, dipeptidyl inhibitors especially those with a spiro residue at their P2 position have not been systematically investigated. In this work, we synthesized about 30 dipeptidyl MPro inhibitors and characterized them on enzymatic inhibition potency, structures of their complexes with MPro, cellular MPro inhibition potency, antiviral potency, cytotoxicity, and in vitro metabolic stability. Our results indicated that MPro has a flexible S2 pocket to accommodate inhibitors with a large P2 residue and revealed that dipeptidyl inhibitors with a large P2 spiro residue such as (S)-2-azaspiro [4,4]nonane-3-carboxylate and (S)-2-azaspiro[4,5]decane-3-carboxylate have favorable characteristics. One compound, MPI60, containing a P2 (S)-2-azaspiro[4,4]nonane-3-carboxylate displayed high antiviral potency, low cellular cytotoxicity, and high in vitro metabolic stability.
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Affiliation(s)
- Zhi Zachary Geng
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Sandeep Atla
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Namir Shaabani
- Sorrento
Therapeutics, Inc. San Diego, California 92121, United States
| | - Veerabhadra Vulupala
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Kai S. Yang
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Yugendar R. Alugubelli
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Kaustav Khatua
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Peng-Hsun Chen
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Jing Xiao
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Lauren R. Blankenship
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Xinyu R. Ma
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Erol C. Vatansever
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Chia-Chuan D. Cho
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Yuying Ma
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
| | - Robert Allen
- Sorrento
Therapeutics, Inc. San Diego, California 92121, United States
| | - Henry Ji
- Sorrento
Therapeutics, Inc. San Diego, California 92121, United States
| | - Shiqing Xu
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
- Department
of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M University, College Station, Texas 77843, United States
| | - Wenshe Ray Liu
- Department
of Chemistry, Texas A&M Drug Discovery Laboratory, Texas A&M University, College Station, Texas 77843, United States
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
- Institute
of Biosciences and Technology and Department of Translational Medical
Sciences, College of Medicine, Texas A&M
University, Houston, Texas 77030, United States
- Department
of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, Texas 77843, United States
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4
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Khatua K, Alugubelli YR, Yang KS, Vulupala VR, Blankenship LR, Coleman DD, Atla S, Chaki SP, Geng ZZ, Ma XR, Xiao J, Chen PHC, Cho CCD, Vatansever EC, Ma Y, Yu G, Neuman BW, Xu S, Liu WR. An Azapeptide Platform in Conjunction with Covalent Warheads to Uncover High-Potency Inhibitors for SARS-CoV-2 Main Protease. bioRxiv 2023:2023.04.11.536467. [PMID: 37090597 PMCID: PMC10120698 DOI: 10.1101/2023.04.11.536467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Main protease (M Pro ) of SARS-CoV-2, the viral pathogen of COVID-19, is a crucial nonstructural protein that plays a vital role in the replication and pathogenesis of the virus. Its protease function relies on three active site pockets to recognize P1, P2, and P4 amino acid residues in a substrate and a catalytic cysteine residue for catalysis. By converting the P1 Cα atom in an M Pro substrate to nitrogen, we showed that a large variety of azapeptide inhibitors with covalent warheads targeting the M Pro catalytic cysteine could be easily synthesized. Through the characterization of these inhibitors, we identified several highly potent M Pro inhibitors. Specifically, one inhibitor, MPI89 that contained an aza-2,2-dichloroacetyl warhead, displayed a 10 nM EC 50 value in inhibiting SARS-CoV-2 from infecting ACE2 + A549 cells and a selectivity index of 875. The crystallography analyses of M Pro bound with 6 inhibitors, including MPI89, revealed that inhibitors used their covalent warheads to covalently engage the catalytic cysteine and the aza-amide carbonyl oxygen to bind to the oxyanion hole. MPI89 represents one of the most potent M Pro inhibitors developed so far, suggesting that further exploration of the azapeptide platform and the aza-2,2-dichloroacetyl warhead is needed for the development of potent inhibitors for the SARS-CoV-2 M Pro as therapeutics for COVID-19.
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5
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Yang KS, Blankenship LR, Kuo STA, Sheng YJ, Li P, Fierke CA, Russell DH, Yan X, Xu S, Liu WR. A Novel Y-Shaped, S-O-N-O-S-Bridged Cross-Link between Three Residues C22, C44, and K61 Is Frequently Observed in the SARS-CoV-2 Main Protease. ACS Chem Biol 2023; 18:449-455. [PMID: 36629751 PMCID: PMC10023456 DOI: 10.1021/acschembio.2c00695] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
As the COVID-19 pathogen, SARS-CoV-2 relies on its main protease (MPro) for pathogenesis and replication. During crystallographic analyses of MPro crystals that were exposed to the air, a uniquely Y-shaped, S-O-N-O-S-bridged post-translational cross-link that connects three residues C22, C44, and K61 at their side chains was frequently observed. As a novel covalent modification, this cross-link serves potentially as a redox switch to regulate the catalytic activity of MPro, a demonstrated drug target of COVID-19. The formation of this linkage leads to a much more open active site that can potentially be targeted for the development of novel SARS-CoV-2 antivirals. The structural rearrangement of MPro by this cross-link indicates that small molecules that lock MPro in the cross-linked form can potentially be used with other active-site-targeting molecules such as paxlovid for synergistic effects in inhibiting SARS-CoV-2 viral replication.
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Affiliation(s)
- Kai S. Yang
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | | | - Syuan-Ting Alex Kuo
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Yan J. Sheng
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Carol A. Fierke
- Department of Biochemistry, Brandeis University, Waltham, MA 02453, USA
| | - David H. Russell
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Xin Yan
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Shiqing Xu
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
- Irma Lerma Rangel College of Pharmacy, Texas A&M University, College Station, TX 77843, USA
| | - Wenshe Ray Liu
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
- Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX 77030, USA
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6
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Geng ZZ, Atla S, Shaabani N, Vulupala VR, Yang KS, Alugubelli YR, Khatua K, Chen PHC, Xiao J, Blankenship LR, Ma XR, Vatansever EC, Cho CC, Ma Y, Allen R, Ji H, Xu S, Liu WR. A Systematic Survey of Reversibly Covalent Dipeptidyl Inhibitors of the SARS-CoV-2 Main Protease. bioRxiv 2023:2023.01.17.524469. [PMID: 36711580 PMCID: PMC9882326 DOI: 10.1101/2023.01.17.524469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
SARS-CoV-2 is the coronavirus pathogen of the currently prevailing COVID-19 pandemic. It relies on its main protease (M Pro ) for replication and pathogenesis. M Pro is a demonstrated target for the development of antivirals for SARS-CoV-2. Past studies have systematically explored tripeptidyl inhibitors such as nirmatrelvir as M Pro inhibitors. However, dipeptidyl inhibitors especially those with a spiro residue at their P2 position have not been systematically investigated. In this work, we synthesized about 30 reversibly covalent dipeptidyl M Pro inhibitors and characterized them on in vitro enzymatic inhibition potency, structures of their complexes with M Pro , cellular M Pro inhibition potency, antiviral potency, cytotoxicity, and in vitro metabolic stability. Our results indicated that M Pro has a flexible S2 pocket that accommodates dipeptidyl inhibitors with a large P2 residue and revealed that dipeptidyl inhibitors with a large P2 spiro residue such as ( S )-2-azaspiro[4,4]nonane-3-carboxylate and ( S )-2-azaspiro[4,5]decane-3-carboxylate have optimal characteristics. One compound MPI60 containing a P2 ( S )-2-azaspiro[4,4]nonane-3-carboxylate displayed high antiviral potency, low cellular cytotoxicity, and high in vitro metabolic stability and can be potentially advanced to further preclinical tests.
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7
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Alugubelli YR, Geng ZZ, Yang KS, Shaabani N, Khatua K, Ma XR, Vatansever EC, Cho CC, Ma Y, Xiao J, Blankenship LR, Yu G, Sankaran B, Li P, Allen R, Ji H, Xu S, Liu WR. A systematic exploration of boceprevir-based main protease inhibitors as SARS-CoV-2 antivirals. Eur J Med Chem 2022; 240:114596. [PMID: 35839690 PMCID: PMC9264725 DOI: 10.1016/j.ejmech.2022.114596] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/29/2022] [Accepted: 07/05/2022] [Indexed: 01/13/2023]
Abstract
Boceprevir is an HCV NSP3 inhibitor that was explored as a repurposed drug for COVID-19. It inhibits the SARS-CoV-2 main protease (MPro) and contains an α-ketoamide warhead, a P1 β-cyclobutylalanyl moiety, a P2 dimethylcyclopropylproline, a P3 tert-butylglycine, and a P4 N-terminal tert-butylcarbamide. By introducing modifications at all four positions, we synthesized 20 boceprevir-based MPro inhibitors including PF-07321332 and characterized their MPro inhibition potency in test tubes (in vitro) and 293T cells (in cellulo). Crystal structures of MPro bound with 10 inhibitors and cytotoxicity and antiviral potency of 4 inhibitors were characterized as well. Replacing the P1 site with a β-(S-2-oxopyrrolidin-3-yl)-alanyl (Opal) residue and the warhead with an aldehyde leads to high in vitro potency. The original moieties at P2, P3 and the P4 N-terminal cap positions in boceprevir are better than other tested chemical moieties for high in vitro potency. In crystal structures, all inhibitors form a covalent adduct with the MPro active site cysteine. The P1 Opal residue, P2 dimethylcyclopropylproline and P4 N-terminal tert-butylcarbamide make strong hydrophobic interactions with MPro, explaining high in vitro potency of inhibitors that contain these moieties. A unique observation was made with an inhibitor that contains a P4 N-terminal isovaleramide. In its MPro complex structure, the P4 N-terminal isovaleramide is tucked deep in a small pocket of MPro that originally recognizes a P4 alanine side chain in a substrate. Although all inhibitors show high in vitro potency, they have drastically different in cellulo potency to inhibit ectopically expressed MPro in human 293T cells. In general, inhibitors with a P4 N-terminal carbamide or amide have low in cellulo potency. This trend is reversed when the P4 N-terminal cap is changed to a carbamate. The installation of a P3 O-tert-butyl-threonine improves in cellulo potency. Three molecules that contain a P4 N-terminal carbamate were advanced to cytotoxicity tests on 293T cells and antiviral potency tests on three SARS-CoV-2 variants. They all have relatively low cytotoxicity and high antiviral potency with EC50 values around 1 μM. A control compound with a nitrile warhead and a P4 N-terminal amide has undetectable antiviral potency. Based on all observations, we conclude that a P4 N-terminal carbamate in a boceprevir derivative is key for high antiviral potency against SARS-CoV-2.
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Affiliation(s)
- Yugendar R Alugubelli
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Zhi Zachary Geng
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Kai S Yang
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | | | - Kaustav Khatua
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Xinyu R Ma
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Erol C Vatansever
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Chia-Chuan Cho
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Yuying Ma
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Jing Xiao
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Lauren R Blankenship
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Ge Yu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Laurence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Robert Allen
- Sorrento Therapeutics, Inc. San Diego, CA, 92121, USA
| | - Henry Ji
- Sorrento Therapeutics, Inc. San Diego, CA, 92121, USA.
| | - Shiqing Xu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA.
| | - Wenshe Ray Liu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA; Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX, 77030, USA; Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX, 77843, USA.
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8
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Yang KS, Alex Kuo ST, Blankenship LR, Geng ZZ, Li SG, Russell DH, Yan X, Xu S, Liu WR. Repurposing Halicin as a potent covalent inhibitor for the SARS-CoV-2 main protease. Curr Res Chem Biol 2022; 2:100025. [PMID: 35815070 PMCID: PMC9023366 DOI: 10.1016/j.crchbi.2022.100025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/30/2022] [Accepted: 04/07/2022] [Indexed: 12/14/2022]
Abstract
The rapid spread of COVID-19 has caused a worldwide public health crisis. For prompt and effective development of antivirals for SARS-CoV-2, the pathogen of COVID-19, drug repurposing has been broadly conducted by targeting the main protease (MPro), a key enzyme responsible for the replication of virus inside the host. In this study, we evaluate the inhibition potency of a nitrothiazole-containing drug, halicin, and reveal its reaction and interaction mechanism with MPro. The in vitro potency test shows that halicin inhibits the activity of MPro an IC50 of 181.7 nM. Native mass spectrometry and X-ray crystallography studies clearly indicate that the nitrothiazole fragment of halicin covalently binds to the catalytic cysteine C145 of MPro. Interaction and conformational changes inside the active site of MPro suggest a favorable nucleophilic aromatic substitution reaction mechanism between MPro C145 and halicin, explaining the high inhibition potency of halicin towards MPro.
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Affiliation(s)
- Kai S Yang
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Syuan-Ting Alex Kuo
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Lauren R Blankenship
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Zhi Zachary Geng
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Shuhua G Li
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - David H Russell
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Xin Yan
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Shiqing Xu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Wenshe Ray Liu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
- Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX, 77030, USA
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX, 77843, USA
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9
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Li SG, Yang KS, Blankenship LR, Cho CCD, Xu S, Wang H, Liu WR. An Enhanced Hybrid Screening Approach to Identify Potent Inhibitors for the SARS-CoV-2 Main Protease From the NCI Compound Library. Front Chem 2022; 10:816576. [PMID: 35252116 PMCID: PMC8892251 DOI: 10.3389/fchem.2022.816576] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/28/2022] [Indexed: 12/20/2022] Open
Abstract
The emergence and rapid spread of SARS-CoV-2, the pathogen of COVID-19, have caused a worldwide public health crisis. The SARS-CoV-2 main protease (Mpro) is an essential enzyme for the virus and therefore an appealing target for the development of antivirals to treat COVID-19 patients. Recently, many in silico screenings have been performed against the main protease to discover novel hits. However, the actual hit rate of virtual screening is often low, and most of the predicted compounds are false positive hits. In this study, we developed a refined virtual screening strategy that incorporated molecular docking and post-docking filtering based on parameters including molecular weight and surface area, aiming to achieve predictions with fewer false positive hits. We applied this strategy to the NCI library containing 284,176 compounds against Mpro. In vitro potency analyses validated several potent inhibitors and thus confirmed the feasibility of our virtual screening strategy. Overall, The study resulted in several potent hit Mpro inhibitors, in which two inhibitors have IC50 values below 1 μM, that are worth being further optimized and explored. Meanwhile, the refined virtual screen strategy is also applicable to improve general in silico screening hit rates and is useful to accelerate drug discovery for treating COVID-19 and other viral infections.
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Affiliation(s)
- Shuhua G. Li
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
| | - Kai S. Yang
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
| | - Lauren R. Blankenship
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
| | - Chia-Chuan D. Cho
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
| | - Shiqing Xu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
- *Correspondence: Shiqing Xu, ; Hongbin Wang, ; Wenshe Ray Liu,
| | - Hongbin Wang
- Center for Biomedical Informatics, College of Medicine, Texas A&M University, Houston, TX, United States
- *Correspondence: Shiqing Xu, ; Hongbin Wang, ; Wenshe Ray Liu,
| | - Wenshe Ray Liu
- Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, United States
- Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX, United States
- *Correspondence: Shiqing Xu, ; Hongbin Wang, ; Wenshe Ray Liu,
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10
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Dean Cho CC, Blankenship LR, Ma X, Xu S, Liu W. The Pyrrolysyl-tRNA Synthetase Activity can be Improved by a P188 Mutation that Stabilizes the Full-Length Enzyme. J Mol Biol 2022; 434:167453. [PMID: 35033561 PMCID: PMC9018550 DOI: 10.1016/j.jmb.2022.167453] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 12/18/2021] [Accepted: 01/09/2022] [Indexed: 11/24/2022]
Abstract
The amber suppression-based noncanonical amino acid (ncAA) mutagenesis technique has been widely used in both basic and applied research. So far more than two hundred ncAAs have been genetically encoded by amber codon in both prokaryotes and eukaryotes using wild-type and engineered pyrrolysyl-tRNA synthetase (PylRS)-tRNAPyl (PylT) pairs. Methanosarcina mazei PylRS (MmPylRS) is arguably one of two most used PylRS variants. However, it contains an unstable N-terminal domain that is usually cleaved from the full-length protein during expression and therefore leads to a low enzyme activity. We discovered that the cleavage takes place after A189 and this cleavage is inhibited when MmPylRS is co-expressed with Ca. Methanomethylophilus alvus tRNAPyl (CmaPylT). In the presence of CmaPylT, MmPylRS is cleaved after an alternative site K110. MmPylRS is active toward CmaPylT. Its combined use with CmaPylT leads to enhanced incorporation of Nε-Boc-lysine (BocK) at amber codon. To prevent MmPylRS from cleavage after A189 in the presence of its cognate M. mazei tRNAPyl (MmPylT), we introduced mutations at P188. Our results indicated that the P188G mutation stabilizes MmPylRS. We showed that the P188G mutation in wild-type MmPylRS or its engineered variants allows enhanced incorporation of BocK and other noncanonical amino acids including Nε-acetyl-lysine when they are co-expressed with MmPylT.
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Affiliation(s)
- Chia-Chuan Dean Cho
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Lauren R Blankenship
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Xinyu Ma
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Shiqing Xu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Wenshe Liu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA; Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX 77030, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA; Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843, USA.
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11
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Yu G, Qiao Y, Blankenship LR, Liu WR. Protein Synthesis via Activated Cysteine-Directed Protein Ligation. Methods Mol Biol 2022; 2530:159-167. [PMID: 35761048 DOI: 10.1007/978-1-0716-2489-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Proteins with a functionalized C-terminus are critical to synthesizing large proteins via expressed protein ligation. To overcome the limitations of currently available C-terminus functionalization strategies, we established an approach based on a small molecule cyanylating reagent that chemically activates a cysteine in a recombinant protein at its N-side amide for undergoing nucleophilic acyl substitution with amines. We demonstrated the versatility of this approach by successfully synthesizing RNAse H with its RNA hydrolyzing activity restored and in vitro nucleosome build with a C-terminal posttranslational modified histone H2A. This technique will expand the landscape of protein chemical synthesis and its application in new research fields significantly.
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Affiliation(s)
- Ge Yu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Yuchen Qiao
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Lauren R Blankenship
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Wenshe Ray Liu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX, USA.
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12
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Li L, Chenna BC, Yang KS, Cole TR, Goodall ZT, Giardini M, Moghadamchargari Z, Hernandez EA, Gomez J, Calvet CM, Bernatchez JA, Mellott DM, Zhu J, Rademacher A, Thomas D, Blankenship LR, Drelich A, Laganowsky A, Tseng CTK, Liu WR, Wand AJ, Cruz-Reyes J, Siqueira-Neto JL, Meek TD. Self-Masked Aldehyde Inhibitors: A Novel Strategy for Inhibiting Cysteine Proteases. J Med Chem 2021; 64:11267-11287. [PMID: 34288674 PMCID: PMC10504874 DOI: 10.1021/acs.jmedchem.1c00628] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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.
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Affiliation(s)
- Linfeng Li
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Bala C Chenna
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Kai S Yang
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Taylor R Cole
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Zachary T Goodall
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Miriam Giardini
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, United States
| | - Zahra Moghadamchargari
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Elizabeth A Hernandez
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Jana Gomez
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Claudia M Calvet
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, United States
| | - Jean A Bernatchez
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, United States
| | - Drake M Mellott
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Jiyun Zhu
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Andrew Rademacher
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Diane Thomas
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, United States
| | - Lauren R Blankenship
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Aleksandra Drelich
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Chien-Te K Tseng
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555, United States
| | - Wenshe R Liu
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - A Joshua Wand
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
| | - Jair L Siqueira-Neto
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, United States
| | - Thomas D Meek
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, Texas 77843, United States
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13
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Zhang Z, Ortega D, Rush A, Blankenship LR, Cheng ZJ, Moore RE, Tran MLN, Sandoval LG, Aboulhosn K, Watanabe S, Cortez KS, Perlman DH, Semmelhack MF, Miller Conrad LC. Antibiotic Adjuvant Activity Revealed in a Photoaffinity Approach to Determine the Molecular Target of Antipyocyanin Compounds. ACS Infect Dis 2021; 7:535-543. [PMID: 33587590 DOI: 10.1021/acsinfecdis.0c00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Infections with Pseudomonas aeruginosa are a looming threat to public health. New treatment strategies are needed to combat this pathogen, for example, by blocking the production of virulence factors like pyocyanin. A photoaffinity analogue of an antipyocyanin compound was developed to interrogate the inhibitor's molecular mechanism of action. While we sought to develop antivirulence inhibitors, the proteomics results suggested that the compounds had antibiotic adjuvant activity. Unexpectedly, we found that these compounds amplify the bactericidal activity of colistin, a well-characterized antibiotic, suggesting they may represent a first-in-class antibiotic adjuvant therapy. Analogues have the potential not only to widen the therapeutic index of cationic antimicrobial peptides like colistin, but also to be effective against colistin-resistant strains, strengthening our arsenal to combat P. aeruginosa infections.
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Affiliation(s)
- Zinan Zhang
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Dominic Ortega
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Anthony Rush
- Department of Bioengineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States
| | - Lauren R. Blankenship
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Zi Jun Cheng
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Rebecca E. Moore
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Minh L. N. Tran
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Lucero G. Sandoval
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Kareem Aboulhosn
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Seiichiro Watanabe
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Kendra S. Cortez
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - David H. Perlman
- Princeton Proteomics and Mass Spectrometry Center, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Martin F. Semmelhack
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Laura C. Miller Conrad
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
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14
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Yang KS, Ma XR, Ma Y, Alugubelli YR, Scott DA, Vatansever EC, Drelich AK, Sankaran B, Geng ZZ, Blankenship LR, Ward HE, Sheng YJ, Hsu JC, Kratch KC, Zhao B, Hayatshahi HS, Liu J, Li P, Fierke CA, Tseng CTK, Xu S, Liu WR. A Quick Route to Multiple Highly Potent SARS-CoV-2 Main Protease Inhibitors*. ChemMedChem 2020; 16:942-948. [PMID: 33283984 DOI: 10.1002/cmdc.202000924] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Indexed: 12/23/2022]
Abstract
The COVID-19 pathogen, SARS-CoV-2, requires its main protease (SC2MPro ) to digest two of its translated long polypeptides to form a number of mature proteins that are essential for viral replication and pathogenesis. Inhibition of this vital proteolytic process is effective in preventing the virus from replicating in infected cells and therefore provides a potential COVID-19 treatment option. Guided by previous medicinal chemistry studies about SARS-CoV-1 main protease (SC1MPro ), we have designed and synthesized a series of SC2MPro inhibitors that contain β-(S-2-oxopyrrolidin-3-yl)-alaninal (Opal) for the formation of a reversible covalent bond with the SC2MPro active-site cysteine C145. All inhibitors display high potency with Ki values at or below 100 nM. The most potent compound, MPI3, has as a Ki value of 8.3 nM. Crystallographic analyses of SC2MPro bound to seven inhibitors indicated both formation of a covalent bond with C145 and structural rearrangement from the apoenzyme to accommodate the inhibitors. Virus inhibition assays revealed that several inhibitors have high potency in inhibiting the SARS-CoV-2-induced cytopathogenic effect in both Vero E6 and A549/ACE2 cells. Two inhibitors, MPI5 and MPI8, completely prevented the SARS-CoV-2-induced cytopathogenic effect in Vero E6 cells at 2.5-5 μM and A549/ACE2 cells at 0.16-0.31 μM. Their virus inhibition potency is much higher than that of some existing molecules that are under preclinical and clinical investigations for the treatment of COVID-19. Our study indicates that there is a large chemical space that needs to be explored for the development of SC2MPro inhibitors with ultra-high antiviral potency.
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Affiliation(s)
- Kai S Yang
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Xinyu R Ma
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Yuying Ma
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | | | - Danielle A Scott
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Erol C Vatansever
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Aleksandra K Drelich
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Zhi Z Geng
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Lauren R Blankenship
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Hannah E Ward
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Yan J Sheng
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Jason C Hsu
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Kaci C Kratch
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Baoyu Zhao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Hamed S Hayatshahi
- Department of Pharmaceutical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Jin Liu
- Department of Pharmaceutical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Carol A Fierke
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.,Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Chien-Te K Tseng
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Shiqing Xu
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - Wenshe Ray Liu
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.,Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA.,Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843, USA.,Institute of Biosciences and Technology and Department of Translational Medical Sciences College of Medicine, Texas A&M University, Houston, TX 77030, USA
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15
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Yang KS, Ma XR, Ma Y, Alugubelli YR, Scott DA, Vatansever EC, Drelich AK, Sankaran B, Geng ZZ, Blankenship LR, Ward HE, Sheng YJ, Hsu JC, Kratch KC, Zhao B, Hayatshahi HS, Liu J, Li P, Fierke CA, Tseng CTK, Xu S, Liu WR. A Speedy Route to Multiple Highly Potent SARS-CoV-2 Main Protease Inhibitors. bioRxiv 2020. [PMID: 32766582 DOI: 10.1101/2020.07.28.223784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The COVID-19 pathogen, SARS-CoV-2, requires its main protease (SC2M Pro ) to digest two of its translated polypeptides to form a number of mature proteins that are essential for viral replication and pathogenesis. Inhibition of this vital proteolytic process is effective in preventing the virus from replication in infected cells and therefore provides a potential COVID-19 treatment option. Guided by previous medicinal chemistry studies about SARS-CoV-1 main protease (SC1M Pro ), we have designed and synthesized a series of SC2M Pro inhibitors that contain β-( S -2-oxopyrrolidin-3-yl)-alaninal (Opal) for the formation of a reversible covalent bond with the SC2M Pro active site cysteine C145. All inhibitors display high potency with IC 50 values at or below 100 nM. The most potent compound MPI3 has as an IC 50 value as 8.5 nM. Crystallographic analyses of SC2M Pro bound to 7 inhibitors indicated both formation of a covalent bond with C145 and structural rearrangement from the apoenzyme to accommodate the inhibitors. Virus inhibition assays revealed that several inhibitors have high potency in inhibiting the SARS-CoV-2-induced cytopathogenic effect in both Vero E6 and A549 cells. Two inhibitors MP5 and MPI8 completely prevented the SARS-CoV-2-induced cytopathogenic effect in Vero E6 cells at 2.5-5 μM and A549 cells at 0.16-0.31 μM. Their virus inhibition potency is much higher than some existing molecules that are under preclinical and clinical investigations for the treatment of COVID-19. Our study indicates that there is a large chemical space that needs to be explored for the development of SC2M Pro inhibitors with extreme potency. Due to the urgent matter of the COVID-19 pandemic, MPI5 and MPI8 may be quickly advanced to preclinical and clinical tests for COVID-19.
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16
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Howell M, Dumitrescu DG, Blankenship LR, Herkert D, Hatzios SK. Functional characterization of a subtilisin-like serine protease from Vibrio cholerae. J Biol Chem 2019; 294:9888-9900. [PMID: 31076508 DOI: 10.1074/jbc.ra119.007745] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/07/2019] [Indexed: 11/06/2022] Open
Abstract
Vibrio cholerae, the causative agent of the human diarrheal disease cholera, exports numerous enzymes that facilitate its adaptation to both intestinal and aquatic niches. These secreted enzymes can mediate nutrient acquisition, biofilm assembly, and V. cholerae interactions with its host. We recently identified a V. cholerae-secreted serine protease, IvaP, that is active in V. cholerae-infected rabbits and human choleric stool. IvaP alters the activity of several host and pathogen enzymes in the gut and, along with other secreted V. cholerae proteases, decreases binding of intelectin, an intestinal carbohydrate-binding protein, to V. cholerae in vivo IvaP bears homology to subtilisin-like enzymes, a large family of serine proteases primarily comprised of secreted endopeptidases. Following secretion, IvaP is cleaved at least three times to yield a truncated enzyme with serine hydrolase activity, yet little is known about the mechanism of extracellular maturation. Here, we show that IvaP maturation requires a series of sequential N- and C-terminal cleavage events congruent with the enzyme's mosaic protein domain structure. Using a catalytically inactive reporter protein, we determined that IvaP can be partially processed in trans, but intramolecular proteolysis is most likely required to generate the mature enzyme. Unlike many other subtilisin-like enzymes, the IvaP cleavage pattern is consistent with stepwise processing of the N-terminal propeptide, which could temporarily inhibit, and be cleaved by, the purified enzyme. Furthermore, IvaP was able to cleave purified intelectin, which inhibited intelectin binding to V. cholerae These results suggest that IvaP plays a role in modulating intelectin-V. cholerae interactions.
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Affiliation(s)
- Matthew Howell
- From the Departments of Molecular, Cellular, and Developmental Biology and.,the Microbial Sciences Institute, Yale University, West Haven, Connecticut 06516
| | - Daniel G Dumitrescu
- From the Departments of Molecular, Cellular, and Developmental Biology and.,the Microbial Sciences Institute, Yale University, West Haven, Connecticut 06516.,Chemistry, Yale University, New Haven, Connecticut 06511 and
| | - Lauren R Blankenship
- From the Departments of Molecular, Cellular, and Developmental Biology and.,the Microbial Sciences Institute, Yale University, West Haven, Connecticut 06516
| | - Darby Herkert
- From the Departments of Molecular, Cellular, and Developmental Biology and.,the Microbial Sciences Institute, Yale University, West Haven, Connecticut 06516
| | - Stavroula K Hatzios
- From the Departments of Molecular, Cellular, and Developmental Biology and .,the Microbial Sciences Institute, Yale University, West Haven, Connecticut 06516.,Chemistry, Yale University, New Haven, Connecticut 06511 and
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Akerman GS, Rosenzweig BA, Domon OE, McGarrity LJ, Blankenship LR, Tsai CA, Culp SJ, MacGregor JT, Sistare FD, Chen JJ, Morris SM. Gene expression profiles and genetic damage in benzo(a)pyrene diol epoxide-exposed TK6 cells. Mutat Res 2004; 549:43-64. [PMID: 15120962 DOI: 10.1016/j.mrfmmm.2003.11.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Revised: 11/21/2003] [Accepted: 11/25/2003] [Indexed: 12/23/2022]
Abstract
Microarray analysis is a powerful tool to identify the biological effects of drugs or chemicals on cellular gene expression. In this study, we compare the relationships between traditional measures of genetic toxicology and mutagen-induced alterations in gene expression profiles. TK6 cells were incubated with 0.01, 0.1, or 1.0 microM +/-anti-benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE) for 4 h and then cultured for an additional 20 h. Aliquots of the exposed cells were removed at 4 and 24 h in order to quantify DNA adduct levels by 32P post-labeling and measure cell viability by cloning efficiency and flow cytometry. Gene expression profiles were developed by extracting total RNA from the control and exposed cells at 4 and 24 h, labeling with Cy3 or Cy5 and hybridizing to a human 350 gene array. Mutant frequencies in the Thymidine Kinase and Hypoxanthine Phosphoribosyl Transferase genes were also determined. The 10alpha-(deoxyguanosin-N(2)-yl)-7alpha,8beta,9beta-trihydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene (dG-N(2)-BPDE) adduct increased as a function of dose and was the only adduct identified. A dose-related decrease in cell viability was evident at 24 h, but not at 4 h. Cell death occurred by apoptosis. At 4 h, analysis of the gene expression profiles revealed that Glutathione Peroxidase and Gadd45 were consistently upregulated (greater than 1.5-fold and significantly (P < 0.001) greater than the control in two experiments) in response to 1.0 microM BPDE exposure. Fifteen genes were consistently down-regulated (less than 0.67-fold and significantly (P < 0.001) lower than the control in two experiments) at 4 h in cultures exposed to 1.0 microM BPDE. Genes with altered expression at 4 h included genes important in the progression of the cell-cycle and those that inhibit apoptosis. At 24 h post-exposure, 16 genes, involved in cell-cycle control, detoxification, and apoptosis were consistently upregulated; 10 genes were repressed in cultures exposed to the high dose of BPDE. Real-time quantitative PCR confirmed the differential expression of selected genes. These data suggest that changes in gene expression will help to identify effects of drugs and chemicals on molecular pathways in cells, and will provide useful information about the molecular responses associated with DNA damage. Of the endpoints evaluated, DNA adduct formation was the most sensitive indicator of DNA damage. DNA adduct formation was clearly evident at low doses, but the number of genes with significantly altered expression (P < 0.001) was minimal. Alterations in gene expression were more robust at doses associated with cellular toxicity and induction of mutations.
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Affiliation(s)
- G S Akerman
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
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18
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Manjanatha MG, Shelton SD, Bishop M, Shaddock JG, Dobrovolsky VN, Heflich RH, Webb PJ, Blankenship LR, Beland FA, Greenlees KJ, Culp SJ. Analysis of mutations and bone marrow micronuclei in Big Blue rats fed leucomalachite green. Mutat Res 2004; 547:5-18. [PMID: 15013694 DOI: 10.1016/j.mrfmmm.2003.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2003] [Revised: 11/11/2003] [Accepted: 11/20/2003] [Indexed: 04/29/2023]
Abstract
Leucomalachite green (LMG) is the major metabolite of malachite green (MG), a triphenylmethane dye that has been used widely as an antifungal agent in the fish industry. Concern over MG and LMG is due to the potential for consumer exposure, suggestive evidence of tumor promotion in rodent liver, and suspicion of carcinogenicity based on structure-activity relationships. In order to evaluate the risks associated with exposure to LMG, female Big Blue rats were fed up to 543 ppm LMG; groups of these rats were killed after 4, 16, or 32 weeks of exposure and evaluated for genotoxicity. We previously reported that this treatment resulted in a dose-dependent induction of liver DNA adducts, and that the liver lacI mutant frequency (MF) was increased, but only in rats fed 543 ppm LMG for 16 weeks. In the present study, we report the results from lymphocyte Hprt mutant assays and bone marrow micronucleus assays performed on these same rats. In addition, we have determined the types of lacI mutations induced in the rats fed 543 ppm LMG for 16 weeks and the rats fed control diet. No significant increases in the frequency of micronuclei or Hprt mutants were observed for any of the doses or time points assayed. Molecular analysis of 80 liver lacI mutants from rats fed 543 ppm LMG for 16 weeks revealed that 21% (17/80) were clonal in origin and that most (55/63) of the independent mutations were base pair substitutions. The predominant type of mutation was G:C --> A:T transition (31/63) and the majority (68%) of these involved CpG sites. When corrected for clonality, the 16-week lacI mutation frequency (36 +/- 10) x 10(-6) in treated rats was not significantly different from the clonally corrected control frequency (17 +/- 9 x 10(-6); P = 0.06). Furthermore, the lacI mutational spectrum in treated rats was not significantly different from that found for control rats (P = 0.09). Taken together, these data indicate that the DNA adducts produced by LMG in female rats do not result in detectable levels of genotoxicity, and that the increase in lacI MF observed previously in the liver of treated rats may be due to the disproportionate expansion of spontaneous lacI mutations.
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Affiliation(s)
- M G Manjanatha
- Food and Drug Administration, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA
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Culp SJ, Beland FA, Heflich RH, Benson RW, Blankenship LR, Webb PJ, Mellick PW, Trotter RW, Shelton SD, Greenlees KJ, Manjanatha MG. Mutagenicity and carcinogenicity in relation to DNA adduct formation in rats fed leucomalachite green. Mutat Res 2002; 506-507:55-63. [PMID: 12351145 DOI: 10.1016/s0027-5107(02)00152-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Leucomalachite green is a persistent and prevalent metabolite of malachite green, a triphenylmethane dye that has been used widely as an antifungal agent in the fish industry. Concern over the use of malachite green is due to the potential for consumer exposure, evidence suggestive of tumor promotion in rodent liver, and suspicion of carcinogenicity based on structure-activity relationships. Our previous study indicated that feeding rodents malachite or leucomalachite green resulted in a dose-related increase in liver DNA adducts, and that, in general, exposure to leucomalachite green caused an increase in the number and severity of changes greater than was observed following exposure to malachite green. To characterize better the genotoxicity of leucomalachite green, female Big Blue rats were fed leucomalachite green at doses of 0, 9, 27, 91, 272, or 543 ppm for up to 32 weeks. The livers were analyzed for lacI mutations at 4, 16, and 32 weeks and DNA adducts at 4 weeks. Using a 32P-postlabeling assay, we observed a dose-related DNA adduct in the livers of rats fed 91, 272, and 543 ppm leucomalachite green. A approximately 3-fold increase in lacI mutant frequency was found in the livers of rats fed 543 ppm leucomalachite green for 16 weeks, but significant increases in mutant frequencies were not found for any of the other doses or time points assayed. We also conducted 2-year tumorigenesis bioassays in female and male F344 rats using 0, 91, 272, and 543 ppm leucomalachite green. Preliminary results indicate an increasing dose trend in lung adenomas in male rats treated with leucomalachite green, but no increase in the incidence of liver tumors in either sex of rat. These results suggest that the DNA adduct formed in the livers of rats fed leucomalachite green has little mutagenic or carcinogenic consequence.
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Affiliation(s)
- S J Culp
- Food and Drug Administration, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.
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20
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Manjanatha MG, Shelton SD, Culp SJ, Blankenship LR, Casciano DA. DNA adduct formation and molecular analysis of in vivo lacI mutations in the mammary tissue of Big Blue rats treated with 7, 12-dimethylbenz[a]anthracene. Carcinogenesis 2000; 21:265-73. [PMID: 10657967 DOI: 10.1093/carcin/21.2.265] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recently we compared the lacI and Hprt mutant frequencies (MFs) and types of mutations in lymphocytes of Big Blue((R)) (BB) rats exposed to 7,12-dimethylbenz[a]anthracene (DMBA) under conditions that result in mammary gland tumors. In this study, we have examined the target mammary tissue for DMBA-induced DNA adducts, lacI MF and types of lacI mutations. Seven-week-old female BB rats were given single doses of 0, 20 or 130 mg/kg DMBA by gavage and the DNA adducts and lacI MFs in the mammary tissue were measured over a period of 14 days and 18 weeks, respectively, following treatment. The lacI MF in the mammary tissue increased for 10 weeks and then remained relatively constant; 130 mg/kg DMBA produced a 14-fold increase in the MF (255 +/- 50 x 10(-6) p.f.u.) over control MF (18. 3 +/- 4 x 10(-6) p.f.u.). (32)P-post-labeling analysis of DNA from mammary tissue and splenic lymphocytes of treated rats revealed two major adducts. Comparison of these adducts with DMBA standards indicated that the adducts formed by DMBA involved both G:C and A:T base pairs. DNA sequencing revealed that the majority of DMBA-induced lacI mutations were base pair substitutions and that A:T-->T:A (44% of the independent mutations) and G:C-->T:A (24% of the independent mutations) transversions were the predominant types. Furthermore, the mutational results revealed a 'hotspot' for a G-->T mutation in codon 95 (GTG-->TTG) of the lacI gene in mammary tissue. These results suggest that DMBA is highly mutagenic to lacI in mammary tissue and that adducts with both G:C and A:T base pairs participate in forming mutations in DMBA-treated BB rats.
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Affiliation(s)
- M G Manjanatha
- Department of Health and Human Services, Food and Drug Administration, National Center for Toxicological Research, Divisions of Genetic and Biochemical Toxicology, Jefferson, AR 72079, USA.
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Culp SJ, Blankenship LR, Kusewitt DF, Doerge DR, Mulligan LT, Beland FA. Toxicity and metabolism of malachite green and leucomalachite green during short-term feeding to Fischer 344 rats and B6C3F1 mice. Chem Biol Interact 1999; 122:153-70. [PMID: 10682936 DOI: 10.1016/s0009-2797(99)00119-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Malachite green, an N-methylated diaminotriphenylmethane dye, has been widely used as an antifungal agent in commercial fish hatcheries. Malachite green is reduced to and persists as leucomalachite green in the tissues of fish. Female and male B6C3F1 mice and Fischer 344 rats were fed up to 1200 ppm malachite green or 1160 ppm leucomalachite green for 28 days to determine the toxicity and metabolism of the dyes. Apoptosis in the transitional epithelium of the urinary bladder occurred in all mice fed the highest dose of leucomalachite green. This was not observed with malachite green. Hepatocyte vacuolization was present in rats administered malachite green or leucomalachite green. Rats given leucomalachite green also had apoptotic thyroid follicular epithelial cells. Decreased T4 and increased TSH levels were observed in male rats given leucomalachite green. A comparison of adverse effects suggests that exposure of rats or mice to leucomalachite green causes a greater number of and more severe changes than exposure to malachite green. N-Demethylated and N-oxidized malachite green and leucomalachite green metabolites, including primary arylamines, were detected by high performance liquid chromatography/mass spectrometry in the livers of treated rats. 32P-Postlabeling analyses indicated a single adduct or co-eluting adducts in the liver DNA. These data suggest that malachite green and leucomalachite green are metabolized to primary and secondary arylamines in the tissues of rodents and that these derivatives, following subsequent activation, may be responsible for the adverse effects associated with exposure to malachite green.
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Affiliation(s)
- S J Culp
- National Center for Toxicological Research, Jefferson, AR 72079, USA.
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