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Thompson JC, Dao WT, Ku A, Rodriguez-Beltran SL, Amezcua M, Palomino AY, Lien T, Salzameda NT. Synthesis and activity of isoleucine sulfonamide derivatives as novel botulinum neurotoxin serotype A light chain inhibitors. Bioorg Med Chem 2020; 28:115659. [PMID: 32828426 DOI: 10.1016/j.bmc.2020.115659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 11/20/2022]
Abstract
The botulinum neurotoxin (BoNT) is the most lethal protein known to man causing the deadly disease botulinum. The neurotoxin, composed of a heavy (HC) and light (LC) chain, work in concert to cause muscle paralysis. A therapeutic strategy to treat individuals infected with the neurotoxin is inhibiting the catalytic activity of the BoNT LC. We report the synthesis, inhibition study and computational docking analysis of novel small molecule BoNT/A LC inhibitors. A structure activity relationship study resulted in the discovery of d-isoleucine functionalized with a hydroxamic acid on the C-terminal and a biphenyl with chlorine at C- 2 connected by a sulfonamide linker at the N-terminus. This compound has a measured IC50 of 0.587 µM for the BoNT/A LC. Computational docking analysis indicates the sulfonamide linker adopts a geometry that is advantageous for binding to the BoNT LC active site. In addition, Arg363 is predicted to be involved in key binding interactions with the scaffold in this study.
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Affiliation(s)
- Jordan C Thompson
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Wendy T Dao
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Alex Ku
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Sandra L Rodriguez-Beltran
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Martin Amezcua
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Alejandra Y Palomino
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Thanh Lien
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA
| | - Nicholas T Salzameda
- Department of Chemistry & Biochemistry, California State University, 800 N. State College, Fullerton, CA, 92834, USA.
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Ferrari A, Manca M, Tugnoli V, Alberto L. Pharmacological differences and clinical implications of various botulinum toxin preparations: a critical appraisal. FUNCTIONAL NEUROLOGY 2019; 33:7-18. [PMID: 29633692 DOI: 10.11138/fneur/2018.33.1.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Three different type A botulinum neurotoxins (BoNTAs) - onabotulinumtoxinA, abobotulinumtoxinA and incobotulinumtoxinA) - are currently marketed in Europe to treat several conditions. Differences between BoNTA preparations, which depend on their specific biotypes and manufacturing processes, lead to clinically relevant pharmacotherapeutic dissimilarities. All three available products are separately recognized and reviewed in American Academy of Neurology guidelines. The neurotoxin load/100U is likewise different among the different BoNTAs, with the result that the specific potency of the 150kD BoNTA neurotoxin is calculated as 137 units/ng for onabotulinumtoxinA, 154 units/ng for abobotulinumtoxinA, and 227 units/ng for incobotulinumtoxinA. It is important for clinicians to have all three BoNTAs available in order to choose the most suitable preparation for the specific indication in the single patient. Commercially available BoNTAs must be recognized as different from one another, and therefore as non-interchangeable. The essential experience of the clinician is of the utmost importance in choosing the most appropriate treatment.
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3
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Kim NY, Ahn HB, Yu CH, Song DH, Hur GH, Shin YK, Shin S. Intradermal immunization with botulinum neurotoxin serotype E DNA vaccine induces humoral and cellular immunity and protects against lethal toxin challenge. Hum Vaccin Immunother 2018; 15:412-419. [PMID: 30235058 DOI: 10.1080/21645515.2018.1526554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by the spore-forming, gram-positive, anaerobic bacterium Clostridium botulinum are the most toxic substances known and cause botulism, flaccid paralysis, or death. Owing to their high lethality, BoNTs are classified as category A agents by the Centers for Disease Control (CDC). Currently, there are no vaccines available to protect against BoNTs, so the rapid development of a safe and effective vaccine is important. DNA-based vaccines have recently drawn great attention because they can be developed quickly and can be applied in mass vaccination strategies to prevent disease outbreaks. Here, we report on the immunogenic and protective efficacy of a DNA vaccine, encoding a 50-kDa carboxy-terminal fragment of the BoNT serotype E heavy chain, which is delivered via an intradermal route. This plasmid DNA vaccine induced robust humoral and cellular BoNT/E-specific immune responses and completely protected animals against lethal challenge with BoNT/E. These results not only indicate that DNA vaccines could be further developed as safe and effective candidates for vaccines against BoNTs but also suggest a possible approach for developing vaccines that protect against bio-threat toxins.
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Affiliation(s)
| | - Hye Bin Ahn
- b Graduate School of Convergence Science and Technology , Seoul National University , Seoul , Republic of Korea
| | - Chi Ho Yu
- c Agency for Defense Development , Daejon , Republic of Korea
| | - Dong Hyun Song
- c Agency for Defense Development , Daejon , Republic of Korea
| | | | - Young Kee Shin
- d College of Pharmacy , Seoul National University , Seoul , Republic of Korea
| | - Sungho Shin
- e Bio-MAX/N-Bio , Seoul National University , Seoul , Republic of Korea
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An FL, Sun DM, Wang RZ, Yang MH, Luo J, Kong LY. Trijugin- and mexicanolide-type limonoids from the fruits of Heynea trijuga that reverse multidrug resistance in MCF-7/DOX cells. PHYTOCHEMISTRY 2018; 151:42-49. [PMID: 29665475 DOI: 10.1016/j.phytochem.2018.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 03/30/2018] [Accepted: 04/09/2018] [Indexed: 06/08/2023]
Abstract
Eleven previously undescribed limonoids, trichisins A-K, including eight structural analogues A-H of trijugin and three H-J mexicanolide derivatives, together with two known mexicanolide derivatives were isolated from the fruits of Heynea trijuga Roxb. ex Sims. The structure determination was based on extensive physical data analyses (NMR, MS), and their basic skeletons and the absolute configurations of trichisins A, B, E, K and trichiconnarone A were assigned via X-ray crystallographic analysis (Cu Kα radiation). The hemiketal motifs in trijugins A, B, and E-G are rare in limonoids. Bioactivity screenings suggested that the trijugin H and mexicanolide-type trichiconnarones A and B limonoids were effective in reversing resistance in MCF-7/DOX cells at a nontoxic concentration of 50 μM with IC50 values of 12.45, 10.86, and 14.96 μM, respectively.
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Affiliation(s)
- Fa-Liang An
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China; State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, People's Republic of China
| | - Dong-Mei Sun
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China
| | - Rui-Zhi Wang
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China
| | - Ming-Hua Yang
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China
| | - Jun Luo
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
| | - Ling-Yi Kong
- State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
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The Effect of Albumin and Platelet-Poor Plasma Supplemented Botulinum A Toxin on Bioavaliability. Ann Plast Surg 2017; 78:436-442. [DOI: 10.1097/sap.0000000000000957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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6
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Monoclonal Antibodies Targeting the Alpha-Exosite of Botulinum Neurotoxin Serotype/A Inhibit Catalytic Activity. PLoS One 2015; 10:e0135306. [PMID: 26275214 PMCID: PMC4537209 DOI: 10.1371/journal.pone.0135306] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 07/20/2015] [Indexed: 12/12/2022] Open
Abstract
The paralytic disease botulism is caused by botulinum neurotoxins (BoNT), multi-domain proteins containing a zinc endopeptidase that cleaves the cognate SNARE protein, thereby blocking acetylcholine neurotransmitter release. Antitoxins currently used to treat botulism neutralize circulating BoNT but cannot enter, bind to or neutralize BoNT that has already entered the neuron. The light chain endopeptidase domain (LC) of BoNT serotype A (BoNT/A) was targeted for generation of monoclonal antibodies (mAbs) that could reverse paralysis resulting from intoxication by BoNT/A. Single-chain variable fragment (scFv) libraries from immunized humans and mice were displayed on the surface of yeast, and 19 BoNT/A LC-specific mAbs were isolated by using fluorescence-activated cell sorting (FACS). Affinities of the mAbs for BoNT/A LC ranged from a KD value of 9.0×10−11 M to 3.53×10−8 M (mean KD 5.38×10−9 M and median KD 1.53×10−9 M), as determined by flow cytometry analysis. Eleven mAbs inhibited BoNT/A LC catalytic activity with IC50 values ranging from 8.3 ~73×10−9 M. The fine epitopes of selected mAbs were also mapped by alanine-scanning mutagenesis, revealing that the inhibitory mAbs bound the α-exosite region remote from the BoNT/A LC catalytic center. The results provide mAbs that could prove useful for intracellular reversal of paralysis post-intoxication and further define epitopes that could be targeted by small molecule inhibitors.
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Xue S, Javor S, Hixon MS, Janda KD. Probing BoNT/A protease exosites: implications for inhibitor design and light chain longevity. Biochemistry 2014; 53:6820-4. [PMID: 25295706 PMCID: PMC4222541 DOI: 10.1021/bi500950x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
![]()
Botulinum
neurotoxin serotype A (BoNT/A) is one of the most lethal
toxins known. Its extreme toxicity is due to its light chain (LC),
a zinc protease that cleaves SNAP-25, a synaptosome-associated protein,
leading to the inhibition of neuronal activity. Studies on BoNT/A
LC have revealed that two regions, termed exosites, can play an important
role in BoNT catalytic activity. A clear understanding of how these
exosites influence neurotoxin catalytic activity would provide a critical
framework for deciphering the mechanism of SNAP-25 cleavage and the
design of inhibitors. Herein, based on the crystallographic structure
of BoNT/A LC complexed with its substrate, we designed an α-exosite
binding probe. Experiments with this unique probe demonstrated that
α-exosite binding enhanced both catalytic activity and stability
of the LC. These data help delineate why α-exosite binding is
needed for SNAP-25 cleavage and also provide new insights into the
extended lifetime observed for BoNT/A LC in vivo.
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Affiliation(s)
- Song Xue
- Departments of Chemistry and Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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8
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Mizanur RM, Stafford RG, Ahmed SA. Cleavage of SNAP25 and its shorter versions by the protease domain of serotype A botulinum neurotoxin. PLoS One 2014; 9:e95188. [PMID: 24769566 PMCID: PMC4000213 DOI: 10.1371/journal.pone.0095188] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/25/2014] [Indexed: 11/18/2022] Open
Abstract
Various substrates, catalysts, and assay methods are currently used to screen inhibitors for their effect on the proteolytic activity of botulinum neurotoxin. As a result, significant variation exists in the reported results. Recently, we found that one source of variation was the use of various catalysts, and have therefore evaluated its three forms. In this paper, we characterize three substrates under near uniform reaction conditions using the most active catalytic form of the toxin. Bovine serum albumin at varying optimum concentrations stimulated enzymatic activity with all three substrates. Sodium chloride had a stimulating effect on the full length synaptosomal-associated protein of 25 kDa (SNAP25) and its 66-mer substrates but had an inhibitory effect on the 17-mer substrate. We found that under optimum conditions, full length SNAP25 was a better substrate than its shorter 66-mer or 17-mer forms both in terms of kcat, Km, and catalytic efficiency kcat/Km. Assay times greater than 15 min introduced large variations and significantly reduced the catalytic efficiency. In addition to characterizing the three substrates, our results identify potential sources of variations in previous published results, and underscore the importance of using well-defined reaction components and assay conditions.
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Affiliation(s)
- Rahman M. Mizanur
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Robert G. Stafford
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - S. Ashraf Ahmed
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
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Caglič D, Krutein MC, Bompiani KM, Barlow DJ, Benoni G, Pelletier JC, Reitz AB, Lairson LL, Houseknecht KL, Smith GR, Dickerson TJ. Identification of clinically viable quinolinol inhibitors of botulinum neurotoxin A light chain. J Med Chem 2014; 57:669-76. [PMID: 24387280 PMCID: PMC3983388 DOI: 10.1021/jm4012164] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Botulinum neurotoxins (BoNT) are the most potent toxins known and a significant bioterrorist threat. Few small molecule compounds have been identified that are active in cell-based or animal models, potentially due to toxin enzyme plasticity. Here we screened commercially available quinolinols, as well as synthesized hydroxyquinolines. Seventy-two compounds had IC50 values below 10 μM, with the best compound exhibiting submicromolar inhibition (IC50 = 0.8 μM). Structure-activity relationship trends showed that the enzyme tolerates various substitutions at R1 but has a clear preference for bulky aryl amide groups at R2, while methylation at R3 increased inhibitor potency. Evaluation of the most potent compounds in an ADME panel showed that these compounds possess poor solubility at pH 6.8, but display excellent solubility at low pH, suggesting that oral dosing may be possible. Our data show the potential of quinolinol compounds as BoNT therapeutics due to their good in vitro potencies and favorable ADME properties.
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Affiliation(s)
- Dejan Caglič
- Department of Chemistry, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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10
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Burtea A, Salzameda NT. Discovery and SAR study of a sulfonamide hydroxamic acid inhibitor for the botulinum neurotoxin serotype A light chain. MEDCHEMCOMM 2014. [DOI: 10.1039/c4md00053f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Through the use of chemical synthesis and high throughput screening, we discovered a sulfonamide hydroxamic acid inhibitor for the botulinum neurotoxin serotype A light chain. A structure activity relationship study of the parent inhibitor resulted in the synthesis of a new inhibitor with an IC50of 0.95 ± 0.60 μM for the BoNT/A LC.
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Affiliation(s)
- Alexander Burtea
- Department of Chemistry & Biochemistry
- California State University
- Fullerton, USA
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11
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Húngaro HM, Alvarenga VO, Peña WEL, Sant'Ana ADS. Hearts of palms preserves and botulism in Brazil: An overview of outbreaks, causes and risk management strategies. Trends Food Sci Technol 2013. [DOI: 10.1016/j.tifs.2013.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Cezairliyan B, Vinayavekhin N, Grenfell-Lee D, Yuen GJ, Saghatelian A, Ausubel FM. Identification of Pseudomonas aeruginosa phenazines that kill Caenorhabditis elegans. PLoS Pathog 2013; 9:e1003101. [PMID: 23300454 PMCID: PMC3536714 DOI: 10.1371/journal.ppat.1003101] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 11/09/2012] [Indexed: 02/05/2023] Open
Abstract
Pathogenic microbes employ a variety of methods to overcome host defenses, including the production and dispersal of molecules that are toxic to their hosts. Pseudomonas aeruginosa, a Gram-negative bacterium, is a pathogen of a diverse variety of hosts including mammals and the nematode Caenorhabditis elegans. In this study, we identify three small molecules in the phenazine class that are produced by P. aeruginosa strain PA14 that are toxic to C. elegans. We demonstrate that 1-hydroxyphenazine, phenazine-1-carboxylic acid, and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of phenazine-1-carboxylic acid and pyocyanin are pH-dependent at non-overlapping pH ranges. We found that acidification of the growth medium by PA14 activates the toxicity of phenazine-1-carboxylic acid, which is the primary toxic agent towards C. elegans in our assay. Pyocyanin is not toxic under acidic conditions and 1-hydroxyphenazine is produced at concentrations too low to kill C. elegans. These results suggest a role for phenazine-1-carboxylic acid in mammalian pathogenesis because PA14 mutants deficient in phenazine production have been shown to be defective in pathogenesis in mice. More generally, these data demonstrate how diversity within a class of metabolites could affect bacterial toxicity in different environmental niches.
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Affiliation(s)
- Brent Cezairliyan
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Nawaporn Vinayavekhin
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Daniel Grenfell-Lee
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Grace J. Yuen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Program in Immunology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alan Saghatelian
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (AS); (FMA)
| | - Frederick M. Ausubel
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- * E-mail: (AS); (FMA)
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Eichhorn T, Dolimbek BZ, Deeg K, Efferth T, Atassi MZ. Inhibition in vivo of the activity of botulinum neurotoxin A by small molecules selected by virtual screening. Toxicon 2012; 60:1180-90. [PMID: 22960451 DOI: 10.1016/j.toxicon.2012.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 10/28/2022]
Abstract
To search for small molecular size inhibitors of botulinum neurotoxin A (BoNT/A) endopeptidase activity, we have screened the NCI library containing about 1 million structures against the substrate binding pocket of BoNT/A. Virtual screening (VS) was performed with the software Glide (Grid-based ligand docking energetics) and the findings were confirmed by AutoDock. Ten compounds were found that had favorable energetic and glide criteria and 5 of these compounds were selected for their ability to protect mice in vivo against a lethal dose of BoNT/A. Each compound was incubated at different molar excesses with a lethal dose of the toxin and then the mixture injected intravenously into mice. At 4690 M excess, compounds NSC94520 and NSC99639 protected all (100%) the mice from lethal toxicity. Compounds NSC48461 and NSC627733 gave 75% protection. Compound NSC348884 showed the least inhibition of toxicity allowing only a fraction (25%) of the mice to survive challenge with a lethal dose; and in the case of the mice that did not survive there was a considerable delay of mortality. At 2400 M excess compounds NSC94520 remained fully protective while and NSC99639 afforded 75% protection and at 1200 M excess each of these two compounds gave 50% protection. The two compounds gave no protection at 600 or less molar excess. When each compound was administered intravenously at 4690 M excess at different times (from 1 h to 6 h) after the intravenous injection of the active toxin, none of the compounds was able to protect the animals from toxicity. The findings show the value of VS in identifying potential inhibitors of the toxin for further development and improvement.
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Affiliation(s)
- Tolga Eichhorn
- Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany
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Caglič D, Dickerson TJ. A coincidence detector triggers botulinum neurotoxin translocation. Future Microbiol 2012; 7:185-8. [PMID: 22324987 DOI: 10.2217/fmb.11.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the deadliest poisons known to man. They possess a particular duality, rapidly increasing clinical utility for a wide range of disorders and large concern as a possible weapon of bioterrorism. While great strides have been made in the structural and biochemical understanding of the mechanism of intoxication, the specific molecular details behind BoNT translocation out of endosomes remain elusive. In this study, it was conclusively demonstrated that light chain metalloprotease translocation can only occur in the presence of low pH, as is found in endosomes, and GT1b ganglioside coreceptor, whose role was previously thought to only be in cell surface recognition by the toxin. As stated by the authors, the BoNT receptor-binding domain therefore serves as a 'coincidence receptor' in that pH sensing and conformational change to a translocation competent form must be coupled in some way to receptor binding. Further study using atomic force microscopy also suggested the presence of oligomeric toxin channels that can be inhibited by the natural product toosendanin. This data revises the model of BoNT intoxication and demonstrates a mechanism for the amazing temporal and spatial control possessed by this toxin, which ultimately manifests in its extreme potency.
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Affiliation(s)
- Dejan Caglič
- Department of Chemistry & Worm Institute of Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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15
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Zakhari JS, Kinoyama I, Hixon MS, Di Mola A, Globisch D, Janda KD. Formulating a new basis for the treatment against botulinum neurotoxin intoxication: 3,4-Diaminopyridine prodrug design and characterization. Bioorg Med Chem 2011; 19:6203-9. [PMID: 21975066 DOI: 10.1016/j.bmc.2011.09.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
Abstract
Botulism is a disease characterized by neuromuscular paralysis and is produced from botulinum neurotoxins (BoNTs) found within the Gram positive bacterium Clostridium botulinum. This bacteria produces the most deadliest toxin known, with lethal doses as low as 1 ng/kg. Due to the relative ease of production and transport, the use of these agents as potential bioterrorist weapons has become of utmost concern. No small molecule therapies against BoNT intoxication have been approved to date. However, 3,4-diaminopyridine (3,4-DAP), a potent reversible inhibitor of voltage-gated potassium channels, is an effective cholinergic agonist used in the treatment of neuromuscular degenerative disorders that require cholinergic enhancement. 3,4-DAP has also been shown to facilitate recovery of neuromuscular action potential post botulinum intoxication by blocking K(+) channels. Unfortunately, 3,4-DAP displays toxicity largely due to blood-brain-barrier (BBB) penetration. As a dual-action prodrug approach to cholinergic enhancement we have designed carbamate and amide conjugates of 3,4-DAP. The carbamate prodrug is intended to be a slowly reversible inhibitor of acetylcholinesterase (AChE) along the lines of the stigmines thereby allowing increased persistence of released acetylcholine within the synaptic cleft. As a secondary activity, cleavage of the carbamate prodrug by AChE will afford the localized release of 3,4-DAP, which in turn, will enhance the pre-synaptic release of additional acetylcholine. Being a competitive inhibitor with respect to acetylcholine, the activity of the prodrug will be greatest at the synaptic junctions most depleted of acetylcholine. Here we report upon the synthesis and biochemical characterization of three new classes of prodrugs intended to limit previously reported stability and toxicity issues. Of the prodrugs examined, compound 32, demonstrated the most clinically relevant half-life of 2.76 h, while selectively inhibiting AChE over butyrylcholinesterase--a plasma-based high activity esterase. Future in vivo studies could provide validation of prodrug 32 as a potential treatment against BoNT intoxication as well as other neuromuscular disorders.
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Affiliation(s)
- Joseph S Zakhari
- Department of Chemistry, Immunology and Microbial Sciences, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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16
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Al-Saleem FH, Nasser Z, Olson RM, Cao L, Simpson LL. Identification of the factors that govern the ability of therapeutic antibodies to provide postchallenge protection against botulinum toxin: a model for assessing postchallenge efficacy of medical countermeasures against agents of bioterrorism and biological warfare. J Pharmacol Exp Ther 2011; 338:503-17. [PMID: 21586604 PMCID: PMC3141897 DOI: 10.1124/jpet.111.180653] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 05/16/2011] [Indexed: 11/22/2022] Open
Abstract
Therapeutic antibodies are one of the major classes of medical countermeasures that can provide protection against potential bioweapons such as botulinum toxin. Although a broad array of antibodies are being evaluated for their ability to neutralize the toxin, there is little information that defines the circumstances under which these antibodies can be used. In the present study, an effort was made to quantify the temporal factors that govern therapeutic antibody use in a postchallenge scenario. Experiments were done involving inhalation administration of toxin to mice, intravenous administration to mice, and direct application to murine phrenic nerve-hemidiaphragm preparations. As part of this study, several pharmacokinetic characteristics of botulinum toxin and neutralizing antibodies were measured. The core observation that emerged from the work was that the window of opportunity within which postchallenge administration of antibodies exerted a beneficial effect increased as the challenge dose of toxin decreased. The critical factor in establishing the window of opportunity was the amount of time needed for fractional redistribution of a neuroparalytic quantum of toxin from the extraneuronal space to the intraneuronal space. This redistribution event was a dose-dependent phenomenon. It is likely that the approach used to identify the factors that govern postchallenge efficacy of antibodies against botulinum toxin can be used to assess the factors that govern postchallenge efficacy of medical countermeasures against any agent of bioterrorism or biological warfare.
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Affiliation(s)
- Fetweh H Al-Saleem
- Department of Medicine, Jefferson Medical College, 1020 Locust Street, Philadelphia, PA 119107, USA
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17
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Čapek P, Zhang Y, Barlow DJ, Houseknecht KL, Smith GR, Dickerson TJ. Enhancing the Pharmacokinetic Properties of Botulinum Neurotoxin Serotype A Protease Inhibitors Through Rational Design. ACS Chem Neurosci 2011; 2:288-293. [PMID: 21743830 DOI: 10.1021/cn200021q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Botulinum neurotoxin (BoNT), the etiological agent that causes the neuroparalytic disease botulism, has become a highly studied drug target in light of the potential abuse of this toxin as a weapon of bioterrorism. In particular, small molecule inhibitors of the light chain metalloprotease of BoNT serotype A have received significant attention and a number of small molecule and biologic inhibitors have been reported. However, all small molecules reported have been identified from either primary screens or medicinal chemistry follow-up studies, and the pharmacokinetic profiles of these compounds have not been addressed. In this study, we have removed the pharmacologic liabilities of one of the best compounds reported to date, 2,4-dichlorocinnamate hydroxamic acid, and in the process, uncovered a related class of benzothiophene hydroxamic acids that are significantly more potent inhibitors of the BoNT/A light chain, while also possessing greatly improved ADME properties, with the best compound showing the most potent inhibition of BoNT/A light chain reported (K(i) = 77 nM). Using a strategy of incorporating traditional drug development filters early into the discovery process, potential liabilities in BoNT/A lead compounds have been illuminated and removed, clearing the path for advancement into further pharmacologic optimization and in vivo efficacy testing.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry and Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yan Zhang
- Fox Chase Chemical Diversity Center, Doylestown, Pennsylvania, United States
| | - Deborah J. Barlow
- Department of Pharmaceutical Sciences, University of New England College of Pharmacy, Portland, Maine, United States
| | - Karen L. Houseknecht
- Department of Pharmaceutical Sciences, University of New England College of Pharmacy, Portland, Maine, United States
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, Doylestown, Pennsylvania, United States
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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18
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Mayorov AV, Willis B, Di Mola A, Adler D, Borgia J, Jackson O, Wang J, Luo Y, Tang L, Knapp RJ, Natarajan C, Goodnough MC, Zilberberg N, Simpson LL, Janda KD. Symptomatic relief of botulinum neurotoxin/a intoxication with aminopyridines: a new twist on an old molecule. ACS Chem Biol 2010; 5:1183-91. [PMID: 20936877 DOI: 10.1021/cb1002366] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Botulinum neurotoxins (BoNT) are the etiological agents responsible for botulism, a disease characterized by peripheral neuromuscular blockade and a characteristic flaccid paralysis of humans. BoNT/A is the most toxic protein known to man and has been classified by the Centers of Disease Control (CDC) as one of the six highest-risk threat agents for bioterrorism. Of particular concern is the apparent lack of clinical interventions that can reverse cellular intoxication. Efforts to uncover molecules that can act within an intoxicated cell so as to provide symptomatic relief to BoNT/A are paramount. Aminopyridines have shown clinical efficacy for multiple sclerosis treatment as well as BoNT/A intoxication; yet, aminopyridines for BoNT/A treatment has been abandoned because of blood brain barrier (BBB) penetration producing undesired neurotoxic side effects. Two aminopyridines (5 and 11) exhibited inhibitory activity toward Shaker-IR voltage-gated potassium (K(V)1.x) channels with potencies similar to that of the previous "gold-standard", 3,4-diaminopyridine (3,4-DAP), including reversal of symptoms from BoNT-induced paralysis in phrenic nerve-hemidiaphragm preparations. Importantly, pharmacokinetic experiments revealed a lack of BBB penetration of 5, which is a significant advancement toward resolving the neurotoxicity issues associated with prolonged 3,4-DAP treatments. Finally, 5 was found to be as effective as 3,4-DAP in rescuing BoNT-poisoned mice in the mouse lethality assay, signifying an optimized balance between the undesired permeability across the BBB and the required permeability across lipid cellular membranes. The results demonstrate that 5 is the most promising small molecule K(+) channel inhibitor discovered to date for the treatment of BoNT/A intoxication.
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Affiliation(s)
- Alexander V. Mayorov
- Departments of Chemistry and Immunology, Skaggs Institute for Chemical Biology and Worm Institute of Research & Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Bert Willis
- Departments of Chemistry and Immunology, Skaggs Institute for Chemical Biology and Worm Institute of Research & Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Antonia Di Mola
- Departments of Chemistry and Immunology, Skaggs Institute for Chemical Biology and Worm Institute of Research & Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Derek Adler
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Jennifer Borgia
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Olin Jackson
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Jie Wang
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Yongyi Luo
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Lei Tang
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Richard J. Knapp
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | - Chandra Natarajan
- Sanofi-Aventis, Discovery Metabolism and Pharmacokinetics Safety Department, Bridgewater, New Jersey 08807, United States
| | | | - Noam Zilberberg
- Department of Life Sciences, Ben Gurion University, Beer Sheva 84105, Israel
| | - Lance L. Simpson
- Department of Medicine Jefferson Medical College, Thomas Jefferson University, 1020 Locust St, Rm 314-JAH, Philadelphia, Pennsylvania 19107, United States
| | - Kim D. Janda
- Departments of Chemistry and Immunology, Skaggs Institute for Chemical Biology and Worm Institute of Research & Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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19
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Affiliation(s)
- Mauricio Montal
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California 92093-0366;
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20
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Chang TW, Blank M, Janardhanan P, Singh BR, Mello C, Blind M, Cai S. In vitro selection of RNA aptamers that inhibit the activity of type A botulinum neurotoxin. Biochem Biophys Res Commun 2010; 396:854-60. [PMID: 20452328 DOI: 10.1016/j.bbrc.2010.05.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
Abstract
The category A agent, botulinum neurotoxin (BoNT), is the most toxic molecule known to mankind. The endopeptidase activity of light chain domain of BoNT is the cause for the inhibition of the neurotransmitter release and the flaccid paralysis that leads to lethality in botulism. Currently, antidotes are not available to reverse the flaccid paralysis caused by BoNT. In the present study, we have identified three RNA aptamers through SELEX-process, which bind strongly to the light chain of type A BoNT (BoNT/A) and inhibit the endopeptidase activity, with IC(50) in low nM range. Inhibition kinetic studies reveal low nM K(I) and non-competitive nature of their inhibition. Aptamers are unique group of molecules as therapeutics, and this is first report of their development as an antidote against botulism. These data on K(I) and IC(50) strongly suggest that the aptamers have strong potential as antidotes that can reverse the symptom caused by BoNT/A.
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Affiliation(s)
- Tzuu-Wang Chang
- Department of Chemistry and Biochemistry, and Botulinum Research Center, University of Massachusetts Dartmouth, North Dartmouth, MA 02747, USA
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21
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A single-domain llama antibody potently inhibits the enzymatic activity of botulinum neurotoxin by binding to the non-catalytic alpha-exosite binding region. J Mol Biol 2010; 397:1106-18. [PMID: 20138889 DOI: 10.1016/j.jmb.2010.01.070] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 01/27/2010] [Indexed: 02/07/2023]
Abstract
Ingestion or inhalation of botulinum neurotoxin (BoNT) results in botulism, a severe and frequently fatal disease. Current treatments rely on antitoxins, which, while effective, cannot reverse symptoms once BoNT has entered the neuron. For treatments that can reverse intoxication, interest has focused on developing inhibitors of the enzymatic BoNT light chain (BoNT Lc). Such inhibitors typically mimic substrate and bind in or around the substrate cleavage pocket. To explore the full range of binding sites for serotype A light chain (BoNT/A Lc) inhibitors, we created a library of non-immune llama single-domain VHH (camelid heavy-chain variable region derived from heavy-chain-only antibody) antibodies displayed on the surface of the yeast Saccharomyces cerevisiae. Library selection on BoNT/A Lc yielded 15 yeast-displayed VHH with equilibrium dissociation constants (K(d)) from 230 to 0.03 nM measured by flow cytometry. Eight of 15 VHH inhibited the cleavage of substrate SNAP25 (synaptosome-associated protein of 25,000 Da) by BoNT/A Lc. The most potent VHH (Aa1) had a solution K(d) for BoNT/A Lc of 1.47 x 10(-)(10) M and an IC(50) (50% inhibitory concentration) of 4.7 x 10(-)(10) M and was resistant to heat denaturation and reducing conditions. To understand the mechanism by which Aa1 inhibited catalysis, we solved the X-ray crystal structure of the BoNT/A Lc-Aa1 VHH complex at 2.6 A resolution. The structure reveals that the Aa1 VHH binds in the alpha-exosite of the BoNT/A Lc, far from the active site for catalysis. The study validates the utility of non-immune llama VHH libraries as a source of enzyme inhibitors and identifies the BoNT/A Lc alpha-exosite as a target for inhibitor development.
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22
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Nakai Y, Pellett S, Tepp WH, Johnson EA, Janda KD. Toosendanin: synthesis of the AB-ring and investigations of its anti-botulinum properties (Part II). Bioorg Med Chem 2009; 18:1280-7. [PMID: 20044261 DOI: 10.1016/j.bmc.2009.12.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/04/2009] [Accepted: 12/08/2009] [Indexed: 10/20/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the etiological agents responsible for botulism, a disease characterized by peripheral neuromuscular blockade and a characteristic flaccid paralysis of humans. The natural product toosendanin, a limonoid, is a traditional Chinese medicine that has reported anti-botulinum properties in animal models. Toosendanin effectively inhibits the biological activity of BoNT/A in neuronal cells at concentrations of 200 nM, and partial inhibition can be observed with concentrations as low as 8 nM. Mechanistically, toosendanin's inhibition is due to prevention of transduction of the BoNT LC through the HC channel. Intriguing questions as to the molecular architecture of toosendanin as related to its anti-botulinum properties have focused our attention on a synthesis of toosendanin's unusual AB-ring, containing a unique bridged hemi-acetal. Within the current work, a synthetic strategy allowing access to the AB-fragment of toosendanin was achieved from a trans-decalin system. In addition, this fragment was examined for its modulation of BoNT/A intoxication in a rat spinal cord cellular assay.
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Affiliation(s)
- Yuya Nakai
- Departments of Chemistry and Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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23
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Cai S, Lindo P, Park JB, Vasa K, Singh BR. The identification and biochemical characterization of drug-like compounds that inhibit botulinum neurotoxin serotype A endopeptidase activity. Toxicon 2009; 55:818-26. [PMID: 20003913 DOI: 10.1016/j.toxicon.2009.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 10/17/2009] [Accepted: 11/17/2009] [Indexed: 10/20/2022]
Abstract
A robust, high-throughput, two-tiered assay for screening small molecule inhibitors against botulinum neurotoxin serotype A was developed and employed to screen 16,544 compounds. Thirty-four compounds were identified as potent hits employing the first-tier assay. Subsequently, nine were confirmed as actives by our second-tier confirmatory assay. Of these, one displayed potent inhibitory efficacy, possessing an IC(50)=16 microM (+/-1.6 microM) in our in vitro assay. This inhibitor (0831-1035) is highly water-soluble, and possesses an IC(50)=47 microM (+/-7.0 microM) in our primary cell culture assay (with virtually no cytotoxicity up to 500 microM), suggesting that this inhibitor is a good candidate for further development as a therapeutic countermeasure to treat botulism resulting from botulinum neurotoxin serotype A intoxication. An enzyme kinetics study indicated that this inhibitor exhibits mixed non-competitive inhibition, with a K(I)=9 microM.
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Affiliation(s)
- Shuowei Cai
- Botulinum Research Center, and Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
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24
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Capková K, Salzameda NT, Janda KD. Investigations into small molecule non-peptidic inhibitors of the botulinum neurotoxins. Toxicon 2009; 54:575-82. [PMID: 19327377 DOI: 10.1016/j.toxicon.2009.03.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 03/03/2009] [Accepted: 03/03/2009] [Indexed: 11/18/2022]
Abstract
Botulinum neurotoxins (BoNTs), proteins secreted by the bacteria genus Clostridium, represent a group of extremely lethal toxins and a potential bioterrorism threat. As the current therapeutic options are of a predominantly prophylactic nature and cannot be used en masse, new strategies and ultimately potential treatments are desperately needed to combat any widespread release of these neurotoxins. In these regards, our laboratory has been working on developing new alternatives to treat botulinum intoxication through the development of inhibitors of the light chain proteases, the etiological agent which causes BoNT intoxication. Such a strategy has required the construction of two high-throughput screens and small molecule non-peptidic libraries; excitingly, inhibitors of the BoNT/A protease have been uncovered and are being optimized via structure activity relationship studies.
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Affiliation(s)
- Katerina Capková
- Departments of Chemistry and Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
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25
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Wipf P, Wang C, Widom J, Petronijevic F, C. Burnett J, E. Nuss J, Bavari S, Gussio R. Synthesis and Biological Evaluation of Inhibitors of Botulinum Neurotoxin Metalloprotease. HETEROCYCLES 2009. [DOI: 10.3987/com-08-s(d)8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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26
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Nakai Y, Tepp WH, Dickerson TJ, Johnson EA, Janda KD. Function-oriented synthesis applied to the anti-botulinum natural product toosendanin. Bioorg Med Chem 2008; 17:1152-7. [PMID: 19131252 DOI: 10.1016/j.bmc.2008.12.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 12/10/2008] [Accepted: 12/14/2008] [Indexed: 10/21/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the etiological agents responsible for botulism, a disease characterized by peripheral neuromuscular blockade and a characteristic flaccid paralysis of humans. The natural product toosendanin is a traditional Chinese medicine which has been reported to have anti-botulinum properties in animal models. To establish what chemical functionalities are necessary for the anti-botulinum properties found within toosendanin, a study was initiated with the goal of using function-oriented synthesis (FOS) as a strategy to begin to unravel toosendanin's powerful anti-botulinum properties. From these studies a new synthetic strategy is put forth allowing access to a 4-acetoxy CD fragment analogue (14) of toosendanin, which was achieved from mesityl oxide and acetylacetone in 14 steps. Animal studies on this fragment are also reported.
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Affiliation(s)
- Yuya Nakai
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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27
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Capková K, Hixon MS, McAllister LA, Janda KD. Toward the discovery of potent inhibitors of botulinum neurotoxin A: development of a robust LC MS based assay operational from low to subnanomolar enzyme concentrations. Chem Commun (Camb) 2008:3525-7. [PMID: 18654701 DOI: 10.1039/b808305c] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of a sensitive, yet reliable assay for the analysis of botulinum neurotoxin A (BoNT/A) inhibitors is described; using this assay a new protease inhibitor was characterized and found to be one of the most potent inhibitors reported to date.
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Affiliation(s)
- Katerina Capková
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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28
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Capková K, Yoneda Y, Dickerson TJ, Janda KD. Synthesis and structure-activity relationships of second-generation hydroxamate botulinum neurotoxin A protease inhibitors. Bioorg Med Chem Lett 2007; 17:6463-6. [PMID: 17951059 DOI: 10.1016/j.bmcl.2007.09.103] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2007] [Revised: 09/27/2007] [Accepted: 09/28/2007] [Indexed: 11/29/2022]
Abstract
Botulinum neurotoxins are the most toxic proteins currently known. Based on a recently identified potent lead structure, 2,4-dichlorocinnamic acid hydroxamate, herein we report on the structure-activity relationship of a series of hydroxamate BoNT/A inhibitors. Among them, 2-bromo-4-chlorocinnamic acid hydroxamate, 2-methyl-4-chlorocinnamic acid hydroxamate, and 2-trifluoromethyl-4-chlorocinnamic acid hydroxamate displayed comparable inhibitory activity to that of the lead structure.
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Affiliation(s)
- Katerina Capková
- Department of Chemistry, and The Skaggs Institute for Chemical Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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29
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Tang J, Park JG, Millard CB, Schmidt JJ, Pang YP. Computer-aided lead optimization: improved small-molecule inhibitor of the zinc endopeptidase of botulinum neurotoxin serotype A. PLoS One 2007; 2:e761. [PMID: 17712409 PMCID: PMC1942119 DOI: 10.1371/journal.pone.0000761] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 07/16/2007] [Indexed: 11/23/2022] Open
Abstract
Optimization of a serotype-selective, small-molecule inhibitor of botulinum neurotoxin serotype A (BoNTA) endopeptidase is a formidable challenge because the enzyme-substrate interface is unusually large and the endopeptidase itself is a large, zinc-binding protein with a complex fold that is difficult to simulate computationally. We conducted multiple molecular dynamics simulations of the endopeptidase in complex with a previously described inhibitor (Kiapp of 7±2.4 µM) using the cationic dummy atom approach. Based on our computational results, we hypothesized that introducing a hydroxyl group to the inhibitor could improve its potency. Synthesis and testing of the hydroxyl-containing analog as a BoNTA endopeptidase inhibitor showed a twofold improvement in inhibitory potency (Kiapp of 3.8±0.8 µM) with a relatively small increase in molecular weight (16 Da). The results offer an improved template for further optimization of BoNTA endopeptidase inhibitors and demonstrate the effectiveness of the cationic dummy atom approach in the design and optimization of zinc protease inhibitors.
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Affiliation(s)
- Jing Tang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Jewn Giew Park
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Charles B. Millard
- Division of Biochemistry, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - James J. Schmidt
- Department of Cell Biology and Biochemistry, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (JS); (Y-PP)
| | - Yuan-Ping Pang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
- * To whom correspondence should be addressed. E-mail: (JS); (Y-PP)
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30
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Eubanks LM, Hixon MS, Jin W, Hong S, Clancy CM, Tepp WH, Baldwin MR, Malizio CJ, Goodnough MC, Barbieri JT, Johnson EA, Boger DL, Dickerson TJ, Janda KD. An in vitro and in vivo disconnect uncovered through high-throughput identification of botulinum neurotoxin A antagonists. Proc Natl Acad Sci U S A 2007; 104:2602-7. [PMID: 17293454 PMCID: PMC1815229 DOI: 10.1073/pnas.0611213104] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Among the agents classified as "Category A" by the U.S. Centers for Disease Control and Prevention, botulinum neurotoxin (BoNT) is the most toxic protein known, with microgram quantities of the protein causing severe morbidity and mortality by oral or i.v. routes. Given that this toxin easily could be used in a potential bioterrorist attack, countermeasures urgently are needed to counteract the pathophysiology of BoNT. At a molecular level, BoNT exerts its paralytic effects through intracellular cleavage of vesicle docking proteins and subsequent organism-wide autonomic dysfunction. In an effort to identify small molecules that would disrupt the interaction between the light-chain metalloprotease of BoNT serotype A and its cognate substrate, a multifaceted screening effort was undertaken. Through the combination of in vitro screening against an optimized variant of the light chain involving kinetic analysis, cellular protection assays, and in vivo mouse toxicity assays, molecules that prevent BoNT/A-induced intracellular substrate cleavage and extend the time to death of animals challenged with lethal toxin doses were identified. Significantly, the two most efficacious compounds in vivo showed less effective activity in cellular assays intended to mimic BoNT exposure; indeed, one of these compounds was cytotoxic at concentrations three orders of magnitude below its effective dose in animals. These two lead compounds have surprisingly simple molecular structures and are readily amenable to optimization efforts for improvements in their biological activity. The findings validate the use of high-throughput screening protocols to define previously unrecognized chemical scaffolds for the development of therapeutic agents to treat BoNT exposure.
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Affiliation(s)
- Lisa M. Eubanks
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Mark S. Hixon
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Wei Jin
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Sukwon Hong
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Colin M. Clancy
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - William H. Tepp
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - Michael R. Baldwin
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226; and
| | | | | | - Joseph T. Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226; and
| | - Eric A. Johnson
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - Dale L. Boger
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Tobin J. Dickerson
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
- **To whom correspondence may be addressed. E-mail: or
| | - Kim D. Janda
- Departments of *Chemistry and
- Immunology
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
- **To whom correspondence may be addressed. E-mail: or
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Eubanks LM, Dickerson TJ, Janda KD. Technological advancements for the detection of and protection against biological and chemical warfare agents. Chem Soc Rev 2007; 36:458-70. [PMID: 17325785 DOI: 10.1039/b615227a] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There is a growing need for technological advancements to combat agents of chemical and biological warfare, particularly in the context of the deliberate use of a chemical and/or biological warfare agent by a terrorist organization. In this tutorial review, we describe methods that have been developed both for the specific detection of biological and chemical warfare agents in a field setting, as well as potential therapeutic approaches for treating exposure to these toxic species. In particular, nerve agents are described as a typical chemical warfare agent, and the two potent biothreat agents, anthrax and botulinum neurotoxin, are used as illustrative examples of potent weapons for which countermeasures are urgently needed.
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Affiliation(s)
- Lisa M Eubanks
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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