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Saricaoglu B, Gültekin Subaşı B, Karbancioglu-Guler F, Lorenzo JM, Capanoglu E. Phenolic compounds as natural microbial toxin detoxifying agents. Toxicon 2023; 222:106989. [PMID: 36509264 DOI: 10.1016/j.toxicon.2022.106989] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022]
Abstract
Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.
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Affiliation(s)
- Beyza Saricaoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Büşra Gültekin Subaşı
- Hafik Kamer Ornek Vocational School, Sivas Cumhuriyet University, 58140, Sivas, Turkey
| | - Funda Karbancioglu-Guler
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Jose Manuel Lorenzo
- Centro Tecnológico de La Carne de Galicia, Parque Tecnológico de Galicia, Avd. Galicia nº 4, San Cibrao das Viñas, 32900 Ourense, Spain; Universidade de Vigo, Área de Tecnoloxía dos Alimentos, Facultade de Ciencias, 32004 Ourense, Spain
| | - Esra Capanoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey.
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2
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Lin L, Olson ME, Eubanks LM, Janda KD. Strategies to Counteract Botulinum Neurotoxin A: Nature's Deadliest Biomolecule. Acc Chem Res 2019; 52:2322-2331. [PMID: 31322847 DOI: 10.1021/acs.accounts.9b00261] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Botulinum neurotoxin serotype A (BoNT/A), marketed commercially as Botox, is the most toxic substance known to man with an estimated intravenous lethal dose (LD50) of 1-2 ng/kg in humans. Despite its widespread use in cosmetic and medicinal applications, no postexposure therapeutics are available for the reversal of intoxication in the event of medical malpractice or bioterrorism. Accordingly, the Centers for Disease Control and Prevention categorizes BoNT/A as a Category A pathogen, posing the highest risk to national security and public health as a result of the ease with which BoNT/A can be weaponized and disseminated. BoNT/A-mediated lethality results from neurons impeded from releasing acetylcholine, which ultimately causes muscle paralysis and possible death by asphyxiation with the loss of diaphragm function. Currently, the only available respite for BoNT/A poisoning is antibody-based therapy; however, this intervention is only effective within 12-24 h postexposure. Small molecule therapeutics remain the only opportunity to reverse BoNT/A intoxication after neuronal poisoning and are urgently needed. Nevertheless, no small molecule BoNT/A inhibitors have reached the clinic or even advanced to clinical trials. This Account highlights the accomplishments and existing challenges facing BoNT/A drug discovery today. Using the comprehensive body of work from our laboratory, we illustrate our nearly two-decade endeavor to discover a clinically relevant BoNT/A inhibitor. Specifically, a discussion on the identification and characterization of new chemical leads, the development of in vitro and in vivo assays, and pertinent discoveries in BoNT/A structural biology related to small molecule inhibition is presented. Lead discovery efforts in our laboratory have leveraged both in vitro high-throughput screening and rational design, and an array of mechanistic strategies for inhibiting BoNT/A has been discovered, including noncovalent inhibition, metal-binding active site inhibition, covalent inhibition, and α- and β-exosite inhibition. We contrast the strengths and weaknesses of each of these mechanistic strategies and propose the most favorable approach for success. Finally, we discuss multiple serendipitous discoveries of antibotulism small molecules with alternative mechanisms of action. Remaining challenges facing clinically relevant BoNT/A inhibition are presented and analyzed, including the current inability to reconcile toxin half-life (months to greater than one year) in neurons with in vivo pharmaceutical lifetimes and reoccurring inconsistencies between in vitro, cellular, and in vivo translation. Our Account of BoNT/A chemical research emphasizes the present accomplishments and critically analyzes the remaining obstacles for drug discovery. Importantly, we call for an increased focus on the discovery of safe and effective covalent inhibitors of BoNT/A that compete with the inherent half-life of the toxin.
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Affiliation(s)
- Lucy Lin
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Margaret E. Olson
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lisa M. Eubanks
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Kim D. Janda
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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3
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Ambrin G, Kumar R, Singh BR. Differential endopeptidase activity of different forms of type A botulinum neurotoxin: A unique relationship between the size of the substrate and activity of the enzyme. Toxicon 2018; 144:34-41. [PMID: 29309744 DOI: 10.1016/j.toxicon.2017.12.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 12/27/2017] [Accepted: 12/30/2017] [Indexed: 10/18/2022]
Abstract
Botulinum neurotoxins (BoNTs; serotypes A-G) are metalloproteases, which cleave and inactivate cellular proteins essential for neurotransmitter release. In bacterial cultures, BoNTs are secreted as a complex of the neurotoxin and a group of neurotoxin associated proteins (NAPs). Under physiological condition (pH 7.4), this complex is believed to be dissociated to separate the neurotoxin from NAPs. BoNT consists of a 50 kDa light (L) chain (LC or catalytic domain) and a 100 kDa heavy (H) chain (or HC) linked through a disulfide bond and other non-covalent interactions. The cell intoxication involves three major steps; binding, membrane translocation and inhibition of neurotransmitter release. The last step of intoxication, endopeptidase activity, is very unique and specific that can be used for detection of the complex and isolated forms of the toxin. A fluorescent tag-labeled synthetic peptide (SNAPtide) derived from a segment of SNAP-25, an intracellular substrate of BoNT/A, is used to detect and assay the endopeptidase activity of BoNT/A. The detection of the signal is based on the change in the fluorescence energy transfer after selective cleavage of the peptide by the BoNT/A. In this report, we demonstrate that SNAPtide as a commonly used substrate widely differ in reaction with BoNT/A complex, BoNT/A, and BoNT/A light chain. These findings have implications for assays used in detection, and in screening potential inhibitors.
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Affiliation(s)
- Ghuncha Ambrin
- Department of Chemistry and Biochemistry, University of Massachusetts, North Dartmouth, MA, 02747, USA
| | - Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA
| | - Bal Ram Singh
- Department of Chemistry and Biochemistry, University of Massachusetts, North Dartmouth, MA, 02747, USA; Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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4
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Xue S, Seki H, Remes M, Šilhár P, Janda K. Examination of α-exosite inhibitors against Botulinum neurotoxin A protease through structure-activity relationship studies of chicoric acid. Bioorg Med Chem Lett 2017; 27:4956-4959. [PMID: 29050781 PMCID: PMC5667901 DOI: 10.1016/j.bmcl.2017.10.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 12/20/2022]
Abstract
Botulinum neurotoxins (BoNT) are among the most toxic known substances and currently there are no effective treatments for intraneuronal BoNT intoxication. Chicoric acid (ChA) was previously reported as a BoNT/A inhibitor that binds to the enzyme's α-exosite. Herein, we report the synthesis and structure-activity relationships (SARs) of a series of ChA derivatives, which revealed essential binding interactions between ChA and BoNT/A. Moreover, several ChA-based inhibitors with improved potency against the BoNT/A were discovered.
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Affiliation(s)
- Song Xue
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Hajime Seki
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Marek Remes
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Peter Šilhár
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Kim Janda
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Worm Institute for Research Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States.
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5
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Bremer PT, Pellett S, Carolan JP, Tepp WH, Eubanks LM, Allen KN, Johnson EA, Janda KD. Metal Ions Effectively Ablate the Action of Botulinum Neurotoxin A. J Am Chem Soc 2017; 139:7264-7272. [PMID: 28475321 PMCID: PMC5612488 DOI: 10.1021/jacs.7b01084] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Botulinum neurotoxin serotype A (BoNT/A) causes a debilitating and potentially fatal illness known as botulism. The toxin is also a bioterrorism threat, yet no pharmacological antagonist to counteract its effects has reached clinical approval. Existing strategies to negate BoNT/A intoxication have looked to antibodies, peptides, or organic small molecules as potential therapeutics. In this work, a departure from the traditional drug discovery mindset was pursued, in which the enzyme's susceptibility to metal ions was exploited. A screen of a series of metal salts showed marked inhibitory activity of group 11 and 12 metals against the BoNT/A light chain (LC) protease. Enzyme kinetics revealed that copper (I) and (II) cations displayed noncompetitive inhibition of the LC (Ki ≈ 1 μM), while mercury (II) cations were 10-fold more potent. Crystallographic and mutagenesis studies elucidated a key binding interaction between Cys165 on BoNT/A LC and the inhibitory metals. As potential copper prodrugs, ligand-copper complexes were examined in a cell-based model and were found to prevent BoNT/A cleavage of the endogenous protein substrate, SNAP-25, even at low μM concentrations of complexes. Further investigation of the complexes suggested a bioreductive mechanism causing intracellular release of copper, which directly inhibited the BoNT/A protease. In vivo experiments demonstrated that copper (II) dithiocarbamate and bis(thiosemicarbazone) complexes could delay BoNT/A-mediated lethality in a rodent model, indicating their potential for treating the harmful effects of BoNT/A intoxication. Our studies illustrate that metals can be therapeutically viable enzyme inhibitors; moreover, enzymes that share homology with BoNT LCs may be similarly targeted with metals.
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Affiliation(s)
- Paul T. Bremer
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - James P. Carolan
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - William H. Tepp
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - Lisa M. Eubanks
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Karen N. Allen
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - Eric A. Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - Kim D. Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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6
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Pirazzini M, Rossetto O. Challenges in searching for therapeutics against Botulinum Neurotoxins. Expert Opin Drug Discov 2017; 12:497-510. [DOI: 10.1080/17460441.2017.1303476] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Minnow YV, Goldberg R, Tummalapalli SR, Rotella DP, Goodey NM. Mechanism of inhibition of botulinum neurotoxin type A light chain by two quinolinol compounds. Arch Biochem Biophys 2017; 618:15-22. [DOI: 10.1016/j.abb.2017.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/06/2017] [Accepted: 01/12/2017] [Indexed: 11/26/2022]
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Affiliation(s)
- Megan Garland
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
| | - Sebastian Loscher
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
| | - Matthew Bogyo
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
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9
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Yalamanchili C, Manda VK, Chittiboyina AG, Guernieri RL, Harrell WA, Webb RP, Smith LA, Khan IA. Utilizing Ayurvedic literature for the identification of novel phytochemical inhibitors of botulinum neurotoxin A. JOURNAL OF ETHNOPHARMACOLOGY 2017; 197:211-217. [PMID: 27469199 DOI: 10.1016/j.jep.2016.07.069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/20/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Ayurveda, an ancient holistic system of health care practiced on the Indian subcontinent, utilizes a number of multi-plant formulations and is considered by many as a potential source for novel treatments, as well as the identification of new drugs. Our aim is to identify novel phytochemicals for the inhibition of bacterial exotoxin, botulinum neurotoxin A (BoNT/A) based on Ayurvedic literature. BoNT/A is released by Clostridium species, which when ingested, inhibits the release of acetylcholine by concentrating at the neuromuscular junction and causes flaccid paralysis, resulting in a condition termed as botulism, and may also lead to death due to respiratory arrest. METHODS Fifteen plants were selected from the book 'Diagnosis and treatment of diseases in Ayurveda' by Vaidya Bhagwan Dash and Lalitesh Kashyap, based on their frequency of use in the formulations used for the treatment of six diseases with neuromuscular symptoms similar to botulism. Phytochemicals from these plants were screened using in silico, and in vitro methods. Structures of 570 reported phytochemicals from 14 plants were docked inside six reported BoNT/A light chain crystal structures using ensemble docking module in Maestro (Schrödinger, LLE). RESULTS From the docking scores and structural diversity, nine compounds including acoric acid 1, three flavonoids, three coumarins derivatives, one kava lactone were selected and screened using an in vitro HPLC-based protease assay. The bioassay results showed that several compounds possess BoNT/A LC inhibition of 50-60% when compared to positive controls NSC 84094 and CB7967495 (80-95%). CONCLUSION Further testing of the active compounds identified from Ayurvedic literature and structure-activity studies of acoric acid 1 using more sensitive bioassays is under way. The identification of acoric acid 1, a novel scaffold against BoNT/A, exemplifies the utility of Ayurvedic literature for the discovery of novel drug leads.
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Affiliation(s)
- Chinni Yalamanchili
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS 38677, USA; Divison of Pharmacognosy, Department of BioMolecular Sciences, The University of Mississippi, University, MS 38677, USA
| | - Vamshi K Manda
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS 38677, USA
| | - Amar G Chittiboyina
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS 38677, USA
| | - Rebecca L Guernieri
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - William A Harrell
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - Robert P Webb
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - Leonard A Smith
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - Ikhlas A Khan
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS 38677, USA; Divison of Pharmacognosy, Department of BioMolecular Sciences, The University of Mississippi, University, MS 38677, USA.
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10
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Bremer PT, Adler M, Phung CH, Singh AK, Janda KD. Newly Designed Quinolinol Inhibitors Mitigate the Effects of Botulinum Neurotoxin A in Enzymatic, Cell-Based, and ex Vivo Assays. J Med Chem 2017; 60:338-348. [PMID: 27966961 DOI: 10.1021/acs.jmedchem.6b01393] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Botulinum neurotoxin A (BoNT/A) is one of the most deadly toxins and is the etiological agent of the potentially fatal condition, botulism. Herein, we investigated 8-hydroxyquinoline (quinolin-8-ol) as a potential inhibitor scaffold for preventing the deadly neurochemical effects of the toxin. Quinolinols are known chelators that can disrupt the BoNT/A metalloprotease zinc-containing active site, thus impeding its proteolysis of the endogenous protein substrate, synaptosomal-associated protein 25 (SNAP-25). By use of this information, the structure-activity relationship (SAR) of the quinolinol-5-sulfonamide scaffold was explored through preparation of a crude sulfonamide library and evaluation of the library in a BoNT/A LC enzymatic assay. Potency optimization of the sulfonamide hit compounds was undertaken as informed by docking studies, granting a lead compound with a submicromolar Ki. These quinolinol analogues demonstrated inhibitory activity in a cell-based model for SNAP-25 cleavage and an ex vivo assay for BoNT/A-mediated muscle paralysis.
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Affiliation(s)
- Paul T Bremer
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Michael Adler
- Neurobehavioral Toxicology Branch, Analytical Toxicology Division, U.S. Army Medical Research Institute of Chemical Defense , 2900 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5400, United States
| | - Cecilia H Phung
- Neurobehavioral Toxicology Branch, Analytical Toxicology Division, U.S. Army Medical Research Institute of Chemical Defense , 2900 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5400, United States
| | - Ajay K Singh
- Neurobehavioral Toxicology Branch, Analytical Toxicology Division, U.S. Army Medical Research Institute of Chemical Defense , 2900 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5400, United States
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, 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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11
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Bremer PT, Xue S, Janda KD. Picolinic acids as β-exosite inhibitors of botulinum neurotoxin A light chain. Chem Commun (Camb) 2016; 52:12521-12524. [PMID: 27722252 PMCID: PMC5085802 DOI: 10.1039/c6cc06749b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In developing small-molecule inhibitors of botulinum neurotoxin serotype A light chain (BoNT/A LC), substituted picolinic acids were identified. Extensive investigation into the SAR of the picolinic acid scaffold revealed 5-(1-butyl-4-chloro-1H-indol-2-yl)picolinic acid (CBIP), which possessed low micromolar activity against BoNT/A. Kinetic and docking studies demonstrated binding of CBIP to the β-exosite: a largely unexplored site on the LC that holds therapeutic relevance for botulism treatment.
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Affiliation(s)
- Paul T Bremer
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Song Xue
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Kim D Janda
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
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12
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Bompiani KM, Caglič D, Krutein MC, Benoni G, Hrones M, Lairson LL, Bian H, Smith GR, Dickerson TJ. High-Throughput Screening Uncovers Novel Botulinum Neurotoxin Inhibitor Chemotypes. ACS COMBINATORIAL SCIENCE 2016; 18:461-74. [PMID: 27314875 DOI: 10.1021/acscombsci.6b00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Botulism is caused by potent and specific bacterial neurotoxins that infect host neurons and block neurotransmitter release. Treatment for botulism is limited to administration of an antitoxin within a short time window, before the toxin enters neurons. Alternatively, current botulism drug development targets the toxin light chain, which is a zinc-dependent metalloprotease that is delivered into neurons and mediates long-term pathology. Several groups have identified inhibitory small molecules, peptides, or aptamers, although no molecule has advanced to the clinic due to a lack of efficacy in advanced models. Here we used a homogeneous high-throughput enzyme assay to screen three libraries of drug-like small molecules for new chemotypes that modulate recombinant botulinum neurotoxin light chain activity. High-throughput screening of 97088 compounds identified numerous small molecules that activate or inhibit metalloprotease activity. We describe four major classes of inhibitory compounds identified, detail their structure-activity relationships, and assess their relative inhibitory potency. A previously unreported chemotype in any context of enzyme inhibition is described with potent submicromolar inhibition (Ki = 200-300 nM). Additional detailed kinetic analyses and cellular cytotoxicity assays indicate the best compound from this series is a competitive inhibitor with cytotoxicity values around 4-5 μM. Given the potency and drug-like character of these lead compounds, further studies, including cellular activity assays and DMPK analysis, are justified.
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Affiliation(s)
- Kristin M. Bompiani
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Dejan Caglič
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Michelle C. Krutein
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Galit Benoni
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Morgan Hrones
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Luke L. Lairson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Haiyan Bian
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Tobin J. Dickerson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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13
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Zhou Y, McGillick BE, Teng YHG, Haranahalli K, Ojima I, Swaminathan S, Rizzo RC. Identification of small molecule inhibitors of botulinum neurotoxin serotype E via footprint similarity. Bioorg Med Chem 2016; 24:4875-4889. [PMID: 27543389 DOI: 10.1016/j.bmc.2016.07.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 07/15/2016] [Accepted: 07/16/2016] [Indexed: 11/15/2022]
Abstract
Botulinum neurotoxins (BoNT) are among the most poisonous substances known, and of the 7 serotypes (A-G) identified thus far at least 4 can cause death in humans. The goal of this work was identification of inhibitors that specifically target the light chain catalytic site of the highly pathogenic but lesser-studied E serotype (BoNT/E). Large-scale computational screening, employing the program DOCK, was used to perform atomic-level docking of 1.4 million small molecules to prioritize those making favorable interactions with the BoNT/E site. In particular, 'footprint similarity' (FPS) scoring was used to identify compounds that could potentially mimic features on the known substrate tetrapeptide RIME. Among 92 compounds purchased and experimentally tested, compound C562-1101 emerged as the most promising hit with an apparent IC50 value three-fold more potent than that of the first reported BoNT/E small molecule inhibitor NSC-77053. Additional analysis showed the predicted binding pose of C562-1101 was geometrically and energetically stable over an ensemble of structures generated by molecular dynamic simulations and that many of the intended interactions seen with RIME were maintained. Several analogs were also computationally designed and predicted to have further molecular mimicry thereby demonstrating the potential utility of footprint-based scoring protocols to help guide hit refinement.
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Affiliation(s)
- Yuchen Zhou
- Department of Applied Mathematics & Statistics, Stony Brook University, Stony Brook, NY 11794, United States
| | - Brian E McGillick
- Graduate Program in Biochemistry & Structural Biology, Stony Brook University, Stony Brook, NY 11794, United States; Biology Department, Brookhaven National Laboratory, Upton, NY 11973, United States
| | - Yu-Han Gary Teng
- Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY 11794, United States; Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States
| | | | - Iwao Ojima
- Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY 11794, United States; Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States
| | | | - Robert C Rizzo
- Department of Applied Mathematics & Statistics, Stony Brook University, Stony Brook, NY 11794, United States; Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY 11794, United States; Laufer Center for Physical & Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States.
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14
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Seki H, Xue S, Pellett S, Šilhár P, Johnson EA, Janda KD. Cellular Protection of SNAP-25 against Botulinum Neurotoxin/A: Inhibition of Thioredoxin Reductase through a Suicide Substrate Mechanism. J Am Chem Soc 2016; 138:5568-75. [PMID: 27070533 PMCID: PMC4881748 DOI: 10.1021/jacs.5b12929] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Botulium neurotoxins (BoNTs) are among the most lethal toxins known to man. They are comprised of seven serotypes with BoNT/A being the most deadly; yet, there is no approved therapeutic for their intoxication or one that has even advanced to clinical trials. Botulinum neurotoxicity is ultimately governed through light chain (LC) protease SNARE protein cleavage leading to a loss of neurotransmitter release. Pharmacological attempts to ablate BoNT/A intoxication have sought to either nullify cellular toxin entry or critical biochemical junctions found within its intricate mechanism of action. In these regards, reports have surfaced of nonpeptidic small molecule inhibitors, but few have demonstrated efficacy in neutralizing cellular toxicity, a key prerequisite before rodent lethality studies can be initiated. On the basis of a lead discovered in our BoNT/A cellular assay campaign, we investigated a family of N-hydroxysuccinimide inhibitors grounded upon structure activity relationship (SAR) fundamentals. Molecules stemming from this SAR exercise were theorized to be protease inhibitors. However, this proposition was overturned on the basis of extensive kinetic analysis. Unexpectedly, inhibitor data pointed to thioredoxin reductase (TrxR), an essential component required for BoNT protease translocation. Also unforeseen was the inhibitors' mechanism of action against TrxR, which was found to be brokered through a suicide-mechanism utilizing quinone methide as the inactivating element. This new series of TrxR inhibitors provides an alternative means to negate the etiological agent responsible for BoNT intoxication, the LC protease.
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Affiliation(s)
| | | | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin , 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | | | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin , 1550 Linden Drive, Madison, Wisconsin 53706, United States
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15
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Seki H, Xue S, Hixon MS, Pellett S, Remes M, Johnson EA, Janda KD. Toward the discovery of dual inhibitors for botulinum neurotoxin A: concomitant targeting of endocytosis and light chain protease activity. Chem Commun (Camb) 2015; 51:6226-9. [PMID: 25759983 DOI: 10.1039/c5cc00677e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dyngo-4a™ has been found to be an endocytic inhibitor of BoNT/A neurotoxicity through dynamin inhibition. Herein, we demonstrate this molecule to have a previously unrecognized dual activity against BoNT/A, dynamin-protease inhibition. To establish the importance of this dual activity, detailed kinetic analysis of Dyngo-4a's inhibition of BoNT/A metalloprotease as well as cellular and animal toxicity studies have been described. The research presented is the first polypharmacological approach to counteract BoNT/A intoxication.
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Affiliation(s)
- Hajime Seki
- Departments of Chemistry and Immunology and Microbial Sciences, 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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Guo J, Wang J, Gao S, Ji B, Waichi Chan E, Chen S. Substrate-based inhibitors exhibiting excellent protective and therapeutic effects against Botulinum Neurotoxin A intoxication. Sci Rep 2015; 5:16981. [PMID: 26584873 PMCID: PMC4653808 DOI: 10.1038/srep16981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/22/2015] [Indexed: 12/18/2022] Open
Abstract
Potent inhibitors to reverse Botulinum neurotoxins (BoNTs) activity in neuronal cells are currently not available. A better understanding of the substrate recognition mechanism of BoNTs enabled us to design a novel class of peptide inhibitors which were derivatives of the BoNT/A substrate, SNAP25. Through a combination of in vitro, cellular based, and in vivo mouse assays, several potent inhibitors of approximately one nanomolar inhibitory strength both in vitro and in vivo have been identified. These compounds represent the first set of inhibitors that exhibited full protection against BoNT/A intoxication in mice model with undetectable toxicity. Our findings validated the hypothesis that a peptide inhibitor targeting the two BoNT structural regions which were responsible for substrate recognition and cleavage respectively could exhibit excellent inhibitory effect, thereby providing insight on future development of more potent inhibitors against BoNTs.
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Affiliation(s)
- Jiubiao Guo
- Shenzhen Key lab for Food Biological Safety Control, Food Safety and Technology Research Center, Hong Kong PolyU Shen Zhen Research Institute, Shenzhen, P. R. China
- State Key Lab of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jinglin Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Fengtai District, Beijing, People’s Republic of China
| | - Shan Gao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Fengtai District, Beijing, People’s Republic of China
| | - Bin Ji
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Fengtai District, Beijing, People’s Republic of China
| | - Edward Waichi Chan
- Shenzhen Key lab for Food Biological Safety Control, Food Safety and Technology Research Center, Hong Kong PolyU Shen Zhen Research Institute, Shenzhen, P. R. China
- State Key Lab of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Sheng Chen
- Shenzhen Key lab for Food Biological Safety Control, Food Safety and Technology Research Center, Hong Kong PolyU Shen Zhen Research Institute, Shenzhen, P. R. China
- State Key Lab of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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17
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Kiris E, Burnett JC, Nuss JE, Wanner LM, Peyser BD, Du HT, Gomba GY, Kota KP, Panchal RG, Gussio R, Kane CD, Tessarollo L, Bavari S. SRC family kinase inhibitors antagonize the toxicity of multiple serotypes of botulinum neurotoxin in human embryonic stem cell-derived motor neurons. Neurotox Res 2015; 27:384-98. [PMID: 25782580 PMCID: PMC4455898 DOI: 10.1007/s12640-015-9526-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 03/05/2015] [Indexed: 02/07/2023]
Abstract
Botulinum neurotoxins (BoNTs), the causative agents of botulism, are potent inhibitors of neurotransmitter release from motor neurons. There are currently no drugs to treat BoNT intoxication after the onset of the disease symptoms. In this study, we explored how modulation of key host pathways affects the process of BoNT intoxication in human motor neurons, focusing on Src family kinase (SFK) signaling. Motor neurons derived from human embryonic stem (hES) cells were treated with a panel of SFK inhibitors and intoxicated with BoNT serotypes A, B, or E (which are responsible for >95 % of human botulism cases). Subsequently, it was found that bosutinib, dasatinib, KX2-391, PP1, PP2, Src inhibitor-1, and SU6656 significantly antagonized all three of the serotypes. Furthermore, the data indicated that the treatment of hES-derived motor neurons with multiple SFK inhibitors increased the antagonistic effect synergistically. Mechanistically, the small molecules appear to inhibit BoNTs by targeting host pathways necessary for intoxication and not by directly inhibiting the toxins' proteolytic activity. Importantly, the identified inhibitors are all well-studied with some in clinical trials while others are FDA-approved drugs. Overall, this study emphasizes the importance of targeting host neuronal pathways, rather than the toxin's enzymatic components, to antagonize multiple BoNT serotypes in motor neurons.
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Affiliation(s)
- Erkan Kiris
- Geneva Foundation, Tacoma, WA, USA
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
- Neural Development Section, Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
| | - James C. Burnett
- Leidos Biomedical Research, Inc., Computational Drug Development Group (CDDG), NCI, Frederick, MD 21702, USA
- CDDG, Developmental Therapeutics Program, NCI, Frederick, MD 21702, USA
| | - Jonathan E. Nuss
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Laura M. Wanner
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Brian D. Peyser
- CDDG, Developmental Therapeutics Program, NCI, Frederick, MD 21702, USA
| | - Hao T. Du
- Neural Development Section, Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
| | - Glenn Y. Gomba
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Krishna P. Kota
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Rekha G. Panchal
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Rick Gussio
- CDDG, Developmental Therapeutics Program, NCI, Frederick, MD 21702, USA
| | - Christopher D. Kane
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
- Henry M. Jackson Foundation, Bethesda, MD, USA
- DoD Biotechnology High Performance Computing Software Applications Institute (BHSAI), Telemedicine and Advanced Technology Research Center (TATRC), US Army Medical Research and Materiel Command (USAMRMC), Frederick, MD 2170, USA
| | - Lino Tessarollo
- Neural Development Section, Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
| | - Sina Bavari
- Department of Molecular and Translational Sciences, US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
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18
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19
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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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20
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Structural insight into exosite binding and discovery of novel exosite inhibitors of botulinum neurotoxin serotype A through in silico screening. J Comput Aided Mol Des 2014; 28:765-78. [PMID: 24958623 DOI: 10.1007/s10822-014-9758-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 05/26/2014] [Indexed: 01/25/2023]
Abstract
Botulinum neurotoxin serotype A (BoNT/A) is the most lethal toxin among the Tier 1 Select Agents. Development of potent and selective small molecule inhibitors against BoNT/A zinc metalloprotease remains a challenging problem due to its exceptionally large substrate binding surface and conformational plasticity. The exosites of the catalytic domain of BoNT/A are intriguing alternative sites for small molecule intervention, but their suitability for inhibitor design remains largely unexplored. In this study, we employed two recently identified exosite inhibitors, D-chicoric acid and lomofungin, to probe the structural features of the exosites and molecular mechanisms of synergistic inhibition. The results showed that D-chicoric acid favors binding at the α-exosite, whereas lomofungin preferentially binds at the β-exosite by mimicking the substrate β-sheet binding interaction. Molecular dynamics simulations and binding interaction analysis of the exosite inhibitors with BoNT/A revealed key elements and hotspots that likely contribute to the inhibitor binding and synergistic inhibition. Finally, we performed database virtual screening for novel inhibitors of BoNT/A targeting the exosites. Hits C1 and C2 showed non-competitive inhibition and likely target the α- and β-exosites, respectively. The identified exosite inhibitors may provide novel candidates for structure-based development of therapeutics against BoNT/A intoxication.
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21
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Bremer PT, Hixon MS, Janda KD. Benzoquinones as inhibitors of botulinum neurotoxin serotype A. Bioorg Med Chem 2014; 22:3971-81. [PMID: 24984937 DOI: 10.1016/j.bmc.2014.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 02/06/2023]
Abstract
Although botulinum neurotoxin serotype A (BoNT/A) is known for its use in cosmetics, it causes a potentially fatal illness, botulism, and can be used as a bioterror weapon. Many compounds have been developed that inhibit the BoNTA zinc-metalloprotease light chain (LC), however, none of these inhibitors have advanced to clinical trials. In this study, a fragment-based approach was implemented to develop novel covalent inhibitors of BoNT/A LC. First, electrophilic fragments were screened against BoNT/A LC, and benzoquinone (BQ) derivatives were found to be active. In kinetic studies, BQ compounds acted as irreversible inhibitors that presumably covalently modify cysteine 165 of BoNT/A LC. Although most BQ derivatives were highly reactive toward glutathione in vitro, a few compounds such as natural product naphthazarin displayed low thiol reactivity and good BoNT/A inhibition. In order to increase the potency of the BQ fragment, computational docking studies were employed to elucidate a scaffold that could bind to sites adjacent to Cys165 while positioning a BQ fragment at Cys165 for covalent modification; 2-amino-N-arylacetamides met these criteria and when linked to BQ displayed at least a 20-fold increase in activity to low μM IC₅₀ values. Unlike BQ alone, the linked-BQ compounds demonstrated only weak irreversible inhibition and therefore acted mainly as non-covalent inhibitors. Further kinetic studies revealed a mutual exclusivity of BQ covalent inactivation and competitive inhibitor binding to sites adjacent to Cys165, refuting the viability of the current strategy for developing more potent irreversible BoNT/A inhibitors. The highlights of this study include the discovery of BQ compounds as irreversible BoNT/A inhibitors and the rational design of low μM IC50 competitive inhibitors that depend on the BQ moiety for activity.
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Affiliation(s)
- Paul T Bremer
- Departments of Chemistry and Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Mark S Hixon
- Discovery Biology, Takeda San Diego, Inc., 10410 Science Center Drive, San Diego, CA 92121, USA
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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22
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Videnović M, Opsenica DM, Burnett J, Gomba L, Nuss JE, Selaković Ž, Konstantinović J, Krstić M, Šegan S, Zlatović M, Sciotti RJ, Bavari S, Šolaja BA. Second generation steroidal 4-aminoquinolines are potent, dual-target inhibitors of the botulinum neurotoxin serotype A metalloprotease and P. falciparum malaria. J Med Chem 2014; 57:4134-53. [PMID: 24742203 PMCID: PMC4032193 DOI: 10.1021/jm500033r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Indexed: 01/25/2023]
Abstract
Significantly more potent second generation 4-amino-7-chloroquinoline (4,7-ACQ) based inhibitors of the botulinum neurotoxin serotype A (BoNT/A) light chain were synthesized. Introducing an amino group at the C(3) position of the cholate component markedly increased potency (IC50 values for such derivatives ranged from 0.81 to 2.27 μM). Two additional subclasses were prepared: bis(steroidal)-4,7-ACQ derivatives and bis(4,7-ACQ)cholate derivatives; both classes provided inhibitors with nanomolar-range potencies (e.g., the Ki of compound 67 is 0.10 μM). During BoNT/A challenge using primary neurons, select derivatives protected SNAP-25 by up to 89%. Docking simulations were performed to rationalize the compounds' in vitro potencies. In addition to specific residue contacts, coordination of the enzyme's catalytic zinc and expulsion of the enzyme's catalytic water were a consistent theme. With respect to antimalarial activity, the compounds provided better IC90 activities against chloroquine resistant (CQR) malaria than CQ, and seven compounds were more active than mefloquine against CQR strain W2.
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Affiliation(s)
- Milica Videnović
- Faculty
of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - Dejan M. Opsenica
- Institute
of Chemistry, Technology, and Metallurgy, University of Belgrade, Njegoseva 12, 11000 Belgrade, Serbia
| | - James
C. Burnett
- Computational
Drug Development Group, Leidos Biomedical
Research, Inc., FNLCR at Frederick, P.O.
Box B, Frederick, Maryland 21701, United States
| | - Laura Gomba
- Department
of Bacteriology, United States Army Medical
Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, Maryland 21702, United States
| | - Jonathan E. Nuss
- Department
of Bacteriology, United States Army Medical
Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, Maryland 21702, United States
| | - Života Selaković
- Faculty
of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - Jelena Konstantinović
- Faculty
of Chemistry Innovative Centre, Studentski trg 12-16, 11158 Belgrade, Serbia
| | - Maja Krstić
- Faculty
of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - Sandra Šegan
- Institute
of Chemistry, Technology, and Metallurgy, University of Belgrade, Njegoseva 12, 11000 Belgrade, Serbia
| | - Mario Zlatović
- Faculty
of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - Richard J. Sciotti
- Division
of Experimental Therapeutics, Walter Reed
Army Institute of Research, Silver
Spring, Maryland 20910, United States
| | - Sina Bavari
- Target
Discovery and Experimental Microbiology, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, Maryland 21702, United States
| | - Bogdan A. Šolaja
- Faculty
of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
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23
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Identification of exosite-targeting inhibitors of anthrax lethal factor by high-throughput screening. ACTA ACUST UNITED AC 2014; 19:875-82. [PMID: 22840775 DOI: 10.1016/j.chembiol.2012.05.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/10/2012] [Accepted: 05/17/2012] [Indexed: 12/24/2022]
Abstract
Protease inhibitor discovery has focused almost exclusively on compounds that bind to the active site. Inhibitors targeting protease exosites, regions outside of the active site that influence catalysis, offer potential advantages of increased specificity but are difficult to systematically discover. Here, we describe an assay suitable for detecting exosite-targeting inhibitors of the metalloproteinase anthrax lethal factor (LF) based on cleavage of a full-length mitogen-activated protein kinase kinase (MKK) substrate. We used this assay to screen a small-molecule library and then subjected hits to a secondary screen to exclude compounds that efficiently blocked cleavage of a peptide substrate. We identified a compound that preferentially inhibited cleavage of MKKs compared with peptide substrates and could suppress LF-induced macrophage cytolysis. This approach should be generally applicable to the discovery of exosite-targeting inhibitors of many additional proteases.
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24
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Patel K, Cai S, Singh BR. Current strategies for designing antidotes against botulinum neurotoxins. Expert Opin Drug Discov 2014; 9:319-33. [DOI: 10.1517/17460441.2014.884066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Kruti Patel
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
| | - Shuowei Cai
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
| | - Bal Ram Singh
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
- Institute of Advanced Sciences and Prime Bio, Inc., Botulinum Research Center, 166 Chase Road, North Dartmouth, MA 02747, USA
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25
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Silhár P, Eubanks LM, Seki H, Pellett S, Javor S, Tepp WH, Johnson EA, Janda KD. Targeting botulinum A cellular toxicity: a prodrug approach. J Med Chem 2013; 56:7870-9. [PMID: 24127873 DOI: 10.1021/jm400873n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The botulinum neurotoxin light chain (LC) protease has become an important therapeutic target for postexposure treatment of botulism. Hydroxamic acid based small molecules have proven to be potent inhibitors of LC/A with nanomolar Ki values, yet they lack cellular activity conceivably due to low membrane permeability. To overcome this potential liability, we investigated two prodrug strategies, 1,4,2-dioxazole and carbamate, based on our 1-adamantylacetohydroxamic acid scaffold. The 1,4,2-dioxazole prodrug did not demonstrate cellular activity, however, carbamates exhibited cellular potency with the most active compound displaying an EC50 value of 20 μM. Cellular trafficking studies were conducted using a "fluorescently silent" prodrug that remained in this state until cellular uptake was complete, which allowed for visualization of the drug's release inside neuronal cells. In sum, this research sets the stage for future studies leveraging the specific targeting and delivery of these prodrugs, as well as other antibotulinum agents, into neuronal cells.
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Affiliation(s)
- Peter Silhár
- Departments of Chemistry and Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, and The Worm Institute for Research and Medicine, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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26
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Friedman M, Rasooly R. Review of the inhibition of biological activities of food-related selected toxins by natural compounds. Toxins (Basel) 2013; 5:743-75. [PMID: 23612750 PMCID: PMC3705290 DOI: 10.3390/toxins5040743] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/05/2013] [Accepted: 04/16/2013] [Indexed: 11/17/2022] Open
Abstract
There is a need to develop food-compatible conditions to alter the structures of fungal, bacterial, and plant toxins, thus transforming toxins to nontoxic molecules. The term 'chemical genetics' has been used to describe this approach. This overview attempts to survey and consolidate the widely scattered literature on the inhibition by natural compounds and plant extracts of the biological (toxicological) activity of the following food-related toxins: aflatoxin B1, fumonisins, and ochratoxin A produced by fungi; cholera toxin produced by Vibrio cholerae bacteria; Shiga toxins produced by E. coli bacteria; staphylococcal enterotoxins produced by Staphylococcus aureus bacteria; ricin produced by seeds of the castor plant Ricinus communis; and the glycoalkaloid α-chaconine synthesized in potato tubers and leaves. The reduction of biological activity has been achieved by one or more of the following approaches: inhibition of the release of the toxin into the environment, especially food; an alteration of the structural integrity of the toxin molecules; changes in the optimum microenvironment, especially pH, for toxin activity; and protection against adverse effects of the toxins in cells, animals, and humans (chemoprevention). The results show that food-compatible and safe compounds with anti-toxin properties can be used to reduce the toxic potential of these toxins. Practical applications and research needs are suggested that may further facilitate reducing the toxic burden of the diet. Researchers are challenged to (a) apply the available methods without adversely affecting the nutritional quality, safety, and sensory attributes of animal feed and human food and (b) educate food producers and processors and the public about available approaches to mitigating the undesirable effects of natural toxins that may present in the diet.
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Affiliation(s)
- Mendel Friedman
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, USDA, Albany, CA 94710, USA
| | - Reuven Rasooly
- Foodborne Contaminants Research Unit, Agricultural Research Service, USDA, Albany, CA 94710, USA; E-Mail:
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27
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Šilhár P, Lardy MA, Hixon MS, Shoemaker CB, Barbieri JT, Struss AK, Lively JM, Javor S, Janda KD. The C-terminus of Botulinum A Protease Has Profound and Unanticipated Kinetic Consequences Upon the Catalytic Cleft. ACS Med Chem Lett 2013; 4:283-287. [PMID: 23565325 DOI: 10.1021/ml300428s] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are among the most deadly poisons known though ironically, they also are of great therapeutic utility. A number of research programs have been initiated to discover small molecule inhibitors of BoNTs metalloprotease activity. Many, though not all of these programs have screened against a truncated and more stable form of the enzyme, that possess comparable catalytic properties to the full length enzyme. Interestingly, several classes of inhibitors notably the hydroxamates, display a large shift in potency between the two enzyme forms. In this report we compare the kinetics of active-site, alpha-exosite and beta-exosite inhibitors versus truncated and full length enzyme. Molecular dynamics simulations conducted with the truncated and homology models of the fully length BoNT LC/A indicate the flexibility of the C-terminus of the full length enzyme is responsible for the potency shifts of active-site proximally binding inhibitors while distal binding (alpha-exosite) inhibitors remain equipotent.
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Affiliation(s)
- Peter Šilhár
- 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
| | - Matthew A. Lardy
- Takeda California Inc., 10410 Science Center Drive, San Diego, California
92121, United States
| | - Mark S. Hixon
- Takeda California Inc., 10410 Science Center Drive, San Diego, California
92121, United States
| | - Charles B. Shoemaker
- Department
of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro
Road, North Grafton, Massachusetts 01536, United States
| | - Joseph T. Barbieri
- Department of Microbiology and
Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, United States
| | - Anjali K. Struss
- 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
| | - Jenny M. Lively
- 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
| | - Sacha Javor
- 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
| | - Kim D. Janda
- 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
- Worm Institute for Research
and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United
States
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28
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Toth S, Brueggmann EE, Oyler GA, Smith LA, Hines HB, Ahmed SA. Tyrosine phosphorylation of botulinum neurotoxin protease domains. Front Pharmacol 2012; 3:102. [PMID: 22675300 PMCID: PMC3366388 DOI: 10.3389/fphar.2012.00102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/07/2012] [Indexed: 01/17/2023] Open
Abstract
Botulinum neurotoxins are most potent of all toxins. Their N-terminal light chain domain (Lc) translocates into peripheral cholinergic neurons to exert its endoproteolytic action leading to muscle paralysis. Therapeutic development against these toxins is a major challenge due to their in vitro and in vivo structural differences. Although three-dimensional structures and reaction mechanisms are very similar, the seven serotypes designated A through G vastly vary in their intracellular catalytic stability. To investigate if protein phosphorylation could account for this difference, we employed Src-catalyzed tyrosine phosphorylation of the Lc of six serotypes namely LcA, LcB, LcC1, LcD, LcE, and LcG. Very little phosphorylation was observed with LcD and LcE but LcA, LcB, and LcG were maximally phosphorylated by Src. Phosphorylation of LcA, LcB, and LcG did not affect their secondary and tertiary structures and thermostability significantly. Phosphorylation of Y250 and Y251 made LcA resistant to autocatalysis and drastically reduced its kcat/Km for catalysis. A tyrosine residue present near the essential cysteine at the C-terminal tail of LcA, LcB, and LcG was readily phosphorylated in vitro. Inclusion of a competitive inhibitor protected Y426 of LcA from phosphorylation, shedding light on the role of the C-terminus in the enzyme’s substrate or product binding.
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Affiliation(s)
- Stephen Toth
- Integrated Toxicology Division, Department of Biochemistry and Cell Biology, United States Army Medical Research Institute of Infectious Diseases Fort Detrick, MD, USA
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29
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Structure-Based Drug Discovery for Botulinum Neurotoxins. Curr Top Microbiol Immunol 2012; 364:197-218. [DOI: 10.1007/978-3-642-33570-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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30
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Smoak EM, Fath KR, Barnaby SN, Grant VC, Banerjee IA. pH tunable self-assembly of chicoric acid and their biocompatibility studies. Supramol Chem 2011. [DOI: 10.1080/10610278.2011.601309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Evan M. Smoak
- a Department of Chemistry , Fordham University , 441 E. Fordham Road, Bronx, NY, 10458, USA
| | - Karl R. Fath
- b Department of Biology , Queens College, City University of New York and the Graduate Center , Kissena Boulevard, Flushing, NY, 11367, USA
| | - Stacey N. Barnaby
- a Department of Chemistry , Fordham University , 441 E. Fordham Road, Bronx, NY, 10458, USA
| | - Valerie C. Grant
- a Department of Chemistry , Fordham University , 441 E. Fordham Road, Bronx, NY, 10458, USA
| | - Ipsita A. Banerjee
- a Department of Chemistry , Fordham University , 441 E. Fordham Road, Bronx, NY, 10458, USA
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31
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Fighting bacterial infections—Future treatment options. Drug Resist Updat 2011; 14:125-39. [DOI: 10.1016/j.drup.2011.02.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 12/13/2022]
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32
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Šilhár P, Alakurtti S, Čapková K, Xiaochuan F, Shoemaker CB, Yli-Kauhaluoma J, Janda KD. Synthesis and evaluation of library of betulin derivatives against the botulinum neurotoxin A protease. Bioorg Med Chem Lett 2011; 21:2229-31. [PMID: 21421315 DOI: 10.1016/j.bmcl.2011.02.115] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 02/25/2011] [Accepted: 02/28/2011] [Indexed: 10/18/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic proteins currently known. Current treatments for botulinum poisoning are all protein based with a limited window of opportunity. Inhibition of the BoNT light chain protease (LC) has emerged as a new therapeutic strategy for the treatment of botulism as it may provide an effective post-exposure remedy. As such, a small library of 40 betulin derivatives was synthesized and screened against the light chain of BoNT serotype A (LC/A); five positive hits (IC(50) <100 μM) were uncovered. Detailed evaluation of inhibition mechanism of three most active compounds revealed a competitive model, with sub-micromolar K(i) value for the best inhibitor (7). Unfortunately, an in vitro cell-based assay did not show any protection of rat cerebellar neurons against BoNT/A intoxication by 7.
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Affiliation(s)
- Peter Šilhár
- Department of Chemistry, Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037, USA
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33
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Saunders MJ, Edwards BS, Zhu J, Sklar LA, Graves SW. Microsphere-based flow cytometry protease assays for use in protease activity detection and high-throughput screening. ACTA ACUST UNITED AC 2011; Chapter 13:Unit 13.12.1-17. [PMID: 20938917 DOI: 10.1002/0471142956.cy1312s54] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This protocol describes microsphere-based protease assays for use in flow cytometry and high-throughput screening. This platform measures a loss of fluorescence from the surface of a microsphere due to the cleavage of an attached fluorescent protease substrate by a suitable protease enzyme. The assay format can be adapted to any site or protein-specific protease of interest and results can be measured in both real time and as endpoint fluorescence assays on a flow cytometer. Endpoint assays are easily adapted to microplate format for flow cytometry high-throughput analysis and inhibitor screening.
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Affiliation(s)
- Matthew J Saunders
- Department of Chemical and Nuclear Engineering, University of New Mexico, Center for Biomedical Engineering, Albuquerque, New Mexico, USA
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34
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Salzameda NT, Eubanks LM, Zakhari JS, Tsuchikama K, DeNunzio NJ, Allen KN, Hixon MS, Janda KD. A cross-over inhibitor of the botulinum neurotoxin light chain B: a natural product implicating an exosite mechanism of action. Chem Commun (Camb) 2011; 47:1713-5. [PMID: 21203627 DOI: 10.1039/c0cc04078a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Clostridium botulinum produces the most lethal toxins known to man, as such they are high risk terrorist threats, and alarmingly there is no approved therapeutic. We report the first cross-over small molecule inhibitor of these neurotoxins and propose a mechanism by which it may impart its inhibitory activity.
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Affiliation(s)
- Nicholas T Salzameda
- Department of Chemistry, 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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35
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Li B, Peet NP, Butler MM, Burnett JC, Moir DT, Bowlin TL. Small molecule inhibitors as countermeasures for botulinum neurotoxin intoxication. Molecules 2010; 16:202-20. [PMID: 21193845 PMCID: PMC6259422 DOI: 10.3390/molecules16010202] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 12/20/2010] [Accepted: 12/29/2010] [Indexed: 11/18/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most potent of known toxins and are listed as category A biothreat agents by the U.S. CDC. The BoNT-mediated proteolysis of SNARE proteins inhibits the exocytosis of acetylcholine into neuromuscular junctions, leading to life-threatening flaccid paralysis. Currently, the only therapy for BoNT intoxication (which results in the disease state botulism) includes experimental preventative antibodies and long-term supportive care. Therefore, there is an urgent need to identify and develop inhibitors that will serve as both prophylactic agents and post-exposure ‘rescue’ therapeutics. This review focuses on recent progress to discover and develop small molecule inhibitors as therapeutic countermeasures for BoNT intoxication.
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Affiliation(s)
- Bing Li
- Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-508-757-2800; Fax: +1-508-757-1999
| | - Norton P. Peet
- Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA
| | | | - James C. Burnett
- Target, Structure-Based Drug Discovery Group, SAIC-Frederick, Inc., National Cancer Institute at Frederick, 1050 Boyles Street, Frederick, MD 21702, USA; E-Mail: (J.C.B.)
| | - Donald T. Moir
- Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA
| | - Terry L. Bowlin
- Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA
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36
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Eubanks LM, Šilhár P, Salzameda NT, Zakhari JS, Xiaochuan F, Barbieri JT, Shoemaker CB, Hixon MS, Janda KD. Identification of a Natural Product Antagonist against the Botulinum Neurotoxin Light Chain Protease. ACS Med Chem Lett 2010; 1:268-272. [PMID: 20959871 DOI: 10.1021/ml100074s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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. BoNTs are the most lethal known poisons affecting humans and has been recognized as a potential bioterrorist threat. Current treatments for botulinum poisoning are predominately prophylactic in nature relying on passive immunization with antitoxins. Inhibition of the BoNT light chain metalloprotease (LC) has emerged as a new therapeutic strategy for the treatment of botulism that may provide an effective post-exposure remedy. A high-throughput screening effort against the light chain of BoNT serotype A (LC/A) was conducted with the John Hopkins Clinical Compound Library comprised of over 1,500 existing drugs. Lomofungin, a natural product first isolated in the late 1960's, was identified as an inhibitor of LC/A, displaying classical noncompetitive inhibition kinetics with a K(i) of 6.7 ± 0.7 µM. Inhibitor combination studies reveal that lomofungin binding is nonmutually exclusive (synergistic). The inhibition profile of lomofungin has been delineated by the use of both an active site inhibitor, 2,4-dichlorocinnamic hydroxamate, and a noncompetitive inhibitor d-chicoric acid; the mechanistic implications of these observations are discussed. Lastly, cellular efficacy was investigated using a rat primary cell model which demonstrated that lomofungin can protect against SNAP-25 cleavage, the intracellular protein target of LC/A.
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Affiliation(s)
- Lisa M. Eubanks
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
| | - Peter Šilhár
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
| | | | - Joseph S. Zakhari
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
| | - Feng Xiaochuan
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, Massachusetts 01536
| | - Joseph T. Barbieri
- Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226
| | - Charles B. Shoemaker
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, Massachusetts 01536
| | - Mark S. Hixon
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
| | - Kim D. Janda
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
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37
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Lebeda FJ, Cer RZ, Mudunuri U, Stephens R, Singh BR, Adler M. The zinc-dependent protease activity of the botulinum neurotoxins. Toxins (Basel) 2010; 2:978-97. [PMID: 22069621 PMCID: PMC3153231 DOI: 10.3390/toxins2050978] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 04/30/2010] [Accepted: 05/05/2010] [Indexed: 12/11/2022] Open
Abstract
The botulinum neurotoxins (BoNT, serotypes A-G) are some of the most toxic proteins known and are the causative agents of botulism. Following exposure, the neurotoxin binds and enters peripheral cholinergic nerve endings and specifically and selectively cleaves one or more SNARE proteins to produce flaccid paralysis. This review centers on the kinetics of the Zn-dependent proteolytic activities of these neurotoxins, and briefly describes inhibitors, activators and factors underlying persistence of toxin action. Some of the structural, enzymatic and inhibitor data that are discussed here are available at the botulinum neurotoxin resource, BotDB (http://botdb.abcc.ncifcrf.gov).
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Affiliation(s)
- Frank J. Lebeda
- US Army Medical Research and Materiel Command, Ft. Detrick, MD 21702-5012, USA
| | - Regina Z. Cer
- Bioinformatics Support Group, Advanced Biomedical Computing Center, Information Systems Program, SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702, USA; (R.Z.C.); (U.M.); (R.S.)
| | - Uma Mudunuri
- Bioinformatics Support Group, Advanced Biomedical Computing Center, Information Systems Program, SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702, USA; (R.Z.C.); (U.M.); (R.S.)
| | - Robert Stephens
- Bioinformatics Support Group, Advanced Biomedical Computing Center, Information Systems Program, SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702, USA; (R.Z.C.); (U.M.); (R.S.)
| | - Bal Ram Singh
- Botulinum Research Center, University of Massachusetts Dartmouth, 285 Old Westport Road, Dartmouth, MA 02747, USA; (B.R.S.)
| | - Michael Adler
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA; (M.A.)
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