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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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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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