Our proposed project is directed to improving prophylaxis and therapy for organophosphate nerve agent organophosphate exposure through the design of mutant human acetylcholinesterases (AChEs), novel oximes and related reactivating nucleophiles. This strategy of """"""""oxime-assisted catalysis"""""""" modifies AChE such that, when placed in the circulation, the oxime and AChE become a catalytic, rather than a stoichiometric, scavenger of organophosphates. Proof of principle has already been established for hydrolysis of a series of organophosphates, and we will refine AChE mutations and oxime structure to enhance catalytic rates for hydrolysis and retention in plasma space. Since oxime therapy, 2-PAM and HI-6, also reactivates inhibited AChE at the target site and the therapeutic benefits of long term oxime therapy have become fully appreciated recently, we propose to design new reactivators based on contemporary knowledge of AChE structure to which we and other groups have contributed to over the past two decades. This approach considers impaction of the active center gorge and angle of access of the oxime as limiting constraints in the design strategy. Moreover, the UCSD and TSRI groups have applied a novel freeze-frame, click chemistry to the development of reactivating agents using AChE-phosphonate conjugates as the template for synthesis of the triazoles. In addition to oxime assisted catalysis in plasma, new oximes and other nucleophiles will be developed as novel reactivating agents at the target site. This chemistry also enjoys the advantage of combinatorial screening for medium to high throughput in the synthesis-screening paradigm. Nucleophiles and nucleophile AChE combinations will be optimized for enhancing therapeutic efficacy to the particular offending organophosphate. Hence, our approach will both augment catalytic scavenging of organophosphates in the circulation and enhance reactivation at the target tissues.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project--Cooperative Agreements (U01)
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Special Emphasis Panel (ZNS1-SRB-R (22))
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Jett, David A
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University of California San Diego
Schools of Medicine
La Jolla
United States
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Rosenberg, Yvonne J; Wang, Jerry; Ooms, Tara et al. (2018) Post-exposure treatment with the oxime RS194B rapidly reactivates and reverses advanced symptoms of lethal inhaled paraoxon in macaques. Toxicol Lett 293:229-234
Rosenberg, Yvonne J; Mao, Lingjun; Jiang, Xiaoming et al. (2017) Post-exposure treatment with the oxime RS194B rapidly reverses early and advanced symptoms in macaques exposed to sarin vapor. Chem Biol Interact 274:50-57
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Sit, Rakesh K; Fokin, Valery V; Amitai, Gabriel et al. (2014) Imidazole aldoximes effective in assisting butyrylcholinesterase catalysis of organophosphate detoxification. J Med Chem 57:1378-89
Radi?, Zoran; Dale, Trevor; Kovarik, Zrinka et al. (2013) Catalytic detoxification of nerve agent and pesticide organophosphates by butyrylcholinesterase assisted with non-pyridinium oximes. Biochem J 450:231-42
Morris, Garrett M; Green, Luke G; Radi?, Zoran et al. (2013) Automated docking with protein flexibility in the design of femtomolar ""click chemistry"" inhibitors of acetylcholinesterase. J Chem Inf Model 53:898-906
Kovarik, Zrinka; Macek, Nikolina; Sit, Rakesh K et al. (2013) Centrally acting oximes in reactivation of tabun-phosphoramidated AChE. Chem Biol Interact 203:77-80

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