Sit RK, Fokin VV, Amitai G, Sharpless KB, Taylor P, Radić Z. Imidazole aldoximes effective in assisting butyrylcholinesterase catalysis of organophosphate detoxification.
J Med Chem 2014;
57:1378-89. [PMID:
24571195 PMCID:
PMC4167068 DOI:
10.1021/jm401650z]
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Abstract
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Intoxication
by organophosphate (OP) nerve agents and pesticides
should be addressed by efficient, quickly deployable countermeasures
such as antidotes reactivating acetylcholinesterase or scavenging
the parent OP. We present here synthesis and initial in vitro characterization of 14 imidazole aldoximes and their structural
refinement into three efficient reactivators of human butyrylcholinesterase
(hBChE) inhibited covalently by nerve agent OPs, sarin, cyclosarin,
VX, and the OP pesticide metabolite, paraoxon. Rapid reactivation
of OP–hBChE conjugates by uncharged and nonprotonated tertiary
imidazole aldoximes allows the design of a new OP countermeasure by
conversion of hBChE from a stoichiometric to catalytic OP bioscavenger
with the prospect of oral bioavailability and central nervous system
penetration. The enhanced in vitro reactivation efficacy
determined for tertiary imidazole aldoximes compared to that of their
quaternary N-methyl imidazolium analogues is attributed
to ion pairing of the cationic imidazolium with Asp 70, altering a
reactive alignment of the aldoxime with the phosphorus in the OP–hBChE
conjugate.
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