title: Novel bifunctional hybrid small molecule scavengers for mitigating nerve agents toxicity.
abstract: The antidotal treatment of organophosphates (OP) nerve agents (NA) poisoning is based on anticholinergics (e.g. atropine) combined with oxime reactivators (e.g. 2PAM) of acetylcholinesterase (AChE). This treatment is symptomatic and does not degrade the OP. New small-molecule OP scavengers were developed as bifunctional hybrids. Their molecular design was based on combining a nucleophile that directly degrades OP with a moiety that reactivates OP-inhibited AChE. The OP degrading moiety is either benzhydroxamic acid (BHA) or 4-pyridinehydroxamic acid (4PHA) coupled via (CH2)n, (n = 1 or 3) to 2PAM. Three newly synthesized oxime-hydroxamate hybrids: 2PAMPr4PHA, 2PAMMeBHA and 2,4-DiPAMMeBHA were found to detoxify sarin, cyclosarin and soman in solution at 3-10-fold faster rate than 2PAM and to reactivate OP-AChE in vitro. 2PAMPr4PHA displayed 18-fold faster reactivation than 2-PAM of cyclosarin-inhibited HuAChE (kr= 3.6 × 102vs. 0.2 × 102M-1min-1, respectively, 37 °C). These hybrids inhibited AChE reversibly, IC50= 16-48 μM, thereby decreasing the inhibition rates by OPs. The LD50(im) of 2PAMPr4PHA, 2PAMMeBHA and 2,4DiPAMMeBHA are >568, 508 and >506 μmol/kg in rats and 144, 203 and >506 μmol/kg in guinea pigs. The rate of blood ChE recovery by the hybrids administered either pre- or post-exposure to 0.8xLD50sarin was comparable or faster than 2PAM. Antidotal efficacy of 2PAMPr4PHA, 2PAMMeBHA and 2,4DiPAMMeBHA administered with atropine, as pre-treatment to sarin in rats (im), yielded protection ratios (PR) 11.6, 11.5 and 4.7, respectively, vs. 5.5 with 2PAM. Post-treatment against various OPs in rats and guinea-pigs yielded PRs higher or similar to that of 2 PAM. Our in vivo data indicates that some hybrids may serve as efficient small molecule scavengers for mitigating the toxicity of OP NAs.
authors.affiliation: Department of Pharmacology, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: amitai.gabi36@gmail.com.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Amitai
authors.affiliation: Department of Pharmacology, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: rellieg@gmail.com.
authors.forename: Rellie
authors.initials: R
authors.lastname: Gez
authors.affiliation: Department of Pharmacology, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: raveh.lily@gmail.com.
authors.forename: Lily
authors.initials: L
authors.lastname: Raveh
authors.affiliation: Department of Organic Chemistry, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: nirab@iibr.gov.il.
authors.forename: Nira
authors.initials: N
authors.lastname: Bar-Ner
authors.affiliation: Department of Pharmacology, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: ettieg@iibr.gov.il.
authors.forename: Ettie
authors.initials: E
authors.lastname: Grauer
authors.affiliation: Department of Pharmacology, Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. Electronic address: shirac@iibr.gov.il.
authors.forename: Shira
authors.initials: S
authors.lastname: Chapman
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood / Q000378:metabolism; D000818:Animals; D000931:Antidotes / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D002801:Cholinesterase Reactivators / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D006877:Hydroxamic Acids / Q000737:chemistry; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008297:Male; D000067397:Nerve Agents / Q000633:toxicity*; D009498:Neurotoxins / Q000633:toxicity*; D010755:Organophosphates / Q000633:toxicity; D009943:Organophosphorus Compounds / Q000633:toxicity; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D010091:Oximes / Q000737:chemistry; D010766:Phosphorylation / Q000187:drug effects; D017207:Rats, Sprague-Dawley; D012524:Sarin / Q000506:poisoning; D054852:Small Molecule Libraries / Q000494:pharmacology*; D013997:Time Factors; D023382:Toxicity Tests, Acute
chemical_list: D000110:Acetylcholinesterase; D000931:Antidotes; D002800:Cholinesterase Inhibitors; D002801:Cholinesterase Reactivators; D006877:Hydroxamic Acids; D000067397:Nerve Agents; D009498:Neurotoxins; D010755:Organophosphates; D009943:Organophosphorus Compounds; D009946:Organothiophosphorus Compounds; D010091:Oximes; D012524:Sarin; D054852:Small Molecule Libraries; C009680:VX-agent; C053914:cyclohexyl methylphosphonofluoridate
keywords: 2-Pyridine aldoxime methyl chloride; 4-Pyridine hydroxamic acid; Acetylcholinesterase; Benzhydroxamic acid; Bifunctional; Cyclosarin; Detoxification; Guinea pig; Nerve agents; Organophosphates; Oxime; Rat; Sarin; Scavengers; Small molecule; Soman; VX