351
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Bedford CD, Miura M, Bottaro JC, Howd RA, Nolen HW. Nonquaternary cholinesterase reactivators. 4. Dialkylaminoalkyl thioesters of alpha-keto thiohydroximic acids as reactivators of ethyl methylphosphonyl- and 1,2,2-trimethylpropyl methylphosphonyl-acetylcholinesterase in vitro. J Med Chem 1986; 29:1689-96. [PMID: 3746817 DOI: 10.1021/jm00159a021] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In the search for improved lipophilic centrally active acetylcholinesterase (AChE) antidotes, a series of alpha-keto thiohydroximates were prepared and evaluated for their ability to reactivate AChEs inhibited by ethyl p-nitrophenyl methylphosphonate (EPMP) and soman (GD). The compounds conformed to the general structure 4-RC6H5C-(O)C(NOH)S(CH2)nN+R'R''.X- where R = H, CH3, F, Br, Cl, OCH3, CN;R' = CH3, C2H5, i-C3H7; R'' = H, CH3; X = Cl, I; and n = 2, 3. In this series, varying R substituents on the aryl ring produced compounds with oxime pKa values from 6.8 to 8.0, optimum for an AChE reactivator. Increasing lipophilicity of the amine segment correlated with reactivator potency, as did electron-withdrawing groups on the aryl moiety, presumably due to increased binding to hydrophobic sites surrounding the AChE active site. The in vitro reactivation potency of the alpha-keto thiohydroximates approaches and even surpasses that of 2-PAM and toxogonin for GD-inhibited AChE. These initial findings point to additional structure-activity relationships to assist in the design of improved antidotal compounds.
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352
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Golenda CF, Wirtz RA, Andre RG, Roberts DR. An insect bioassay as a primary screen for nerve agent antidotes. Mil Med 1986; 151:258-63. [PMID: 3086771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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353
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Puu G, Artursson E, Bucht G. Reactivation of nerve agent inhibited human acetylcholinesterases by HI-6 and obidoxime. Biochem Pharmacol 1986; 35:1505-10. [PMID: 3518721 DOI: 10.1016/0006-2952(86)90116-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Acetylcholinesterase was purified from human caudate nucleus and skeletal muscle. The enzyme preparations were used to study aging and reactivation by HI-6 and obidoxime after inhibition by soman and its isomers. HI-6 was found to be the most potent reactivator. For both enzyme preparations a higher reactivatability and a higher rate of aging were observed after inhibition by C+-soman than after inhibition by C(-)-soman. Aging was retarded by propidium diiodide. Reactivation by the two oximes was also studied after inhibition by tabun, sarin and VX. Tissue homogenates were used for this part of the work. Our conclusion is that HI-6 is superior to obidoxime for human acetylcholinesterases inhibited by soman and sarin, while obidoxime is better towards tabun-inhibited enzyme.
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354
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Kugusheva LI, Rozengart VI. [Interaction of membrane-bound and solubilized acetylcholinesterase from human and bovine erythrocytes with organophosphorus inhibitors]. UKRAINSKII BIOKHIMICHESKII ZHURNAL (1978) 1986; 58:13-8. [PMID: 3727030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Differences are found between the membrane-bound and soluble acetylcholinesterases of human and bovine erythrocytes when the enzyme interacts with organophosphoric inhibitors in the presence of acetylc choline and galantamine, a reverse inhibitor of acetylcholinesterase. In most cases prevention of inhibition of the soluble enzyme activity necessitates a higher (2-3 times higher) concentration of the protecting agent than protection of the membrane-bound enzyme. Concentrations of acetylcholine and galantamine providing a 50% protection of the enzyme did not practically depend on the strength of the anticholinesterase action of organophosphoric inhibitors.
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355
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Su CT, Wang PH, Liu RF, Shih JH, Ma C, Lin CH, Liu CY, Wu MT. Kinetic studies and structure-activity relationships of bispyridinium oximes as reactivators of acetylcholinesterase inhibited by organophosphorus compounds. FUNDAMENTAL AND APPLIED TOXICOLOGY : OFFICIAL JOURNAL OF THE SOCIETY OF TOXICOLOGY 1986; 6:506-14. [PMID: 3699334 DOI: 10.1016/0272-0590(86)90224-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The kinetics of the reactivation of acetylcholinesterase inhibited by isopropyl methylphosphonofluoridate was studied. The reactivators used include nine bispyridinium monooximes and three bispyridinium dioximes. The dissociation constant (Kd) and the rate constant (k2) of dephosphorylation of the complex formed from the organophosphorus acetylcholinesterase (OP-AChE) and the oxime were measured. The reactivation parameters obtained from the in vitro kinetic studies were used to elucidate the structure-activity relationships. The hydrophobic property of a nonoxime substituent at the 3-position on the pyridinium ring can exert a positive effect on their binding affinity to OP-AChE. However, the rate constants (k2) of the nucleophilic displacement of OP-AChE by oximes depend negatively on these physical and structural factors of the oximes. The correlations of the in vivo antidotal efficacy (ED50) of these bispyridinium oximes have been analyzed with their pharmacological properties, e.g., reactivation potency, antimuscarinic activities, and antinicotinic activities. However, no satisfactory correlations were observed. It may be concluded that the detoxication mechanism of poisoning by isopropyl methylphosphonofluoridate is different from those of pinacolyl methylphosphonofluoridate and paraoxon.
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356
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Sket D, Brzin M. Effect of HI-6, applied into the cerebral ventricles, on the inhibition of brain acetylcholinesterase by soman in rats. Neuropharmacology 1986; 25:103-7. [PMID: 3951676 DOI: 10.1016/0028-3908(86)90065-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
When applied to rats (intraperitoneally) immediately after subcutaneous injection of soman (120 micrograms/kg) HI-6 (100 mg/kg) protected about 40% of the activity of acetylcholinesterase (AChE) in the motor end plate region of the diaphragm but did not protect AChE in the brain. However, a partial protection of AChE in brain against inhibition by soman was obtained in anaesthetized, atropinized rats by the oxime injected into the cerebral ventricle 5 min before parenteral exposure to soman. The AChE activity in brain of rats pretreated with HI-6, analyzed 60 min after the injection of soman was between 10 and 19%, while that in non-protected animals did not exceed 1% of the control. The degree of protection of AChE in brain was dose-dependent. Large doses of HI-6 (greater than or equal to 100 micrograms) were tolerated by animals because of the pentobarbital anaesthesia which counteracted the lethal action of HI-6. The rate of "aging" of AChE in brain inhibited by soman was analyzed by intracerebroventricular injection of 200 micrograms of HI-6 at different time intervals after the subcutaneous injection of soman. A statistically-significant reactivation of inhibited AChE activity in brain was demonstrated when HI-6 was applied up to 20 min after soman. The protection and reactivation by HI-6 of both AChE in brain and AChE in muscle end plates in poisoning with soman appear to be quite similar.
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357
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Kenley RA, Bedford CD, Howd RA, Jackson SE. Reactivation of ethyl methylphosphonylated eel acetylcholinesterase in vitro by 2PAM, H16, and a series of nonquaternary alpha-ketothiohydroximates. Biochem Pharmacol 1985; 34:3606-8. [PMID: 4052103 DOI: 10.1016/0006-2952(85)90743-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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358
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Liu W, Zhao KY, Tsou CL. Reactivation kinetics of diethylphosphoryl acetylcholine esterase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 151:525-9. [PMID: 4029145 DOI: 10.1111/j.1432-1033.1985.tb09134.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The kinetics of reactivation of diethylphosphorylated acetylcholine esterase by pyridine-2-aldoxime methochloride has been studied using the approach of following the course of the hydrolysis of acetylcholine during the reactivation of the phosphorylated enzyme by the reactivator [Tsou, C.-L. (1965) Acta Biochem. Biophys. Sin. 5, 398-417]. Equations are derived based on the scheme of the formation of a complex between the phosphorylated enzyme and the reactivator and the rate of dissociation of this complex is not necessarily faster than the dephosphorylation and regeneration of the active enzyme. The regenerated enzyme then reacts with the substrate through an acetyl-enzyme intermediate as generally depicted. The equation obtained for product formation during the course of reactivation contains two exponential terms and this is in accord with the experimentally observed biphasic reaction. By making the assumption that the dissociation of the phosphorylated enzyme-reactivator complex is much faster than the dephosphorylation reaction, the above equation can be simplified to a form containing only one exponential term. By following the course of the reactivation reaction with the conventional approach of taking aliquots and assaying for enzyme activity recovery, it would appear likely that one would miss the initial stage of this biphasic reaction.
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359
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de Jong LP, Kossen SP. Stereospecific reactivation of human brain and erythrocyte acetylcholinesterase inhibited by 1,2,2-trimethylpropyl methylphosphonofluoridate (soman). BIOCHIMICA ET BIOPHYSICA ACTA 1985; 830:345-8. [PMID: 4027255 DOI: 10.1016/0167-4838(85)90294-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Human erythrocyte and brain acetylcholinesterase are preferentially inhibited by the P(-)-isomers of C(+/-)P(+/-)-soman. The enzymes inhibited by the P(-)-isomers behave similarly with respect to oxime-induced reactivation and aging. HI-6 is the best reactivator for C(+)P(-)-soman-inhibited acetylcholinesterases. Oxime-induced reactivation of the C(-)P(-)-soman-inhibited acetylcholinesterases is much more difficult to achieve.
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360
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Galli A, Malmberg Aiello P, Renzi G, Bartolini A. In-vitro and in-vivo protection of acetylcholinesterase by eseroline against inactivation by diisopropyl fluorophosphate and carbamates. J Pharm Pharmacol 1985; 37:42-8. [PMID: 2858526 DOI: 10.1111/j.2042-7158.1985.tb04928.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The protective action of eseroline--(3aS,8aR)-1,2,3,3a,8,8a-hexahydro-1,3 a, 8-trimethyl-pyrrolo[2,3-b]indol-5-ol--salicylate against (DFP) diisopropyl fluorophosphate and carbamate poisoning of cholinesterases (ChEs) has been examined in-vitro with human erythrocytes and purified preparations of electric eel acetylcholinesterase (AChE) and of horse serum butyrylcholinesterase (BuChE), and in-vivo using mice. Eseroline afforded 50% protection (ED 50) of erythrocyte AChE against inactivation by 1 microM DFP, physostigmine or neostigmine, at concentrations of 4.3, 22 and 23.5 microM, respectively, while for eel AChE protection against 10 and 30 microM DFP, 0.3 and 1 microM physostigmine and 1 microM neostigmine the eseroline ED 50 values were 0.3, 0.4, 0.7, 1.9 and 5.6 microM, respectively. On the other hand, up to 0.3 mM eseroline did not appreciably affect the inhibitory action of the same drugs on horse serum BuChE. Eseroline concentrations in the range 0.1-1 mM were able to reactivate 20-42% of erythrocyte AChE previously inhibited by 100 microM physostigmine, but failed to reactivate the DFP (10 microM)-pretreated enzyme to any extent. Finally, eseroline salicylate injected into mice (10 mg kg-1 s.c.) protected an average of 82 and 26% of the animals against lethal doses of DFP (7 mg kg-1 s.c.) and physostigmine sulphate (1 mg kg-1 i.p.) respectively, which were administered 15 min later. These results indicate that the protective activity of eseroline correlates well with its own anti-ChE profile, and that the effectiveness of the protection depends largely on the rate of AChE inhibition by the agents used to inactivate the enzyme.
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361
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de Jong LP, Wolring GZ. Aging and stereospecific reactivation of mouse erythrocyte and brain acetylcholinesterases inhibited by soman. Biochem Pharmacol 1985; 34:142-5. [PMID: 3966915 DOI: 10.1016/0006-2952(85)90113-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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362
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Yamanaka S, Nishimura M. [Effects of organophosphorus compounds and PAM on cholinesterase activity in rat tissues]. Nihon Eiseigaku Zasshi 1984; 39:795-806. [PMID: 6533340 DOI: 10.1265/jjh.39.795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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363
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Stamenović BA. [Neurophysiologic study of the effect of 2PAM-Cl on the neuromuscular junction]. VOJNOSANIT PREGL 1984; 41:326-35. [PMID: 6516240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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364
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Cetković S, Cvetković M, Jandrić D, Cosić M, Bosković B. Effect of PAM-2 Cl, HI-6, and HGG-12 in poisoning by tabun and its thiocholine-like analog in the rat. Toxicol Sci 1984; 4:S116-23. [PMID: 6547103 DOI: 10.1093/toxsci/4.2part2.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has been shown that HI-6 was the most potent oxime so far known in poisoning by sarin, VX , and soman, but its protective effect in tabun poisoning, allegedly due to poor reactivation of inhibited ChE, was much less pronounced. We have found that the thiocholine-like analog of tabun , O-ethyl, N-N- dimethyamino -S-(2-diethylaminoethyl)- thiophosphatemethylsul fomethylate (Ta-S-N+), was very useful in resolving this problem and established the relationship between reactivating and protective effects of PAM-2 Cl, HI-6, and HGG-12 in rats. PAM-2 Cl (protective ratio (PR) = 22.1) and HI-6 (PR = 24.8), combined with atropine, were very effective against Ta-S-N+ poisoning and reactivating inhibited RBC AChE in vitro and rat blood ChE in vivo. The inefficiency of PAM-2 Cl (PR = 1.6) and HI-6 (PR = 2) in tabun poisoning was due to their inadequacy to reactive tabun -inhibited ChEs . The protective effects of HGG-12 in tabun (PR = 2.8) and Ta-S-N+ poisoning (PR = 2.6) were low, and in the absence of any reactivation of inhibited ChEs , have been attributed to its direct pharmacological effects, which were much more potent in the comparison with PAM-2 Cl or HI-6. It is concluded that the reactivation of inhibited ChE is of decisive importance in the efficient protection in poisoning by tabun and other known chemical warfare nerve agents, whereas their direct pharmacological effects are of limited value, allowing survival of animals only against a few LD50s .
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365
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Bosković B, Kovacević V, Jovanović D. PAM-2 Cl, HI-6, and HGG-12 in soman and tabun poisoning. FUNDAMENTAL AND APPLIED TOXICOLOGY : OFFICIAL JOURNAL OF THE SOCIETY OF TOXICOLOGY 1984; 4:S106-15. [PMID: 6724203 DOI: 10.1093/toxsci/4.2part2.106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Acute sc toxicity of soman increased in the order, mice----rats----guinea pigs----dogs, being 12.6 times more toxic to dogs (LD50 = 0.05 mumol/kg) than to mice. It was 2.8 times more toxic than tabun to mice and 35 times more toxic to dogs. HI-6 was the least toxic and had similar toxicity values to the four animal species studied and HGG-12 the most toxic of the three oximes used. HGG-12 has shown the greatest interspecies variation (rats:dogs = 1:19.5). HI-6, HGG-12, and PAM-2 Cl (in conjunction with atropine and diazepam) revealed the best protective effect in soman-poisoned dogs, with the respective protective indices of 9, 6.3, and 3.5, followed by guinea pigs. In tabun poisoning the best, but relatively low, protective effect was found only in guinea pigs. The introduction of diazepam increased the protective effects of atropine-oxime combination in soman and tabun poisoning by 10 to 80%. We suggest that the high toxicity of soman and low toxicity of HI-6 may be anticipated in man. The inefficiency of HI-6, HGG-12, and PAM-2 Cl in tabun poisoning points either to the search of new compounds or to the use of the mixture of the oximes found to be effective against the known chemical warfare nerve agents.
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366
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Glickman AH, Wing KD, Casida JE. Profenofos insecticide bioactivation in relation to antidote action and the stereospecificity of acetylcholinesterase inhibition, reactivation, and aging. Toxicol Appl Pharmacol 1984; 73:16-22. [PMID: 6710513 DOI: 10.1016/0041-008x(84)90047-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Poisoning signs in chicks administered the organophosphorus insecticide profenofos correlated with in vivo inhibition of brain acetylcholinesterase (AChE) activity. Mixtures of atropine with eserine, pyridinium oximes, or the bispyridinium compound SAD-128 increased the LD50 of coadministered profenofos by up to sevenfold in chicks and fourfold in mice. Atropine and the oximes were less effective as profenofos antidotes, indicating that profenofos-inhibited AChE may undergo rapid aging. Brain AChE from chicks poisoned with profenofos was not reactivated by pralidoxime methanesulfonate, although it was from chicks poisoned with the phosphoramidothiolate, methamidophos. Similarly, eel AChE, inhibited in vitro by bioactivated (-)-profenofos, the most toxic isomer, did not reactivate in contrast to that inhibited by methamidophos, nonbioactivated (-)-profenofos, and (+)-profenofos, with or without bioactivation. It appears that the action of eserine and possibly SAD-128 was due to protecting AChE or cholinergic receptors from profenofos or bioactivated profenofos and that oximes may work in the same way rather than as reactivators due to rapid aging of the inhibited AChE.
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367
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Matsubara T, Horikoshi I. Chemical reactivations of inactivated acetylcholinesterase after 2-PAM therapy in fenitrothion-poisoned rat and rabbit. JOURNAL OF PHARMACOBIO-DYNAMICS 1984; 7:131-7. [PMID: 6726618 DOI: 10.1248/bpb1978.7.131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We investigated the reactivation of inactivated acetylcholinesterase (AChE) after 2-PAM therapy in acute fenitrothion poisonings of two species of rat and rabbit. By single treatment with 2-PAM carried out immediately after fenitrothion administration, the significant reactivations of inactivated AChE in red blood cell (RBC) and brain as well as inactivated cholinesterase (ChE) in plasma were observed at 2 h after administration of 20 mg/kg fenitrothion in rat, while these reactivations became less in rats severely poisoned with 500 mg/kg fenitrothion. Although these significant reactivations disappeared 6 h after the single treatment with 2-PAM, the repeated treatments with 2-PAM induced the prolongation of the reactivations of inactivated AChEs and ChE. These results suggest that 2-PAM would be more effective to light poisoning with fenitrothion, and that the repetition of 2-PAM treatment would be very important to obtain the sufficient antidotal actions. In rabbits as well as rats, the considerable reactivations of inactivated AChEs in RBC and brain and inactivated ChE in plasma were observed by the single treatment with 2-PAM in fenitrothion poisoning. These reactivations in brain AChE indicate that 2-PAM can penetrate the blood brain barrier of both rat and rabbit, despite its quaternary character.
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368
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Benschop HP, Konings CA, Van Genderen J, De Jong LP. Isolation, anticholinesterase properties, and acute toxicity in mice of the four stereoisomers of the nerve agent soman. Toxicol Appl Pharmacol 1984; 72:61-74. [PMID: 6710485 DOI: 10.1016/0041-008x(84)90249-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The four stereoisomers of the nerve agent pinacolyl methylphosphonofluoridate (soman), designated as C(+)P(+), C(+)P(-), C(-)P(+), and C(-)P(-), have different toxicologic properties due to stereospecific interactions in living organisms. We report the isolation of these stereoisomers with more than 99% optical purity. This result was realized by means of (i) complete optical resolution of pinacolyl alcohol, (ii) synthesis of C(+)- and C(-)-soman from the (+)- and (-)-enantiomers of the alcohol, (iii) optimalization of conditions for stereospecific inhibition of alpha-chymotrypsin with the P(-)-isomers of C(+)- and C(-)-soman, followed by isolation of the C(+)P(+)- and C(-)P(+)-isomers, (iv) isolation of the C(+)P(-)- and C(-)P(-)-isomers after incubation of C(+)- and C(-)-soman, respectively, in rabbit plasma, which hydrolyzes stereospecifically the P(+)-isomers. The bimolecular rate constants for inhibition of electric eel acetylcholinesterase (AChE) at pH 7.7, 25 degrees C, are at least 3.6 X 10(4) larger for the P(-)- than for the P(+)-isomers. The enzyme inhibited with C(+)P(-)-soman is much more effectively reactivated with the oximes HI-6, HGG-42, and obidoxime than AChE inhibited with C(-)P(-)-soman. The LD50 values (sc, mice) are in accordance with the P(-)/P(+) ratio of inhibition rates of AChE, i.e. 99, 38, greater than 5000, greater than 2000, 214, 133, and 156 micrograms/kg for C(+)P(-)-, C(-)P(-)-, C(+)P(+)-, C(-)P(+)-, C(+)-, C(-)-soman, and "soman", respectively. The relative LD50 values of the C(-)P(-)- and C(+)P(-)-isomers do not correspond with the small differences in their rates of inhibition of AChE, indicating that such small rate ratios may be overruled by other stereospecific effects, e.g., in vivo rates of detoxification.
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369
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Doebler JA, Bocan TM, Moore RA, Shih TM, Anthony A. Brain neuronal RNA metabolism during acute soman toxication: effects of antidotal pretreatments. Neurochem Res 1983; 8:997-1011. [PMID: 6194444 DOI: 10.1007/bf00965196] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Effects of various antidotal treatments on neuronal RNA contents and on soman induced RNA and acetylcholinesterase (AChE) depletion were monitored using quantitative cytochemical techniques. In rats only with antidotes, atropine depressed whereas pralidoxime (2-PAM) elevated RNA contents of both caudate and cerebrocortical (Layer V) neurons. Soman produced a virtually complete inhibition of AChE activity and a moderate decline in neuronal RNA contents. Atropine pretreatment partially restored neuronal RNA levels. Atropine + 2-PAM prophylaxis eventuated in a complete restoration of RNA levels but no reactivation of AChE. Addition of physostigmine to the atropine + 2-PAM treatment regimen resulted in appreciable AChE reactivation but reduced RNA levels. The overall data indicate that: (1) soman-induced neuronal RNA depletion can be completely reversed by antidotal pretreatments; (2) no precise relationship exists between the extents of antidote-induced restoration of RNA and AChE levels; and (3) 2-PAM exerts marked effects on the brain neuronal network which are unrelated to AChE reactivation. It is postulated that effects of soman and antidotes on neuronal RNA metabolism may signify alterations in acetylcholine (ACh) sensitivity and that pharmacologic manipulation of ACh responsiveness during organophosphate cholinesterase poisoning may be a mechanism for additional therapeutic intervention.
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370
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Schoene K, Steinhanses J, Oldiges H. Reactivation of soman inhibited acetylcholinesterase in vitro and protection against soman in vivo by bispyridinium-2-aldoximes. Biochem Pharmacol 1983; 32:1649-51. [PMID: 6860352 DOI: 10.1016/0006-2952(83)90343-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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371
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Van Helden HP, Wolthuis OL. Evidence for an intramuscular depot of the cholinesterase inhibitor soman in the rat. Eur J Pharmacol 1983; 89:271-4. [PMID: 6307710 DOI: 10.1016/0014-2999(83)90504-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Isolated rat diaphragms were treated with the oxime HI-6, 25 min after the start of soman exposure for 5, 15, 20 or 25 min. Recovery of neuromuscular transmission (NMT) was smaller and the subsequent spontaneous failure of NMT greater when soman exposure was longer. Diaphragms taken from anaesthetized atropinized soman-poisoned rats treated with HI-6 again showed spontaneous failure of NMT when tested repeatedly in vitro. In vivo pretreatment with a soman simulator prevented reinhibition in vitro. The results are indicative of a simulator-sensitive soman depot in muscles.
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372
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Kitchen I, Green PG. Differential effects of di-isopropylfluorophosphate poisoning and its treatment on opioid antinociception in the mouse. Life Sci 1983; 33 Suppl 1:669-72. [PMID: 6664242 DOI: 10.1016/0024-3205(83)90591-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Compounds which enhance cholinergic activity have been reported to interact with opioid drugs. We have shown, using the hot-plate test in mice that di-isopropylfluorophosphate potentiates the antinociceptive activity of alfentanil but has no effect on the activity of morphine or fentanyl. Administration of atropine and pralidoxime as a treatment for DFP poisoning does not reverse this effect, and itself potentiates morphine antinociception. The results suggest that a cholinergic/opioid interaction is dependent on the opioid studied, and may have clinical importance when opioid drugs are required in patients poisoned by irreversible anticholinesterases.
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373
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Harris LW, Stitcher DL. Reactivation of VX-inhibited cholinesterase by 2-PAM and HS-6 in rats. Drug Chem Toxicol 1983; 6:235-40. [PMID: 6628257 DOI: 10.3109/01480548309017814] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Atropinized rats intoxicated with ethyl-S-2-diisopropyl aminoethyl methyl phosphonothioate (VX), 15 mg/kg iv, were divided into three groups and were treated with normal saline, iv, 30 mg/kg of 2-PAM C1, iv, and 30 mg/kg of HS-6, iv. One hr after administration of therapy they were decapitated and cholinesterase (ChE) activity was determined on blood, brain and diaphragm tissue. Both 2-PAM C1 and HS-6 markedly reactivated VX-inhibited blood and diaphragm ChE. Brain ChE activity was not significantly reactivated by either oxime. The effectiveness of these oximes in restoration of VX-inactivated ChE in vivo offers an explanation as to why conventional atropine/oxime therapy is so effective against VX intoxication.
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374
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Mager PP, Das Gupta S. Quantitative structure-activity relationships of reactivators of phosphylated acetylcholinesterase. Part 2. DIE PHARMAZIE 1982; 37:607-8. [PMID: 7146070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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375
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Trinus FP, Braver-Chernobul'skaia BS, Luĭk AI. [Noncholinesterase component in the molecular mechanism of action of the cholinesterase reactivator dipyroxime]. BIULLETEN' EKSPERIMENTAL'NOI BIOLOGII I MEDITSINY 1982; 93:66-8. [PMID: 7115940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
While changing the structure of the superficial layers of the serum albumin molecule, the cholinesterase reactivator dipyroxime increases the protein binding capacity as regards the organophosphorus poison dimethyldichlorovinyl phosphate. This may be conductive to the reduction of the latter's acute toxicity.
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