Casualties caused by organophosphorus pesticides are a burden for health systems in developing and poor countries. Such compounds are potent acetylcholinesterase irreversible inhibitors, and share the toxic profile with nerve agents. Pyridinium oximes are the only clinically available antidotes against poisoning by these substances, but their poor penetration into the blood-brain barrier hampers the efficient enzyme reactivation at the central nervous system. In searching for structural factors that may be explored in future SAR studies, we evaluated neutral aryloximes as reactivators for paraoxon-inhibited Electrophorus eel acetylcholinesterase. Our findings may result into lead compounds, useful for development of more active compounds for emergencies and supportive care.

Brazilian Army Institute of Chemical Biological Radiological and Nuclear Defense Avenida das Américas 28705 Rio de Janeiro 23020 470 Brazil

Castelo Branco University School of Pharmacy Avenida Santa Cruz 1631 Rio de Janeiro 21710 255 Brazil

Department of Chemistry Faculty of Science University of Hradec Králové Rokitanskeho 62 50003 Hradec Králové Czech Republic

Emergency and Rescue Department Praça São Salvador 4 Rio de Janeiro 22231 170 Brazil

Laboratory of Molecular Modelling Applied to Chemical and Biological Defense Praça General Tibúrcio 80 Rio de Janeiro 22290 270 Brazil

National Institute of Metrology Standardization and Industrial Quality Avenida Nossa Senhora das Graças 50 Duque de Caxias 25250 020 Brazil

School of Biomedicine University Universus Veritas Rua Marquês de Abrantes 55 Rio de Janeiro 22230 060 Brazil

Walter Mors Institute of Research on Natural Products CCS Bloco H Rio de Janeiro 21941 902 Brazil

See more in PubMed

Taylor P. The cholinesterases. [(accessed on 23 August 2019)];J. Biol. Chem. 1991 266:4025–4028. Available online: http://www.jbc.org/content/266/7/4025.long. PubMed

Taylor P., Radic Z. The Cholinesterases: From Genes to Proteins. Annu. Rev. Pharmacol. Toxicol. 1994;34:281–320. doi: 10.1146/annurev.pa.34.040194.001433. PubMed DOI

Soreq H., Seidman S. Acetylcholinesterase—New roles for an old actor. Nat. Rev. Neurosci. 2001;2:294–302. doi: 10.1038/35067589. PubMed DOI

Quinn D.M. Acetylcholinesterase: Enzyme structure, reaction dynamics, and virtual transition states. Chem. Rev. 1987;87:955–979. doi: 10.1021/cr00081a005. DOI

Chatonnet A., Lockridge O. Comparison of butyrylcholinesterase and acetylcholinesterase. Biochem. J. 1989;260:625–634. doi: 10.1042/bj2600625. PubMed DOI PMC

Sussman J.L., Silman I. Acetylcholinesterase: Structure and use as a model for specific cation—protein interactions. Curr. Opin. Struct. Boil. 1992;2:721–729. doi: 10.1016/0959-440X(92)90207-N. DOI

Dvir H., Silman I., Harel M., Rosenberry T.L., Sussman J.L. Acetylcholinesterase: From 3D Structure to Function. Chem. Interactions. 2010;187:10–22. doi: 10.1016/j.cbi.2010.01.042. PubMed DOI PMC

Eddleston M., Buckley N.A., Eyer P., Dawson A.H. Management of acute organophosphorus pesticide poisoning. Lancet. 2008;371:597–607. doi: 10.1016/S0140-6736(07)61202-1. PubMed DOI PMC

Costanzi S., Machado J.-H., Mitchell M. Nerve Agents: What They Are, How They Work, How to Counter Them. ACS Chem. Neurosci. 2018;9:873–885. doi: 10.1021/acschemneuro.8b00148. PubMed DOI

Organisation for the Prohibition of Chemical Weapons—OPCW Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction—CWC. [(accessed on 6 October 2019)];1997 Available online: www.opcw.org.

Bernardes M.F.F., Pazin M., Pereira L.C., Dorta D.J. Impact of Pesticides on Environmental and Human Health. [(accessed on 23 August 2019)]; Available online: https://www.intechopen.com/books/toxicology-studies-cells-drugs-and-environment/impact-of-pesticides-on-environmental-and-human-health.

Pimentel D. ‘Environmental and Economic Costs of the Application of Pesticides Primarily in the United States’. Environ. Dev. Sustain. 2005;7:229–252. doi: 10.1007/s10668-005-7314-2. DOI

Ecobichon D.J. Pesticide use in developing countries. Toxicology. 2001;160:27–33. doi: 10.1016/S0300-483X(00)00452-2. PubMed DOI

Atreya K., Sitaula B.K., Johnsen F.H., Bajracharya R.S. Continuing Issues in the Limitations of Pesticide Use in Developing Countries. J. Agric. Environ. Ethics. 2011;24:49–62. doi: 10.1007/s10806-010-9243-9. DOI

The Guardian “Hundreds of new pesticides approved in Brazil under Bolsonaro”. [(accessed on 23 August 2019)]; Available online: https://www.theguardian.com/environment/2019/jun/12/hundreds-new-pesticides-approved-brazil-under-bolsonaro.

Reuters “Brazil approves rules for pesticides easing toxicity criteria”. [(accessed on 23 August 2019)]; Available online: https://www.reuters.com/article/us-brazil-pesticides/brazil-approves-rules-for-pesticides-easing-toxicity-criteria-idUSKCN1UI2JJ.

Pignati W.A., Lima F.A.N.S., Lara S.S., Correa M.L.M., Barbosa J.R., Leão L.H.C., Pignatti M.G. Spatial distribution of pesticide use in Brazil: A strategy for Health Surveillance. Ciência Saúde Coletiva. 2017;22:3281–3293. doi: 10.1590/1413-812320172210.17742017. PubMed DOI

Dasgupta S., Mamingi N., Meisner C. Pesticide use in Brazil in the era of agroindustrialization and globalization. Environ. Dev. Econ. 2001;6:459–482. doi: 10.1017/S1355770X01000262. DOI

Nicolopoulou-Stamati P., Maipas S., Kotampasi C., Stamatis P., Hens L. Chemical Pesticides and Human Health: The Urgent Need for a New Concept in Agriculture. Front. Public Heal. 2016;4:231. doi: 10.3389/fpubh.2016.00148. PubMed DOI PMC

Eddleston M., Karalliedde L., Buckley N., Fernando R., Hutchinson G., Isbister G., Konradsen F., Murray D., Piola J.C., Senanayake N., et al. Pesticide poisoning in the developing world—A minimum pesticides list. Lancet. 2002;360:1163–1167. doi: 10.1016/S0140-6736(02)11204-9. PubMed DOI

Piccoli C., Cremonese C., Koifman R., Koifman S., Freire C. Occupational exposure to pesticides and hematological alterations: A survey of farm residents in the South of Brazil. Ciência Saúde Coletiva. 2019;24:2325–2340. doi: 10.1590/1413-81232018246.13142017. PubMed DOI

Bardin P.G., van Eeden S.F., Moolman J.A., Foden A.P., Joubert J.R. Organophosphate and Carbamate Poisoning. Arch. Intern. Med. 1994;154:1433–1441. doi: 10.1001/archinte.1994.00420130020005. PubMed DOI

Steenland K. Chronic neurological effects of organophosphate pesticides. BMJ. 1996;312:1312–1313. doi: 10.1136/bmj.312.7042.1312. PubMed DOI PMC

Eskenazi B., Bradman A., Castorina R. Exposures of children to organophosphate pesticides and their potential adverse health effects. Environ. Heal. Perspect. 1999;107:409–419. doi: 10.1289/ehp.99107s3409. PubMed DOI PMC

Kofman O., Berger A., Massarwa A., Friedman A., Abu Jaffar A. Motor Inhibition and Learning Impairments in School-Aged Children Following Exposure to Organophosphate Pesticides in Infancy. Pediatr. Res. 2006;60:88–92. doi: 10.1203/01.pdr.0000219467.47013.35. PubMed DOI

Pasiani J.O., Torres P., Silva J.R., Diniz B.Z., Caldas E.D. Knowledge, Attitudes, Practices and Biomonitoring of Farmers and Residents Exposed to Pesticides in Brazil. Int. J. Environ. Res. Public Health. 2012;9:3051–3068. doi: 10.3390/ijerph9093051. PubMed DOI PMC

Rastogi S.K., Tripathi S., Ravishanker D. A study of neurologic symptoms on exposure to organophosphate pesticides in the children of agricultural workers. Indian J. Occup. Environ. Med. 2010;14:54–57. doi: 10.4103/0019-5278.72242. PubMed DOI PMC

Mercey G., Verdelet T., Renou J., Kliachyna M., Baati R., Nachon F., Jean L., Renard P.-Y. Reactivators of Acetylcholinesterase Inhibited by Organophosphorus Nerve Agents. Accounts Chem. Res. 2012;45:756–766. doi: 10.1021/ar2002864. PubMed DOI

Litchfield M.H. Estimates of acute pesticide poisoning in agricultural workers in less developed countries. Toxicol. Rev. 2005;24:271–278. doi: 10.2165/00139709-200524040-00006. PubMed DOI

Benelli G., Jeffries C.L., Walker T. Biological Control of Mosquito Vectors: Past, Present, and Future. Insects. 2016;7:52. doi: 10.3390/insects7040052. PubMed DOI PMC

Morais S.A., Urbinatti P.R., Sallum M.A.M., Kuniy A.A., Moresco G.G., Fernandes A., Nagaki S.S., Natal D. Brazilian mosquito (Diptera: Culicidae) fauna: I. Anopheles species from Porto Velho, Rondônia state, western Amazon, Brazil. Revista do Instituto de Medicina Tropical de São Paulo. 2012;54:331–335. doi: 10.1590/S0036-46652012000600008. PubMed DOI

Thatcher B.D., Tadei W.P. Malaria vectors in the Brazilian Amazon: Anopheles of the subgenus Nyssorhynchus. Revista do Instituto de Medicina Tropical de São Paulo. 2000;42:87–94. PubMed

Corbel V., Achee N.L., Chandre F., Coulibaly M.B., Dusfour I., Fonseca D.M., Grieco J., Juntarajumnong W., Lenhart A., Martins A.J., et al. Tracking Insecticide Resistance in Mosquito Vectors of Arboviruses: The Worldwide Insecticide resistance Network (WIN) PLOS Neglected Trop. Dis. 2016;10:e0005054. doi: 10.1371/journal.pntd.0005054. PubMed DOI PMC

Achee N.L., Grieco J.P., Vatandoost H., Seixas G., Pinto J., Ching-Ng L., Martins A.J., Juntarajumnong W., Corbel V., Gouagna C., et al. Alternative strategies for mosquito-borne arbovirus control. PLOS Neglected Trop. Dis. 2019;13:e0006822 PubMed PMC

Peters R.A. Croonian Lecture—Lethal synthesis. Proc. R. Soc. London. Ser. B: Boil. Sci. 1952;139:143–170. PubMed

Yanagisawa N. [The nerve agent sarin: History, clinical manifestations, and treatment] Brain Nerve. 2014;66:561–569. PubMed

Antonijević B., Stojiljkovic M.P. Unequal Efficacy of Pyridinium Oximes in Acute Organophosphate Poisoning. Clin. Med. Res. 2007;5:71–82. doi: 10.3121/cmr.2007.701. PubMed DOI PMC

Aroniadou-Anderjaska V., Figueiredo T.H., Apland J.P., Prager E.M., Pidoplichko V.I., Miller S.L., Braga M.F.M. Long-term neuropathological and behavioral impairments after exposure to nerve agents. Ann. N. Y. Acad. Sci. 2006;1374:17–28. doi: 10.1111/nyas.13028. PubMed DOI PMC

Aroniadou-Anderjaska V., Figueiredo T.H., Apland J.P., Qashu F., Braga M.F. Primary brain targets of nerve agents: The role of the amygdala in comparison to the hippocampus. NeuroToxicology. 2009;30:772–776. doi: 10.1016/j.neuro.2009.06.011. PubMed DOI PMC

Moshiri M., Darchini-Maragheh E., Balali-Mood M. Advances in toxicology and medical treatment of chemical warfare nerve agents. DARU J. Pharm. Sci. 2012;20:81. doi: 10.1186/2008-2231-20-81. PubMed DOI PMC

Čolović M.B., Krstić D.Z., Lazarević-Pašti T.D., Bondžić A.M., Vasić V.M. Acetylcholinesterase inhibitors: Pharmacology and toxicology. Curr. Neuropharmacol. 2013;11:315–335. doi: 10.2174/1570159X11311030006. PubMed DOI PMC

Wilson I.B., Ginsburg S. Reactivation of alkylphosphate inhibited acetylcholinesterase by bis quaternary derivatives of 2-PAM and 4-PAM. Biochem. Pharmacol. 1959;1:200–206. doi: 10.1016/0006-2952(59)90099-1. DOI

Cannard K.J. The acute treatment of nerve agent exposure. Neurol. Sci. 2006;249:86–94. doi: 10.1016/j.jns.2006.06.008. PubMed DOI

Kuca K., Jun D., Musilek K. Structural Requirements of Acetylcholinesterase Reactivators. Mini-Reviews Med. Chem. 2006;6:269–277. doi: 10.2174/138955706776073510. PubMed DOI

Worek F., Wille T., Koller M., Thiermann H. Structural requirements for effective oximes – Evaluation of kinetic in vitro data with phosphylated human AChE and structurally different oximes. Chem. Interactions. 2013;203:125–128. doi: 10.1016/j.cbi.2012.07.003. PubMed DOI

Milatovic D., Jokanović M. Handbook of Toxicology of Chemical Warfare Agents. Elsevier BV; San Diego, CA, USA: 2009. Pyridinium Oximes as Cholinesterase Reactivators in the Treatment of OP Poisoning; pp. 985–996.

Saint-André G., Kliachyna M., Kodepelly S., Louise-Leriche L., Gillon E., Renard P.-Y., Nachon F., Baati R., Wagner A. Design, synthesis and evaluation of new α-nucleophiles for the hydrolysis of organophosphorus nerve agents: Application to the reactivation of phosphorylated acetylcholinesterase. Tetrahedron. 2011;67:6352–6361. doi: 10.1016/j.tet.2011.05.130. DOI

Sit R.K., Radić Z., Gerardi V., Zhang L., Garcia E., Katalinić M., Amitai G., Kovarik Z., Fokin V.V., Sharpless K.B., et al. New Structural Scaffolds for Centrally Acting Oxime Reactivators of Phosphylated Cholinesterases*. J. Boil. Chem. 2011;286:19422–19430. doi: 10.1074/jbc.M111.230656. PubMed DOI PMC

Musilek K., Kuca K., Jun D., Dohnal V., Dolezal M. Synthesis of the novel series of bispyridinium compounds bearing (E)-but-2-ene linker and evaluation of their reactivation activity against chlorpyrifos-inhibited acetylcholinesterase. Bioorganic Med. Chem. Lett. 2006;16:622–627. doi: 10.1016/j.bmcl.2005.10.059. PubMed DOI

Timperley C.M., Banks R.E., Young I.M., Haszeldine R.N. Synthesis of some fluorine-containing pyridinealdoximes of potential use for the treatment of organophosphorus nerve-agent poisoning. J. Fluor. Chem. 2011;132:541–547. doi: 10.1016/j.jfluchem.2011.05.028. DOI

Jokanovic M. Structure-Activity Relationship and Efficacy of Pyridinium Oximes in the Treatment of Poisoning with Organophosphorus Compounds: A Review of Recent Data. Curr. Top. Med. Chem. 2012;12:1775–1789. doi: 10.2174/1568026611209061775. PubMed DOI

Acharya J., Gupta A.K., Mazumder A., Dubey D.K. In-vitro regeneration of sarin inhibited electric eel acetylcholinesterase by bis-pyridinium oximes bearing xylene linker. Eur. J. Med. Chem. 2009;44:1326–1330. doi: 10.1016/j.ejmech.2008.02.020. PubMed DOI

Acharya J., Dubey D.K., Srivastava A.K., Raza S.K. In vitro reactivation of sarin-inhibited human acetylcholinesterase (AChE) by bis-pyridinium oximes connected by xylene linkers. Toxicol. Vitr. 2011;25:251–256. doi: 10.1016/j.tiv.2010.07.024. PubMed DOI

Musilek K., Jun D., Cabal J., Kassa J., Gunn-Moore F., Kuca K. Design of a Potent Reactivator of Tabun-Inhibited AcetylcholinesteraseSynthesis and Evaluation of (E)-1-(4-Carbamoylpyridinium)-4-(4-hydroxyiminomethylpyridinium)-but-2-ene Dibromide (K203) J. Med. Chem. 2007;50:5514–5518. doi: 10.1021/jm070653r. PubMed DOI

Cavalcante S.F.A., Kitagawa D.A.S., Rodrigues R.B., Bernardo L.B., da Silva T.N., dos Santos W.V., Correa A.B.A., de Almeida J.S.F.D., França T.C.C., Kuča K., et al. Synthesis and in vitro evaluation of neutral aryloximes as reactivators of Electrophorus eel Acetylcholinesterase inhibited by NEMP, a VX surrogate. Chem. Biol. Interact. 2019;309 doi: 10.1016/j.cbi.2019.05.048. in press. PubMed DOI

Sahu A.K., Sharma R., Gupta B., Musilek K., Kuca K., Acharya J., Ghosh K.K. Oxime-mediated in vitro reactivation kinetic analysis of organophosphates-inhibited human and electric eel acetylcholinesterase. Toxicol. Mech. Methods. 2016;26:1–8. doi: 10.3109/15376516.2016.1143070. PubMed DOI

Worek F., Reiter G., Eyer P., Szinicz L. Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Arch. Toxicol. 2002;76:523–529. doi: 10.1007/s00204-002-0375-1. PubMed DOI

Ribeiro T.S., Prates A., Alves S.R., Oliveira-Silva J.J., Riehl C.A.S., Figueroa-Villar J.D. The effect of neutral oximes on the reactivation of human acetylcholinesterase inhibited with paraoxon. J. Braz. Chem. Soc. 2012;23:1216–1225. doi: 10.1590/S0103-50532012000700004. DOI

Ellman G.L., Courtney K., Andres V., Featherstone R.M. A new and rapid colorimetric determination of acetylcholinesterase activity. Biochem. Pharmacol. 1961;7:88–95. doi: 10.1016/0006-2952(61)90145-9. PubMed DOI

Cavalcante S., Kitagawa D., Rodrigues R., Cardozo M., Paula R., Correa A.B., Simas A. Straightforward, economical procedures for microscale ellman’s test for cholinesterase inhibition and reactivation. Química Nova. 2018;41:1192–1195. doi: 10.21577/0100-4042.20170278. DOI

Pohanka M., Hrabinová M., Kuca K., Simonato J.-P. Assessment of Acetylcholinesterase Activity Using Indoxylacetate and Comparison with the Standard Ellman’s Method. Int. J. Mol. Sci. 2011;12:2631–2640. doi: 10.3390/ijms12042631. PubMed DOI PMC

Sit R.K., Fokin V.V., Amitai G., Sharpless K.B., Taylor P., Radić Z. Imidazole aldoximes effective in assisting butyrylcholinesterase catalysis of organophosphate detoxification. J. Med. Chem. 2014;57:1378–1389. doi: 10.1021/jm401650z. PubMed DOI PMC

Radić Z., Sit R.K., Kovarik Z., Berend S., Garcia E., Zhang L., Amitai G., Green C., Radić B., Fokin V.V., et al. Refinement of Structural Leads for Centrally Acting Oxime Reactivators of Phosphylated Cholinesterases*. J. Boil. Chem. 2012;287:11798–11809. doi: 10.1074/jbc.M111.333732. PubMed DOI PMC

Bajgar J. Organophosphates/Nerve Agent Poisoning: Mechanism of Action, Diagnosis, Prophylaxis, And Treatment. Adv. Clin. Chem. 2004;38:151–216. PubMed

Tattersall J.E.H. Ion channel blockade by oximes and recovery of diaphragm muscle from soman poisoning in vitro. Br. J. Pharmacol. 1993;108:1006–1015. doi: 10.1111/j.1476-5381.1993.tb13498.x. PubMed DOI PMC

Ozgun D.O., Yamali C., Gul H.I., Taslimi P., Gulcin I., Yanik P.D., Supuran C.T. Inhibitory effects of isatin Mannich bases on carbonic anhydrases, acetylcholinesterase, and butyrylcholinesterase. J. Enzym. Inhib. Med. Chem. 2016;31:1–4. doi: 10.3109/14756366.2016.1149479. PubMed DOI

Chandra M.P., Rao J.V. Biological evaluation of schiff bases of new isatin derivatives for anti alzheimer’s activity. [(accessed on 23 August 2019)];Asian J. Pharm. Clin. Res. 2014 7:114–117. Available online: https://innovareacademics.in/journals/index.php/ajpcr/article/view/966.

Barcelos R.P., Lima Portella R., Lugokenski T.H., Rosa E.J.F., Amaral G.P., Garcia L.F.M., Bresolin L., Carratu V., Soares F.A.A., Vargas Barbosa N.B. Isatin-3-N4-benzilthiosemicarbazone, a non-toxic thiosemicarbazone derivative, protects and reactivates rat and human cholinesterases inhibited by methamidophos in vitro and in silico. Toxicol. In Vitro. 2012;26:1030–1039. doi: 10.1016/j.tiv.2012.04.008. PubMed DOI

Boar B.R., Cross A.J. Isatin Derivatives, Processes for the Preparation Thereof and Pharmacautical Composition Comprising the Same. WO 9312085. 1993 Jun 24;

Bridges T.M., Marlo J.E., Niswender C.M., Jones C.K., Jadhav S.B., Gentry P.R., Plumley H.C., Weaver C.D., Conn P.J., Lindsley C.W. Discovery of the first highly M5-preferring muscarinic acetylcholine receptor ligand, an M5 positive allosteric modulator derived from a series of 5-trifluoromethoxy N-benzyl isatins. J. Med. Chem. 2009;52:3445–3448. doi: 10.1021/jm900286j. PubMed DOI PMC

De Paula R.L., De Almeida J.S.F.D., Cavalcante S.F.A., Gonçalves A.S., Simas A.B.C., Franca T.C.C., Valis M., Kuca K., Nepovimova E., Granjeiro J.M. Molecular Modeling and In Vitro Studies of a Neutral Oxime as a Potential Reactivator for Acetylcholinesterase Inhibited by Paraoxon. Molecules. 2018;23:2954. doi: 10.3390/molecules23112954. PubMed DOI PMC

Cavalcante S., Simas A., Kitagawa D., Bernardo L., Rodrigues R., Correa A., Paula R., Freitas L., Diz de Almeida J., França T., et al. Derivados da Indolin-2-ona e Seus Intermediários, Produtos, Métodos de Obtenção e Usos. BR1020180750046. 2018 Dec 3;

Zorbaz T., Malinak D., Mariković N., Maček Hrvak N., Zandona A., Novotny M., Sharka A., Andrys R., Benkova M., Soukup O., et al. Pyridinium Oximes with Ortho-Positioned Chlorine Moiety Exhibit Improved Physicochemical Properties and Efficient Reactivation of Human Acetylcholinesterase Inhibited by Several Nerve Agents. J. Med. Chem. 2018;61:10753–10766. doi: 10.1021/acs.jmedchem.8b01398. PubMed DOI

Zorbaz T., Malinak D., Kuča K., Musilek K., Kovarik Z. Butyrylcholinesterase inhibited by nerve agents is efficiently reactivated with chlorinated pyridinium oximes. Chem. Biol. Interact. 2019;307:16–20. doi: 10.1016/j.cbi.2019.04.020. PubMed DOI

Bassetto M., Ferla S., Pertusati F. Polyfluorinated groups in medicinal chemistry. Futur. Med. Chem. 2015;7:527–546. doi: 10.4155/fmc.15.5. PubMed DOI

Biffinger J.C., Kim H.W., DiMagno S.G. The Polar Hydrophobicity of Fluorinated Compounds. ChemBioChem. 2004;5:622–627. doi: 10.1002/cbic.200300910. PubMed DOI

Design, synthesis, in silico studies and in vitro evaluation of isatin-pyridine oximes hybrids as novel acetylcholinesterase reactivators

Trends in the Recent Patent Literature on Cholinesterase Reactivators (2016-2019)

Acetylcholinesterase: The "Hub" for Neurodegenerative Diseases and Chemical Weapons Convention

Biodegradation of Organophosphorus Compounds Predicted by Enzymatic Process Using Molecular Modelling and Observed in Soil Samples Through Analytical Techniques and Microbiological Analysis: A Comparison