Acetylcholinesterase inhibitors (AChEIs) also often called cholinesterase inhibitors,
inhibit the enzyme
acetylcholinesterase
Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme
Enzymes () are proteins that a ...
from
breaking down
"Breaking Down" is a song by American rock band I Prevail, released as the second single from their second studio album ''Trauma''. In July 2019, it peaked at number three on the '' Billboard'' Mainstream Rock Songs chart.
Background
The song w ...
the
neurotransmitter
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell.
Neuro ...
acetylcholine
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...
into
choline Choline is an essential nutrient for humans and many other animals. Choline occurs as a cation that forms various salts (X− in the depicted formula is an undefined counteranion). Humans are capable of some ''de novo synthesis'' of choline but re ...
and
acetate
An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...
,
thereby increasing both the level and duration of action of acetylcholine in the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
,
autonomic ganglia
An autonomic ganglion is a cluster of nerve cell bodies (a ganglion) in the autonomic nervous system
The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that s ...
and
neuromuscular junction
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber.
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction.
Muscles require innervation to ...
s, which are rich in
acetylcholine receptor
An acetylcholine receptor (abbreviated AChR) is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter.
Classification
Like other transmembrane receptors, acetylcholine receptors are classified according ...
s.
Acetylcholinesterase inhibitors are one of two types of
cholinesterase inhibitor
Cholinesterase inhibitors (ChEIs), also known as anti-cholinesterase, are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine. This increases the amount of the acetylcholine or butyrylcholine in the syn ...
s; the other being
butyryl-cholinesterase inhibitors.
Acetylcholinesterase
Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme
Enzymes () are proteins that a ...
is the primary member of the
cholinesterase enzyme family.
Acetylcholinesterase inhibitors are classified as reversible, irreversible, or quasi-irreversible (also called pseudo-irreversible).
Mechanism of action
Organophosphates
Organophosphates like
TEPP
Tetraethyl pyrophosphate, abbreviated TEPP, is an organophosphate compound with the formula . It is the tetraethyl derivative of pyrophosphate (P2O74-). It is a colorless oil that solidifies near room temperature. It is used as an insecticide. Th ...
and
sarin
Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.[cholinesterase
The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters:
: an acylcholine + H2O = choline + a carboxylate
Several of these serve as neurotransmitters ...]
s, enzymes that hydrolyze the neurotransmitter
acetylcholine
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...
.
The active centre of cholinesterases feature two important sites, namely the anionic site and the esteratic site. After the binding of acetylcholine to the anionic site of the cholinesterase, the acetyl group of acetylcholine can bind to the esteratic site. Important amino acid residues in the esteratic site are a glutamate, a histidine, and a serine. These residues mediate the
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of the acetylcholine.
At the esteratic site the acetylcholine is cleaved, which results in a free choline moiety and an acetylated cholinesterase. This acetylated state requires hydrolysis to regenerate itself.
Inhibitors like TEPP modify the serine residue in the esteratic site of the cholinesterase.
This
phosphorylation
In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...
inhibits the binding of the acetyl group of the acetylcholine to the esteratic site of the cholinesterase. Because the acetyl group can't bind the cholinesterase, the acetylcholine can't be cleaved. Therefore, the acetylcholine will remain intact and will accumulate in the synapses. This results in continuous activation of
acetylcholine receptor
An acetylcholine receptor (abbreviated AChR) is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter.
Classification
Like other transmembrane receptors, acetylcholine receptors are classified according ...
s, which leads to the acute symptoms of TEPP poisoning. The phosphorylation of cholinesterase by TEPP (or any other organophosphate) is irreversible. This makes the inhibition of the cholinesterase permanent.
The cholinesterase gets irreversible phosphorylated according to the following reaction scheme
E + PX <=> E-PX -> _3EP + X
In this reaction scheme the E indicates the cholinesterase, PX the TEPP molecule, E–PX the reversible phosphorylated cholinesterase, ''k''
3 the reaction rate of the second step, EP the phosphorylated cholinesterase and X the leaving group of the TEPP.
The irreversible phosphorylation of the cholinesterase occurs in two steps. In the first step the cholinesterase gets reversibly phosphorylated. This reaction is very fast. Then the second step takes place. The cholinesterase forms a very stable complex with TEPP, in which TEPP is covalently bound to the cholinesterase. This is a slow reaction. But after this step the cholinesterase is irreversibly inhibited.
The time dependent irreversible inhibition of the cholinesterase can be described by the following equation.
:
In this formula, ''E'' is the remaining enzyme activity, ''E''
0 is the initial enzyme activity, ''t'' is the time interval after mixing of the cholinesterase and the TEPP, ''K''
''I'' is the dissociation constant for cholinesterase-TEPP complex (E–PX) and I is the TEPP concentration.
The reaction mechanism and the formula above are both also compatible for other organophosphates. The process occurs in the same way.
Furthermore, certain organophosphates can cause OPIDN, organophosphate-induced delayed polyneuropathy. This is a disease, which is characterized by degeneration of axons in the peripheral and central nervous system. This disease will show a few weeks after contamination with the organophosphate. It is believed that the neuropathy target esterase (NTE) is affected by the organophosphate which induces the disease. However, there are no references found, which indicate that TEPP is one of the organophosphates that can cause OPIDN.
Uses
Acetylcholinesterase inhibitors:
* Occur naturally as
venoms
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
and
poison
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
s (e.g.
onchidal
Onchidal is a naturally occurring neurotoxin produced as a defensive secretion by the mollusc '' Onchidella binneyi'' and several other related species in ''Onchidella'', a genus of small, air-breathing sea slugs. It acts as an irreversible acet ...
)
* Are used as weapons (
nerve agent
Nerve agents, sometimes also called nerve gases, are a class of organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (AChE), an enzyme that ...
s)
* Are used medicinally:
** To treat
myasthenia gravis
Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...
. In myasthenia gravis, they are used to increase neuromuscular transmission.
** To treat
glaucoma
Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...
** To treat
postural tachycardia syndrome
Postural orthostatic tachycardia syndrome (POTS) is a condition characterized by an abnormally large increase in heart rate upon standing. Symptoms may include lightheadedness, brain fog, blurred vision, weakness, fatigue, headaches, heart pa ...
** As an
antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...
to
anticholinergic
Anticholinergics (anticholinergic agents) are substances that block the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system.
These agents inhibit the parasympathetic nervous system ...
poisoning
** To reverse the effect of non-depolarising muscle relaxants
** To treat neuropsychiatric symptoms of diseases such as
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
, particularly
apathy
Apathy is a lack of feeling, emotion, interest, or concern about something. It is a state of indifference, or the suppression of emotions such as concern, excitement, motivation, or passion. An apathetic individual has an absence of intere ...
** To increase chances of
lucid dreaming
A lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment; however, this is n ...
(by prolonging
REM sleep
Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream viv ...
)
** To treat Alzheimer's disease, the
Lewy body dementia
Lewy body dementias are two similar and common subtypes of dementia—dementia with Lewy bodies (DLB) and
Parkinson's disease dementia (PDD). Both are characterized by changes in thinking, movement, behavior, and mood. The two conditions have sim ...
s and
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...
. In these
neurodegenerative conditions AChEIs are primarily used to treat the cognitive (memory and learning deficits mostly) symptoms of
dementia
Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
. These symptoms are attenuated due to the role of acetylcholine in cognition in the
CNS. There is some evidence to suggest that AChEIs may attenuate psychotic symptoms (especially visual hallucinations) in Parkinson's disease.
** To treat cognitive impairments in patients with
schizophrenia
Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...
. There is some evidence to suggest efficacy in treating positive, negative and affective symptoms.
** As a treatment for autism and to increase the percentage of
rapid eye movement sleep
Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream viv ...
in autistic children, in line with the mechanism by which they encourage lucid dreaming.
* Are used as (e.g.
malathion
Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion.
Pesticide use
Malathion is a pesti ...
):
** : The hunt for
resistance genes in ''
Rhipicephalus microplus
The Asian blue tick (''Rhipicephalus'' (''Boophilus'') ''microplus'', ''Rhipicephalus microplus'', or ''Boophilus microplus'') is an economically important tick that parasitises a variety of livestock species especially cattle, on which it is th ...
'' has been hampered by
high copy number in the three
AChEs
Patrick Price (born July 18, 1994) known by his video game moniker ACHES, is an American professional esports player. Price is best known for playing '' Call of Duty''.
Career
Price won the Call of Duty Championship 2014 with compLexity Gaming ...
involved.
Bellgard et al. 2012, Temeyer et al. 2012, and Bendele et al. 2015 all investigate such populations and encounter difficulty confirming the involvement of these three due to copy number.
Guideline recommendations
The clinical guidelines for medication management in people with dementia recommend trialing an AChE inhibitor for people with early to mid stage dementia. These guidelines, known as the
Medication Appropriateness Tool for Comorbid Health conditions in Dementia (MATCH-D), suggest that these medicines are at least considered.
Side effects
Some major effects of cholinesterase inhibitors:
* Actions on the
parasympathetic nervous system
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
, (the
parasympathetic branch of the
autonomic nervous system
The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
) may cause
bradycardia
Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, a ...
,
hypotension
Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dias ...
,
hypersecretion 440px
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...
,
bronchoconstriction
Bronchoconstriction is the constriction of the airways in the lungs due to the tightening of surrounding smooth muscle, with consequent coughing, wheezing, and shortness of breath.
Causes
The condition has a number of causes, the most common bei ...
,
GI tract hypermotility, and decrease
intraocular pressure
Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated to ...
, increase lower esophageal sphincter (LES) tone
*
Cholinergic crisis
A cholinergic crisis is an over-stimulation at a neuromuscular junction due to an excess of acetylcholine (ACh), as a result of the inactivity of the AChE enzyme, which normally breaks down acetylcholine.
Symptoms and diagnosis
As a result of ch ...
.
* Actions on the neuromuscular junction may result in prolonged
muscle contraction
Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as ...
.
* The effects of
neostigmine
Neostigmine, sold under the brand name Bloxiverz, among others, is a medication used to treat myasthenia gravis, Ogilvie syndrome, and urinary retention without the presence of a blockage. It is also used in anaesthesia to end the effects of n ...
on postoperative nausea and vomiting are controversial and there is not a clear linkage in clinical practice, however, there is good evidence to support the reduction in risk when anticholinergic agents are administered.
Administration of reversible cholinesterase inhibitors is contraindicated with those that have
urinary retention
Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include loss of bladd ...
due to
urethral obstruction
Urinary tract obstruction is a urologic disease consisting of a decrease in the free passage of urine through one or both ureters and/or the urethra. It is a cause of urinary retention. Complete obstruction of the urinary tract requires prompt tr ...
.
Overdose
Hyperstimulation of
nicotinic
Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral ner ...
and
muscarinic receptor
Muscarinic acetylcholine receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end-rec ...
s.
Titration phase
When used in the central nervous system to alleviate neurological symptoms, such as
rivastigmine
Rivastigmine (sold under the trade name Exelon among others) is a cholinesterase inhibitor used for the treatment of mild to moderate Alzheimer's disease. The drug can be administered orally or via a transdermal patch; the latter form reduces th ...
in
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
, all cholinesterase inhibitors require doses to be increased gradually over several weeks, and this is usually referred to as the ''titration phase''. Many other types of drug treatments may require a titration or stepping up phase. This strategy is used to build tolerance to adverse events or to reach a desired clinical effect.
This also prevents accidental overdose and is therefore recommended when initiating treatment with drugs that are extremely potent and/or toxic (drugs with a low
therapeutic index
The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes ...
).
Examples
Reversible inhibitor
Compounds which function as
reversible competitive
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
or
noncompetitive inhibitors of cholinesterase are those most likely to have therapeutic uses. These include:
* Some
organophosphate
In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...
s not listed under "Irreversible" below
*
Carbamate
In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formally o ...
s
**
Physostigmine
Physostigmine (also known as eserine from ''éséré'', the West African name for the Calabar bean) is a highly toxic parasympathomimetic alkaloid, specifically, a reversible cholinesterase inhibitor. It occurs naturally in the Calabar bean and ...
**
Neostigmine
Neostigmine, sold under the brand name Bloxiverz, among others, is a medication used to treat myasthenia gravis, Ogilvie syndrome, and urinary retention without the presence of a blockage. It is also used in anaesthesia to end the effects of n ...
**
Pyridostigmine
Pyridostigmine is a medication used to treat myasthenia gravis and underactive bladder. It is also used together with atropine to end the effects of neuromuscular blocking medication of the non-depolarizing type. It is typically given by mouth ...
**
Ambenonium
**
Demecarium
**
Rivastigmine
Rivastigmine (sold under the trade name Exelon among others) is a cholinesterase inhibitor used for the treatment of mild to moderate Alzheimer's disease. The drug can be administered orally or via a transdermal patch; the latter form reduces th ...
*
Phenanthrene
Phenanthrene is a polycyclic aromatic hydrocarbon (PAH) with formula C14H10, consisting of three fused benzene rings. It is a colorless, crystal-like solid, but can also appear yellow. Phenanthrene is used to make dyes, plastics and pesticides, e ...
derivatives
**
Galantamine
Galantamine is used for the treatment of cognitive decline in mild to moderate Alzheimer's disease and various other memory impairments. It is an alkaloid that has been isolated from the bulbs and flowers of ''Galanthus nivalis'' (Common snowdro ...
*
Caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
– noncompetitive (also an
adenosine
Adenosine ( symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9-glycosidic bond. Adenosine is one of the four nucleoside building ...
receptor antagonist)
*
Rosmarinic acid
Rosmarinic acid, named after rosemary (''Salvia rosmarinus'' Linn.), is a polyphenol constituent of many culinary herbs, including rosemary (''Salvia rosmarinus'' L.), perilla (''Perilla frutescens'' L.), Salvia officinalis, sage (''Salvia offic ...
– ester of
caffeic acid
Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, one ...
. Found in plants species of family
Lamiaceae
The Lamiaceae ( )
or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...
.
*
Alpha-pinene
α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...
– noncompetitive reversible
*
Piperidine
Piperidine is an organic compound with the molecular formula (CH2)5NH. This heterocyclic compound, heterocyclic amine consists of a six-membered ring containing five methylene bridges (–CH2–) and one amine bridge (–NH–). It is a colorless ...
s
**
Donepezil
Donepezil, sold under the brand name Aricept among others, is a medication used to treat dementia of the Alzheimer's disease, Alzheimer's type. It appears to result in a small benefit in mental function and ability to function. Use, however, ha ...
*
Tacrine
Tacrine is a centrally acting acetylcholinesterase inhibitor and indirect cholinergic agonist (parasympathomimetic). It was the first centrally acting cholinesterase inhibitor approved for the treatment of Alzheimer's disease, and was marketed un ...
, also known as tetrahydroaminoacridine (THA')
*
Edrophonium
Edrophonium is a readily reversible acetylcholinesterase inhibitor. It prevents breakdown of the neurotransmitter acetylcholine and acts by competitively inhibiting the enzyme acetylcholinesterase, mainly at the neuromuscular junction. It is so ...
*
Huperzine A
Huperzine A is a naturally occurring sesquiterpene alkaloid compound found in the firmoss ''Huperzia serrata'' and in varying quantities in other food ''Huperzia'' species, including ''H. elmeri'', ''H. carinat'', and ''H. aqualupian''. Huperzi ...
*
Ladostigil
*
Ungeremine
*
Lactucopicrin
Lactucopicrin (Intybin) is a bitter substance that has a sedative and analgesic effect, acting on the central nervous system. It is a sesquiterpene lactone, and is a component of lactucarium, derived from the plant ''Lactuca virosa'' (wild lettuce ...
*
Acotiamide
* Hybrid/bitopic ligands
Comparison table
Quasi-irreversible inhibitor
Compounds which function as
quasi-irreversible inhibitor For acetylcholinesterase (AChE), quasi-irreversible inhibitors are those that rapidly phosphorylate AChE. A subsequent internal dealkylation reaction may then occur, which, according to X-ray crystallography data, is suggestive of covalent bond form ...
s of cholinesterase are those most likely to have use as
chemical weapon
A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as a ...
s or
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s.
*
Organophosphates
In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...
**
Echothiophate
Echothiophate (Phospholine) is an irreversible acetylcholinesterase inhibitor.
Uses
It is used as an ocular antihypertensive in the treatment of chronic glaucoma and, in some cases, accommodative esotropia. It is available under several trade ...
**
Diisopropyl fluorophosphate
Diisopropyl fluorophosphate (DFP) or Isoflurophate is an oily, colorless liquid with the chemical formula C6H14FO3P. It is used in medicine and as an organophosphorus insecticide. It is stable, but undergoes hydrolysis when subjected to moisture. ...
**
Cadusafos
**
Chlorpyrifos
Chlorpyrifos (CPS), also known as Chlorpyrifos ethyl, is an organophosphate pesticide that has been used on crops, animals, and buildings, and in other settings, to kill several pests, including insects and worms. It acts on the nervous systems ...
**
Cyclosarin
Cyclosarin or GF (cyclohexyl methylphosphonofluoridate) is an extremely toxic substance used as a chemical weapon. It is a member of the '' G-series'' family of nerve agents, a group of chemical weapons discovered and synthesized by a German te ...
**
Dichlorvos
Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, commonly abbreviated as an DDVP) is an organophosphate widely used as an insecticide to control household pests, in public health, and protecting stored products from insects. The compound has bee ...
**
Dimethoate
Dimethoate is a widely used organophosphate insecticide and acaricide. It was patented and introduced in the 1950s by American Cyanamid. Like other organophosphates, dimethoate is an acetylcholinesterase inhibitor which disables cholinesterase, an ...
**
Metrifonate
Metrifonate (INN) or trichlorfon (USAN) is an irreversible organophosphate acetylcholinesterase inhibitor. It is a prodrug which is activated non-enzymatically into the active agent dichlorvos.
It is used as an insecticide.
According to the US ...
(irreversible)
**
Sarin
Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.[Soman
Soman (or GD, EA 1210, Zoman, PFMP, A-255, systematic name: ''O''-pinacolyl methylphosphonofluoridate) is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiti ...]
**
Tabun
**
VX
**
VE
**
VG
**
VM
**
Diazinon
Diazinon (IUPAC name: ''O'',''O''-Diethyl ''O''- -methyl-6-(propan-2-yl)pyrimidin-2-ylphosphorothioate, INN - Dimpylate), a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company ( ...
**
Malathion
Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion.
Pesticide use
Malathion is a pesti ...
**
Parathion
Parathion, also called parathion-ethyl or diethyl parathion and locally known as "Folidol", is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, incl ...
*
Carbamate
In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formally o ...
s
**
Aldicarb
Aldicarb is a carbamate insecticide which is the active substance in the pesticide Temik. It is effective against thrips, aphids, spider mites, lygus, fleahoppers, and leafminers, but is primarily used as a nematicide. Aldicarb is a cholineste ...
**
Bendiocarb
Bendiocarb is an acutely toxic carbamate insecticide used in public health and agriculture and is effective against a wide range of nuisance and disease vector insects. Many bendiocarb products are or were sold under the tradenames "Ficam" and "T ...
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Bufencarb
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Carbaryl
Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin tradem ...
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Carbendazim
Carbendazim is a widely used, systemic, broad-spectrum benzimidazole fungicide and a metabolite of benomyl. It is also employed as a casting worm control agent in amenity turf situations such as golf greens, tennis courts etc. and in some countr ...
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Carbetamide
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Carbofuran
Carbofuran is a carbamate pesticide, widely used around the world to control insects on a wide variety of field crops, including potatoes, corn and soybeans. It is a systemic insecticide, which means that the plant absorbs it through the r ...
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Carbosulfan
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Chlorbufam
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Chloropropham
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Ethiofencarb
Ethiofencarb is a carbamate insecticide which is useful in controlling aphids on hard and soft fruits and some vegetables. It is not as dangerous as organophosphorous pesticides, but is considered highly toxic to humans in the UK, moderately toxi ...
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Formetanate
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Methiocarb
Methiocarb is a carbamate pesticide (an acetylecholinesterase inhibitor) which is used as an insecticide, bird repellent, acaricide and molluscicide since the 1960s. Methiocarb has contact and stomach action on mites and neurotoxic effects on mo ...
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Methomyl
Methomyl is a carbamate insecticide introduced in 1966. It is highly toxic to humans, livestock, pets, and wildlife.
The EU and UK imposed a pesticide residue limit of 20 µg/kg for apples and oranges.
Methomyl is a common active ingredient in c ...
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Oxamyl
Oxamyl is a chemical used as a pesticide that comes in two forms: granulated and liquid. The granulated form has been banned in the United States. It is commonly sold under the trade name Vydate.
It is classified as an extremely hazardous subs ...
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Phenmedipham
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Pinmicarb
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Pirimicarb
Pirimicarb is a selective carbamate insecticide used to control aphids on vegetable, cereal and orchard crops by inhibiting acetylcholinesterase activity but does not affect useful predators such as ladybirds that eat them. It was originally d ...
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Propamocarb
Propamocarb is a systemic fungicide used for control of soil, root and leaf disease caused by oomycetes. It is used by watering or spraying. Propamocarb is absorbed and distributed through the plant's tissue.
Use
Propamocarb has fungicidal activi ...
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Propham
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Propoxur
Propoxur (Baygon) is a carbamate non-systemic insecticide introduced in 1959 with a fast knockdown and long residual effect used against turf, forestry, and household pests and fleas. It is also used in pest control for other domestic animals, ' ...
* Atypical inhibitors
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Onchidal
Onchidal is a naturally occurring neurotoxin produced as a defensive secretion by the mollusc '' Onchidella binneyi'' and several other related species in ''Onchidella'', a genus of small, air-breathing sea slugs. It acts as an irreversible acet ...
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Coumarins
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...
See also
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Pesticide poisoning
A pesticide poisoning occurs when pesticides, chemicals intended to control a pest, affect non-target organisms such as humans, wildlife, plant, or bees. There are three types of pesticide poisoning. The first of the three is a single and short- ...
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Parathion S
References
External links
*
Acetylcholinesterase: A gorge-ous enzymeQUite Interesting PDB Structure article a
PDBe
{{Acetylcholine metabolism and transport modulators