The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters:
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, including humans, so its use has been banned or restricted in most countries. The basic structure is shared by parathion methyl.
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.
Chlorfenvinphos is an organophosphorus compound that was widely used as an insecticide and an acaricide. The molecule itself can be described as an enol ester derived from dichloroacetophenone and diethylphosphonic acid. Chlorfenvinphos has been included in many products since its first use in 1963. However, because of its toxic effect as a cholinesterase inhibitor it has been banned in several countries, including the United States and the European Union. Its use in the United States was cancelled in 1991.
In organic chemistry, organophosphates are a class of organophosphorus compounds with the general structure O=P(OR)3, a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid.
Organophosphate poisoning is poisoning due to organophosphates (OPs). Organophosphates are used as insecticides, medications, and nerve agents. Symptoms include increased saliva and tear production, diarrhea, vomiting, small pupils, sweating, muscle tremors, and confusion. While onset of symptoms is often within minutes to hours, some symptoms can take weeks to appear. Symptoms can last for days to weeks.
Paraoxon is a parasympathomimetic which acts as an cholinesterase inhibitor. It is an organophosphate oxon, and the active metabolite of the insecticide parathion. It is also used as an ophthalmological drug against glaucoma. Paraoxon is one of the most potent acetylcholinesterase-inhibiting insecticides available, around 70% as potent as the nerve agent sarin, and so is now rarely used as an insecticide due to the risk of poisoning to humans and other animals. Paraoxon has been used by scientists to study acute and chronic effects of organophosphate intoxication. It is easily absorbed through skin, and was allegedly used as an assassination weapon by the apartheid-era South African chemical weapons program Project Coast.
In biochemistry, an acetylesterase is a class of enzyme which catalyzes the hydrolysis of acetic esters into an alcohol and acetic acid:
Aryldialkylphosphatase is a metalloenzyme that hydrolyzes the triester linkage found in organophosphate insecticides:
Acetylcholinesterase inhibitors (AChEIs) also often called cholinesterase inhibitors, inhibit the enzyme acetylcholinesterase from breaking down the neurotransmitter acetylcholine into choline and acetate, thereby increasing both the level and duration of action of acetylcholine in the central nervous system, autonomic ganglia and neuromuscular junctions, which are rich in acetylcholine receptors. Acetylcholinesterase inhibitors are one of two types of cholinesterase inhibitors; the other being butyryl-cholinesterase inhibitors. Acetylcholinesterase is the primary member of the cholinesterase enzyme family.
Demeton, sold as an amber oily liquid with a sulphur like odour under the name Systox, is an organophosphate derivative causing irritability and shortness of breath to individuals repeatedly exposed. It was used as a phosphorothioate insecticide and acaricide and has the chemical formula C8H19O3PS2. Although it was previously used as an insecticide, it is now largely obsolete due to its relatively high toxicity to humans. Demeton consists of two components, demeton-S and demeton-O in a ratio of approximately 2:1 respectively. The chemical structure of demeton is closely related to military nerve agents such as VX and a derivative with one of the ethoxy groups replaced by methyl was investigated by both the US and Soviet chemical-weapons programs under the names V.sub.X and GD-7.
Terbufos is a chemical compound used in insecticides and nematicides. It is part of the chemical family of organophosphates. It is a clear, colourless to pale yellow or reddish-brown liquid and sold commercially as granulate.
Dimethylcarbamoyl fluoride is a chemical compound that can be produced by fluorination of dimethylcarbamoyl chloride with potassium fluoride. It's a colorless liquid that is soluble and stable in water.
Ro 3-0422 is an extremely potent organophosphate acetylcholinesterase inhibitor. It is extremely toxic. The intravenous LD50 is 20 μg/kg in mice. It is over 300 times more potent than neostigmine.
Ro 3-0419 is a highly toxic organophosphate acetylcholinesterase inhibitor. It is the neutral analog of Ro 3-0422. Although Ro 3-0419 is less potent than Ro 3-0422, it does not have a positively charged nitrogen atom, resulting in its ability to cross the blood brain barrier to inhibit cholinesterases in the brain. The intravenous LD50 of Ro 3-0419 is 1 mg/kg in mice.
Schradan, named after Gerhard Schrader, is an obsolete organophosphate insecticide. Schradan itself is a weak cholinesterase inhibitor and requires metabolic activation to become active.
Armine is an irreversible acetylcholinesterase inhibitor. It is the ethylphosphonate analog of paraoxon.
GD-42 (methylsulfomethylate) is an irreversible acetylcholinesterase inhibitor. It has a positively charged sulfonium group.
Ro 3-0412 is an acetylcholinesterase inhibitor. It is the organophosphate analog of neostigmine.
Cholinesterase reactivators are drugs that reverse the inhibition of cholinesterase by organophosphates or sulfonates. They are used as antidote for treating organophosphate insecticide and nerve agent poisoning.
