Obidoxime is a member of the

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

family used to treat

nerve gas 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 ...

poisoning. Oximes are drugs known for their ability to reverse the binding of

organophosphorus Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective in ...

compounds to the enzyme acetylcholinesterase (AChE). AChE is an enzyme that removes acetylcholine from the synapse after it creates the required stimulation on the next

nerve cell A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. No ...

. If it gets inhibited, acetylcholine is not removed after the stimulation and multiple stimulations are made, resulting in muscle contractions and paralysis. Organophosphates (such as nerve gases) are well-known inhibitors of AChE. They bind to a specific place on the enzyme and prevent it from functioning normally by changing the OH group on the serine residue and by protonating (quaternary

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

, R₄N⁺) the nearby nitrogen atom located in the

histidine Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the d ...

residue.

Function

Oximes such as obidoxime,

pralidoxime Pralidoxime (2-pyridine aldoxime methyl chloride) or 2-PAM, usually as the chloride or iodide salts, belongs to a family of compounds called oximes that bind to organophosphate-inactivated acetylcholinesterase. It is used to treat organophosph ...

and asoxime (HI-6) are used to restore enzyme functionality. They have greater affinity for the organic phosphate residue than the enzyme and they remove the phosphate group, restore the OH to serine and turn nitrogen from histidine back into its R₃N form (tertiary nitrogen). This results in full enzyme recovery and the phosphate-oxime compound is eliminated from the organism via

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...

. Obidoxime is more potent than pralidoxime and diacetyl-monoxime.

Side effects

Oximes like these do have side effects and they include

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

damage,

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

damage,

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...

, but they are very efficient

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 ...

s to nerve gas poisoning. Usually treatment of poisoning includes the use of atropine, which can slow down the action of the poison, giving more time to apply the oxime.

References

CAS Registry/EC Number (RN)
{{Acetylcholine metabolism and transport modulators Cholinesterase reactivators Chemical substances for emergency medicine Ethers Aldoximes Quaternary ammonium compounds