In this work, two oximes for the treatment of tabun-inhibited acetylcholinesterase (AChE; EC 3.1.1.7), K074 (1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) and K075 ((E)-1,4-bis(4-hydroxyiminomethylpyridinium)but-2-en dibromide), were tested in vitro as reactivators of AChE. Comparison was made with currently used AChE reactivators (pralidoxime, HI-6, methoxime and obidoxime). Human brain homogenate was taken as an appropriate source of the cholinesterases. As resulted, oxime K074 appears to be the most potent reactivator of tabun-inhibited AChE, with reactivation potency comparable to that of obidoxime. A second AChE reactivator, K075, does not attain as great a reactivation potency as K074, although its maximal reactivation (17%) was achieved at relevant concentrations for humans.

• MeSH
• Acetylcholinesterase metabolism   MeSH
• Enzyme Activation drug effects   MeSH
• Butanes chemistry   pharmacology   MeSH
• Cholinesterase Inhibitors toxicity   MeSH
• Humans MeSH
• Caudate Nucleus drug effects   enzymology   MeSH
• Obidoxime Chloride chemistry   pharmacology   MeSH
• Organophosphates toxicity   MeSH
• Oximes chemistry   pharmacology   MeSH
• Pralidoxime Compounds chemistry   pharmacology   MeSH
• Pyridinium Compounds chemistry   pharmacology   MeSH
• Cholinesterase Reactivators chemistry   pharmacology   MeSH
• In Vitro Techniques MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide MeSH Browser
• Acetylcholinesterase MeSH
• asoxime chloride MeSH Browser
• Butanes MeSH
• Cholinesterase Inhibitors MeSH
• K075 compound MeSH Browser
• N,N'-monomethylenebis(pyridiniumaldoxime) MeSH Browser
• Obidoxime Chloride MeSH
• Organophosphates MeSH
• Oximes MeSH
• pralidoxime MeSH Browser
• Pralidoxime Compounds MeSH
• Pyridinium Compounds MeSH
• Cholinesterase Reactivators MeSH
• tabun MeSH Browser

INTRODUCTION: Organophosphorus nerve agents inhibit the enzyme, acetylcholinesterase (AChE; EC 3.1.1.7). AChE reactivators (also known as oximes) are generally used for the reactivation of an inhibited enzyme. METHODS: Two new AChE reactivators--K033 and K027--were tested for their in vitro reactivation of sarin-inhibited pig-brain AChE. Their reactivation potencies were compared with the commercially available AChE reactivators, pralidoxime, obidoxime, and HI-6. RESULTS: Of the oximes tested, the newly developed oxime K027 achieved the highest reactivation potency (100%; concentration of the oxime -10(-2) M). However, oxime HI-6 (33%) and obidoxime (23%) seem to be the best AChE reactivators for human relevant doses (10(-4) M and lower). CONCLUSION: For human relevant doses, newly developed oximes (K027 and K033) do not surpass the reactivation potency of the most promising oxime, HI-6.

• MeSH
• Acetylcholinesterase metabolism   MeSH
• Antidotes pharmacology   MeSH
• Cholinesterase Inhibitors toxicity   MeSH
• Brain drug effects   enzymology   MeSH
• Obidoxime Chloride pharmacology   MeSH
• Oximes pharmacology   MeSH
• Pralidoxime Compounds pharmacology   MeSH
• Swine MeSH
• Pyridinium Compounds pharmacology   MeSH
• Cholinesterase Reactivators pharmacology   MeSH
• Sarin toxicity   MeSH
• In Vitro Techniques MeSH
• Research Design MeSH
• Dose-Response Relationship, Drug MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• 1-(4-hydroxyiminomethylpyridinium)-3-(carbamoylpyridinium) propane dibromide MeSH Browser
• 1,4-bis(2-hydroxyiminomethylpyridinium)butane MeSH Browser
• Acetylcholinesterase MeSH
• Antidotes MeSH
• asoxime chloride MeSH Browser
• Cholinesterase Inhibitors MeSH
• Obidoxime Chloride MeSH
• Oximes MeSH
• pralidoxime MeSH Browser
• Pralidoxime Compounds MeSH
• Pyridinium Compounds MeSH
• Cholinesterase Reactivators MeSH
• Sarin MeSH

Oximes in combination with atropine, are an integral part of the treatment of acute intoxications with organophosphorus insecticides or with the nerve agents such as tabun, sarin, soman, cyclosarin or VX. Organophosphorus compounds are extremely potent inhibitors of the enzyme acetylcholinesterase (AChE, 3.1.1.7). The pharmacological action of oximes is multiple: they are able to reactivate the inhibited AChE, but they affect acetylcholine release in peripheral and central cholinergic synapses, allosterically modulate the muscarinic receptors in peripheral and central synapses, and influence the nicotinic receptor-associated ion-channels. In our study, we have determined the acute toxicity of different structures of oximes after intramuscular application in mice. The acute toxicity of oximes is crucial for the assesment of a dose applied as a treatment for organophosphorus intoxications. We have tested 7 oximes of different structures (HS-6, K033, BI-6, MMB-4, K048, HI-6 and obidoxime ) and during our experiments we have observed the intoxication process including typical signs of intoxication, and times of death. K033 was the most toxic oxime with an LD50 of only 48 mg/kg, while the least toxic oxime - HI-6 - has an LD50 value of 671 mg/kg. All the oximes tested were of the bispyridinium type, with different length or shape of the connecting chain and positions of oxime groups at the pyridinium rings. All these structural features play an important role in biological activity of these compounds performed by their acute toxicity as well as by their reactivation potency.

• MeSH
• Acetylcholinesterase metabolism   MeSH
• Mice MeSH
• Cholinesterase Reactivators administration & dosage   chemistry   toxicity   MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Cholinesterase Reactivators MeSH