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In this work in vitro evaluation of the reactivation potency of the newly synthesized reactivators for acetylcholinesterase (AChE; EC 3.1.1.7) is described. Using this method, reactivation potency of 21 potential reactivators of AChE inhibited by the nerve agent sarin has been evaluated. We have confirmed the fact that currently the most promising AChE reactivator, HI-6, is the most effective reactivator of sarin-inhibited AChE. There are only three AChE reactivators—HI-6, TO033 and TO047—able to satisfactorily reactivate sarin-inhibited AChE at the concentration 10 -5 M, which is nontoxic for human use. On the other hand, there are 14 AChE reactivators, that are able to reactivate sarin-inhibited AChE at the concentration 10 -3 M. However, this concentration of reactivator is probably toxic for human use. [ABSTRACT FROM AUTHOR]

The efficacy of various oximes to reactivate acetylcholinesterase phosphorylated by tabun (O-ethyl-N,N-dimethyl phosphoramidocyanidate) was tested byin vitroandin vivomethods. The oximes commonly used for the treatment of acute poisonings with highly toxic organophosphates appeared to be almost ineffective (HI-6, pralidoxime, methoxime) or just slightly effective (obidoxime) against tabun. On the other hand, trimedoxime seemed to be a significantly more efficacious reactivator than the others in the case of tabun poisonings.In vitro, the concentration of trimedoxime corresponding to 1.0 mmol/l was able to reach 50% reactivation of tabun-inhibited brain acetylcholinesterase. Higher reactivating potency of trimedoxime in comparison with the other commonly used oximes was demonstrated byin vivomethod, too. In addition, other structural analogues of trimedoxime were found to be efficacious in counteracting tabun-induced acetylcholinesterase inhibition although not as efficacious as trimedoxime itself. Some effective acetylcholinesterase reactivators were characterised by dissociation constant of enzyme-reactivator complex as well as enzyme-inhibitor-reactivator complex and by rate constant of reactivation. [ABSTRACT FROM AUTHOR]