Limitation of the Ellman method: Cholinesterase activity measurement in the presence of oximes

Šinko, Goran; Čalić, Maja; Bosak, Anita; Kovarik, Zrinka

doi:10.1016/j.ab.2007.07.023

Cited by 103 publications

(61 citation statements)

References 13 publications

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“…The fi nal plasma dilution in the experiments was 200 to 300 fold, while the fi nal dilution of erythrocytes was 400 fold. Final oxime and ATCh concentrations used in the experiments, stated in Table 1, were chosen so that the oxime induced ATCh hydrolysis did not interfere with the studied interactions (21,22).…”

Section: Cholinesterases and Activity Measurementmentioning

confidence: 99%

Evaluation of Oxime K203 as Antidote in Tabun Poisoning

Kovarik

Vrdoljak

Berend

et al. 2009

Archives of Industrial Hygiene and Toxicology

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We studied bispyridinium oxime K203 [(E)-1-(4-carbamoylpyridinium)-4-(4-hydroxyimino methylpyridinium)-but-2-ene dibromide] with tabun-inhibited human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in vitro, and its antidotal effect on tabun-poisoned mice and rats in vivo. We compared it with oximes K048 and TMB-4, which have proven the most effi cient oxime antidotes in tabun poisoning by now. Tabun-inhibited AChE was completely reactivated by K203, with the overall reactivation rate constant of 1806 L mol -1 min -1 . This means that K203 is a very potent reactivator of tabun-inhibited AChE. In addition, K203 reversibly inhibited AChE (K i = 0.090 mmol L ), and exhibited its protective effect against phosphorylation of AChE by tabun in vitro. In vivo, a quarter of the LD 50 K203 dose insured survival of all mice after the application of as many as 8 LD 50 doses of tabun, which is the highest dosage obtained compared to K048 and TMB-4. Moreover, K203 showed high therapeutic potency in tabun-poisoned rats, preserving cholinesterase activity in rat plasma up to 60 min after poisoning. This therapeutic improvement obtained by K203 in tabun-poisoning places this oxime in the spotlight for further development.

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Section: Cholinesterases and Activity Measurementmentioning

confidence: 99%

Evaluation of Oxime K203 as Antidote in Tabun Poisoning

Kovarik

Vrdoljak

Berend

et al. 2009

Archives of Industrial Hygiene and Toxicology

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“…On the other hand, their efficacy is limited by the safe dosage and this constrains their reactivation efficacy [17]. Hence, the measured AChE activity might appear higher than the real AChE activity due to oximolysis [18]. The efficacy of the reactivators used to recover the blood AChE activity is presented in Figure 2A.…”

Section: Resultsmentioning

confidence: 99%

Changes of rat plasma total low molecular weight antioxidant level after tabun exposure and consequent treatment by acetylcholinesterase reactivators

Pohanka

Karasová

Musílek

et al. 2010

Journal of Enzyme Inhibition and Medicinal Chemistry

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“…3) was also used to identify OP exposure, as well as detoxification by the OP antidotes (while acetylcholinesterase (3.1.1.7) can be determined from whole blood, when plasma is analyzed, we measure butyrylcholinesterase (3.1.1.8) activity with acetylthiocholine as a substrate). It has to be noted that oximes, such as 2-PAM, can react with acetylthiocholine (oximolysis), producing thiocholine that can react with the thiol reagent 5,5′-dithio-bis-2-nitrobenzoic acid of the Ellman's method (34)(35)(36). This suggests that the Ellman method has to be employed critically in the presence of oximes: if the reaction of oximolysis is faster than the Ellman reaction under the experimental conditions, then the observed 5-thio-2-nitrobenzoic acid concentration can originate from both the cholinesterase reaction and the oximolysis of acetylthiocholine.…”

Section: Discussionmentioning

confidence: 99%

Nano-Intercalated Organophosphorus-Hydrolyzing Enzymes in Organophosphorus Antagonism

et al. 2011

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Abstract. A dendritic poly(2-alkyloxazoline)-based polymer was studied as a new carrier system for the organophosphorus-hydrolyzing recombinant enzymes, organophosphorus acid anhydrolase and organophosphorus hydrolase. Paraoxon (PO) and diisopropylfluorophosphate (DFP) were used as model organophosphorus compounds. Changes in plasma cholinesterase activity were monitored. The cholinesterase activity was proportional to the concentrations of DFP or PO. Plasma cholinesterase activity was higher in animals receiving enzyme and oxime before the organophosphates than in the oxime-only pretreated groups. These studies suggest that cholinesterase activity can serve as an indicator for the in vivo protection by the nano-intercalated organophosphorus acid anhydrolase or organophosphorus hydrolase against organophosphorus intoxications. These studies represent a practical application of polymeric nano-delivery systems as enzyme carriers in drug antidotal therapy.KEY WORDS: dendritic polymer; diisopropylfluorophosphate (DFP); organophosphorus acid anhydrolase (OPAA); paraoxon; 2-PAM.

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Limitation of the Ellman method: Cholinesterase activity measurement in the presence of oximes

Cited by 103 publications

References 13 publications

Evaluation of Oxime K203 as Antidote in Tabun Poisoning

Evaluation of Oxime K203 as Antidote in Tabun Poisoning

Changes of rat plasma total low molecular weight antioxidant level after tabun exposure and consequent treatment by acetylcholinesterase reactivators

Nano-Intercalated Organophosphorus-Hydrolyzing Enzymes in Organophosphorus Antagonism

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