Half-inhibition Concentrations of New Cholinesterase Inhibitors

Zdražilová, Pavla; Štěpánková, Šárka; Komers, Karel; Ventura, Karel; Cegan, Alexander

doi:10.1515/znc-2004-3-430

Cited by 36 publications

(27 citation statements)

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“…Some values of pI 50 in Table I, determined by Ellman´s method, can be compared with those published: sevin, pI 50 = 4.33 (Kulhavý et al, 2002) and 4.11 (Pavlová, 1998); rivastigmine (Exelon), 3.3 (Zdražilová et al, 2004(Zdražilová et al, , 2006b); galanthamine (Reminyl), 3.26 (Štěpánková et al, 2007); imidazoles I1, 4.56, and I2, 4.61 (Kovářová et al, 2010).…”

Section: Resultsmentioning

confidence: 93%

“…Ellman´s method (Ellman et al, 1961) is routinely used for the determination of the cholinesterase activity and effi ciency of cholinesterase inhibitors. It is based on the measurement of the absorbance at 412 nm of the yellow complex produced by the reaction between thiocholine (TCh) and DTNB (5,5´-dithiobis-2-nitrobenzoic acid, Ellman´s reagent), as described in detail in Zdražilová et al (2004). Ellman´s method has two disadvantages: 1) The composition of the yellow complex and its absorption coeffi cient at 412 nm depend strongly on the composition of the reaction mixture, above all on the pH value.…”

Section: Introductionmentioning

confidence: 99%

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New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors

Kovarova

Komers²,

Štěpánková³

et al. 2013

Zeitschrift Für Naturforschung C

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IntroductionThe IC 50 is the molar concentration of a given inhibitor (I), which reduces the respective uninhibited reaction rate to one half, and is indicative of the inhibitory potency of a compound. We investigated new inhibitors of the in vitro hydrolysis of acetylcholine (ACh) by cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Ellman´s method (Ellman et al., 1961) is routinely used for the determination of the cholinesterase activity and effi ciency of cholinesterase inhibitors. It is based on the measurement of the absorbance at 412 nm of the yellow complex produced by the reaction between thiocholine (TCh) and DTNB (5,5´-dithiobis-2-nitrobenzoic acid, Ellman´s reagent), as described in detail in Zdražilová et al. (2004). Ellman´s method has two disadvantages: 1) The composition of the yellow complex and its absorption coeffi cient at 412 nm depend strongly on the composition of the reaction mixture, above all on the pH value. 2) Acetylthiocholine (ATCh) instead of ACh must be used as the substrate. However, the reaction rates of the ACh and ATCh hydrolysis by AChE (or BChE) are not identical, nor are the IC 50 values (Zdražilová et al., 2006a).When using ACh, the determination of the rate of the enzymatic reaction, and hence also of IC 50 , requires the quantitative determination of the concentration of one of the reaction components, i.e. ACh, choline (Ch), acetic acid (HAc), or protons from HAc, in the reaction mixture. The suitable methods, e.g. HPLC or pH-stat (Zdražilová et al., 2006b), are experimentally much more sophisticated and time-consuming. This paper describes a new simple, and fast method of IC 50 determination with the possibility of using either ACh or ATCh. The method is based on the measurement of changes in the pH value as a function of time during the enzymatic hydrolysis of ACh or ATCh, it is called the pH(t) method. Material and Methods Principle of the pH(t) methodDuring the enzymatic hydrolysis of ACh (ATCh) by cholinesterases HAc is formed. Therefore, in a non-buffered reaction mixture the pH value decreases in time according to the kinetics of the hydrolysis and dissociation constant of the weak acid HAc in aqueous milieu. This decrease is slower in the presence of an inhibitor. As a consequence of the pH change of the reaction mixture, the activity of AChE changes continuously. We suppose that the activity changes proportionally during uninhibited and inhibited hydrolyses, respectively. So, by suitable comparison of the time courses of the two hydrolyses, under otherwise identical conditions, this change of activity can be disregarded. Realization of the measurementA pH meter (inoLab, Level 2; WTW, Weinheim, Germany) with a cell glass electrode/saturated silver chloride electrode (6.0234.110; Metrohm, Herisau, Switzerland) was used for the determination of pH(t) in the reaction mixture containing either ACh or ATCh, AChE, with or without inhibitor (I). The following reaction conditions were used: 25 °C; initial molarity, [ACh] 0 = [ATCh] 0 = 4 mM;...

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors

Kovarova

Komers²,

Štěpánková³

et al. 2013

Zeitschrift Für Naturforschung C

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“…The given melting points were not corrected. Structures of the products prepared were 12 The determination of partition coefficient (P ow ) in n-octanol/water system was carried out by a known method. ).…”

Section: Methodsmentioning

confidence: 99%

Substituted benzyl N-phenylcarbamates – their solvolysis and inhibition activity to acetylcholinesterase and butyrylcholinesterase

Sedlák¹,

Hanusek²,

Drabina³

et al. 2009

Arkivoc

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Kinetic evidence has indicated that methanolysis of synthesized 4-acetoxybenzyl carbamates proceeds via a one-step (concerted) mechanism. Concerted 1,6-elimination produces the very reactive 1,4-quinonemethide, which was trapped in the form of 4-methoxymethylphenol. The inhibition activity of benzyl N-phenylcarbamates to acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE) was also tested. The found IC 50 values varied within the limits of 199-535 µmol·l -1 for ACHE and 21-177 µmol·l -1 for BCHE. The found values of partition coefficient (P ow ) in the range of 1.5-11.5 represent a prerequisite of good transport of benzyl Nphenylcarbamates through haemato-encephalic barrier.

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“…graphically from log concentration percent inhibition curves. [21] www.wjpps.com They had free access to water ad-libitum and were fed with semi synthetic balanced diet, with occasional supply of green vegetables (salad leaves). Six rats were housed per cage at temperature (22 ºC ± 3º C) and 45-55% relative humidity.…”

Section: Biological Studies Estimation Of Cholinesterase Activity (Inmentioning

confidence: 99%

Design, Synthesis and Evaluation of Some New 4-Aminobenzoic Acid Derivatives as Potential Cognition Enhancer

Shirsat¹

2017

WJPPS

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A series of new Schiff bases from p-amino benzoic acid has been designed, synthesized and evaluated for cognition enhancing activities through the inhibition of acetylcholinesterase (AChE) and by passive avoidance model. The results illustrated a significant cognition enhancing effect on passive avoidance test with a significant reversal of scopolamine-induced amnesia, which is comparable with standard drug rivastigmine. The in-vitro study of synthesized compounds showed maximum activity of compound-9 compared to standard drug rivastigmine, whereas its enzyme kinetic study revealed a noncompetitive inhibition of acetycholinesterase (AChE), which may be attributed to a possible interaction of compound with the peripheral anionic site (PAS) of AChE and was also confirmed by molecular docking studies.

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Half-inhibition Concentrations of New Cholinesterase Inhibitors

Cited by 36 publications

References 0 publications

New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors

New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors

Substituted benzyl N-phenylcarbamates – their solvolysis and inhibition activity to acetylcholinesterase and butyrylcholinesterase

Design, Synthesis and Evaluation of Some New 4-Aminobenzoic Acid Derivatives as Potential Cognition Enhancer

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Half-inhibition Concentrations of New Cholinesterase Inhibitors

Cited by 36 publications

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New Method for the Determination of the Half Inhibition Concentration (IC50) of Cholinesterase Inhibitors

New Method for the Determination of the Half Inhibition Concentration (IC50) of Cholinesterase Inhibitors

Substituted benzyl N-phenylcarbamates – their solvolysis and inhibition activity to acetylcholinesterase and butyrylcholinesterase

Design, Synthesis and Evaluation of Some New 4-Aminobenzoic Acid Derivatives as Potential Cognition Enhancer

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New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors

New Method for the Determination of the Half Inhibition Concentration (IC₅₀) of Cholinesterase Inhibitors