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

2013 ◽  
Vol 68 (3-4) ◽  
pp. 133-138 ◽  
Author(s):  
Markéta Kovářováa ◽  
Karel Komersa ◽  
Šárka Štěpánková ◽  
Patrik Pařík ◽  
Alexander Čegan
Keyword(s):  
Time Course ◽  
Cholinesterase Inhibitors ◽  
Ph Value ◽  
Batch Reactor ◽  
Measuring Cell ◽  
Inhibition Concentration ◽  
Different Types ◽  
Ph Stat ◽  
Hydrolysis Of

A new and simple analytical method is described for the determination of the IC50 values of the inhibitors of the hydrolysis of acetylcholine (ACh) or acetylthiocholine (ATCh) by cholinesterases. The method is based on monitoring the time course of the pH value during the uninhibited and inhibited reaction. It requires only a pH meter with a suitable pH measuring cell and a small thermostated stirred batch reactor. The method has been validated for twelve different types of cholinesterase inhibitors. The determined IC50 values are comparable to those obtained by independent, more complicated, and expensive methods (Ellman´s and pH-stat).

scholarly journals Kinetics and Mechanism of Hydrolysis of Acetylthiocholine by Butyrylcholine Esterase

2002 ◽  
Vol 57 (11-12) ◽  
pp. 1072-1077 ◽  
Author(s):  
Karel Komers ◽  
Alexandr Čegan ◽  
Marek Link
Keyword(s):  
Acetic Acid ◽  
Kinetics And Mechanism ◽  
Kinetics Parameters ◽  
Mechanism Of Hydrolysis ◽  
Ph Stat ◽  
Stat Method ◽  
Ellman’S Method ◽  
Hydrolysis Of

Kinetics and mechanism of hydrolysis of acetylthiocholine by the enzyme butyrylcholine esterase was studied. The spectrophotometric Ellman’s method and potentiometric pH-stat method were used for continuous determination of the actual concentration of the products thiocholine and acetic acid in the reaction mixture. The validity of the Michaelis-Menten (Briggs-Haldane) equation in the whole course of the reaction under used conditions was proved. The corresponding kinetics parameters (Vm and KM) were calculated from the obtained dependences of concentration of thiocholine or acetic acid vs. time and compared. From this comparison the deciding kinetic role of the step producing thiocholine was derived. The values of initial molar concentration of the enzyme and of the rate constants of the kinetic model were estimated.

scholarly journals The hydrolysis of glycosyl fluorides by glycosidases. Determination of the anomeric configuration of the products of glycosidase action

1971 ◽  
Vol 123 (4) ◽  
pp. 607-611 ◽  
Author(s):  
J. E. G. Barnett
Keyword(s):  
Glucose Oxidase ◽  
Galactose Oxidase ◽  
Coffee Bean ◽  
Enzymic Hydrolysis ◽  
Initial Product ◽  
Rapid Assay ◽  
Anomeric Configuration ◽  
Ph Stat ◽  
Hydrolysis Of

The enzymic hydrolysis of glycosyl fluorides is conveniently followed by using a pH-stat. Reactions involving glucosyl or galactosyl fluorides can also be followed by using glucose oxidase or galactose oxidase respectively. The pH-stat allows the rapid assay of intestinal α-glucosidase in crude homogenates. Use of glycosyl fluorides as substrates for glycosidases facilitates the polarimetric or g.l.c. determination of the anomeric nature of the initial product of hydrolysis. Hydrolysis by fungal amyloglucosidase proceeds with inversion of configuration whereas that by yeast and rat intestinal α-glucosidase, coffee-bean α-galactosidase and almond emulsin β-glucosidase proceeds with retention of configuration. β-d-Glucopyranosyl azide was not a detectable substrate for almond emulsin β-d-glucosidase.

Determination of the proportion of κ-casein hydrolysed by rennet on coagulation of skim-milk

1980 ◽  
Vol 47 (3) ◽  
pp. 351-358 ◽  
Author(s):  
Brian Chaplin ◽  
Margaret L. Green
Keyword(s):  
Quantitative Determination ◽  
Gel Electrophoresis ◽  
Time Course ◽  
Polyacrylamide Gel Electrophoresis ◽  
Skim Milk ◽  
Casein Micelle ◽  
Clotting Time ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

SummaryA method has been developed for quantitative determination of para-κ-casein, involving spectrophotometric scanning of stained protein bands following polyacrylamide gel electrophoresis. The rate of hydrolysis of κ-casein in skim-milk at pH 6·6 and 30 °C was compared with that in EDTA-treated skim-milk under the same conditions. This showed that at the visually observed clotting time, at least 90% of the total κ-casein in milk had been hydrolysed. The time course of the reaction was consistent with all the κ-casein molecules being hydrolysed with the same efficiency. The results strongly suggest that essentially all of the κ-casein in milk is equally accessible to rennet action. This is consistent with the casein micelle being porous, or having all the κ-casein on the surface.

scholarly journals Influence of NaCl on the polymerization of vinyl monomers by the suspension process

2019 ◽  
pp. 19-23
Author(s):  
Erika Montero ◽  
David Contreras-López ◽  
Rosalba Fuentes ◽  
María Del Rosario Galindo
Keyword(s):  
Batch Reactor ◽  
Research Work ◽  
Chemical Properties ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Suspension Process ◽  
Different Types ◽  
Physical And Chemical ◽  
And Chemical Properties

The production of artificial polymers is, today, one of themost important activities of the chemical industry, polymersare widely used in everyday life, as, there are different types of polymers, they can be used for different uses. These polymeric materials have unique mechanical, physical and chemical properties, which most other materials do not possess, not to mention that its cost is lower than the other materials. The present research work focuses on the determination of optimal operating conditions for the polymerization of styrene and methyl methacrylate in a Batch reactor, as well as the influence of inorganic salt in this case NaCl in the performance of reaction and in the size of the material polymer, through the process of suspension using a synthetic route of polymerization by radical free conventional (FRP), where viscometry to the polymeric material testing was performed for this way characterize it, and to determine factors of interest such as the molecular weight, etc.

scholarly journals Determination of appropriate level of fat in milk for the production of good quality dahi

2016 ◽  
Vol 2 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Morsheda Yesmin ◽  
Md Rezaul Hai Rakib ◽  
Al Amin Hossain ◽  
Akhi Khan ◽  
Md Nurul Islam
Keyword(s):  
Quality Assessment ◽  
Milk Fat ◽  
Economic Benefit ◽  
Ph Value ◽  
Ash Content ◽  
Assessment Tests ◽  
Physical Chemical ◽  
Different Types ◽  
Organoleptic Parameters

The research was conducted to determine the approximate fat in milk for good quality dahi production and to inform dahi manufacturers’ about the acceptable level of milk fat to be used and also their economic benefit. Quality assessment tests were conducted on four different types of dahi prepared by adding different percentage of milk fat such as 3.5% (A), 4.0% (B), 4.5% (C) and 5.0% (D) respectively. All the samples were analyzed for organoleptic, chemical and microbiological qualities. The scores for smell and taste, body and texture, color and appearance, and total scores for four types of dahi samples showed significant differences at various levels (p<0.01 to p<0.05). It was found that scores for all the organoleptic parameters of sample C were the highest among the samples, whereas sample A obtained the lowest scores. Smell and taste, body and texture, total score, TS content, water content, fat content and coliform count were differed significantly (P<0.01). Color and appearance, protein content and % acidity also showed significant differences (P<0.05), though CHO content, ash content and pH value showed insignificant differences. It could be concluded that sample C (containing 4.5% milk fat) was the best in terms of physical, chemical and microbiological qualities.Asian J. Med. Biol. Res. June 2016, 2(2): 253-258

scholarly journals Assay of Poly(3-Hydroxybutyrate) Depolymerase Activity and Product Determination

2006 ◽  
Vol 72 (9) ◽  
pp. 6094-6100 ◽  
Author(s):  
Birgit Gebauer ◽  
Dieter Jendrossek
Keyword(s):  
High Performance ◽  
Ralstonia Eutropha ◽  
Hydrolysis Product ◽  
Hydrolysis Rates ◽  
Product Identification ◽  
Consumption Rates ◽  
Ph Stat ◽  
First Time ◽  
Hydrolysis Of

ABSTRACT Two methods for accurate poly(3-hydroxybutyrate) (PHB) depolymerase activity determination and quantitative and qualitative hydrolysis product determination are described. The first method is based on online determination of NaOH consumption rates necessary to neutralize 3-hydroxybutyric acid (3HB) and/or 3HB oligomers produced during the hydrolysis reaction and requires a pH-stat apparatus equipped with a software-controlled microliter pump for rapid and accurate titration. The method is universally suitable for hydrolysis of any type of polyhydroxyalkanoate or other molecules with hydrolyzable ester bonds, allows the determination of hydrolysis rates of as low as 1 nmol/min, and has a dynamic capacity of at least 6 orders of magnitude. By applying this method, specific hydrolysis rates of native PHB granules isolated from Ralstonia eutropha H16 were determined for the first time. The second method was developed for hydrolysis product identification and is based on the derivatization of 3HB oligomers into bromophenacyl derivates and separation by high-performance liquid chromatography. The method allows the separation and quantification of 3HB and 3HB oligomers up to the octamer. The two methods were applied to investigate the hydrolysis of different types of PHB by selected PHB depolymerases.

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

2013 ◽  
Vol 68 ◽  
pp. 0133
Author(s):  
Marketa Kovarova ◽  
Karel Komers ◽  
Sárka Stepánkova ◽  
Patrik Parík ◽  
Alexander Cegan
Keyword(s):  
Cholinesterase Inhibitors ◽  
New Method ◽  
Inhibition Concentration

scholarly journals Secondary Metabolites Identification and Antioxidant Activity Determination of Crude Extract of Barringtonia asiatica l. (kurz) Leaves

2021 ◽  
pp. 51-58
Author(s):  
Rega Permana ◽  
Aulia Andhikawati
Keyword(s):  
Antioxidant Activity ◽  
Methanol Extract ◽  
Geographic Region ◽  
Activity Profile ◽  
West Java ◽  
Inhibition Concentration ◽  
Ic50 Value ◽  
Different Types ◽  
Phytochemical Constituent

Aims: The aims of this study were to elucidate the pythochemical compounds from the leaf of mangrove (Barringtonia asiatica L. (Kurz) colleceted from the coast of Pangandaran Regency, West Java, Indonesia as well as its antioxidant activity profile. Study Design: The study was designed experimentally with two replication (duplo) for the extraction preparation and analyzed statistically using regression linear for the determination of Inhibition Concentration at 50% or IC50. Place and Duration of Study: Sample were collected from the mangrove ecotourism site at Pangandaran Regency, West Java, Indonesia. The experimental study was performed at the Tropical Marine and Fisheries Laboratory, Fisheries Department, PSDKU Padjadjaran University, Indonesia. Methodology: The identification of pythochemical contents of the leaf was carried out qualitatively with the principle of formation of precipitate, color and foam. The extraction was performed accordingly using three different types of solvent, n-hexane, ethyl acetate and methanol. Lastly, the antioxidant activity was tested using DPPH (1,-diphenyl-2-picrylhydrazyl) method and IC50 were analyzed subsequently. Results: Based on the results of the research that has been carried out, it can be concluded that the leaves of Barringtonia asiatica L. (Kurz) contain bioactive compounds in the form of tannins and saponins. The methanol extract of Barringtonia asiatica L. (Kurz)  was proven to have moderate strength antioxidant activity with IC50 value of 125.87 ppm. Conclusion: this results concluded that different geographic region can influence the phytochemical constituent of the of Barringtonia asiatica L. (Kurz). Furthermore, this doesn’t hindered its antioxidant activity potential as it still proven to have a relatively medium antioxidant activity.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

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