scholarly journals Inhibition of microsomal oxidation of ethanol by pyrazole and 4-methylpyrazole in vitro Increased effectiveness after induction by pyrazole and 4-methylpyrazole

1986 ◽  
Vol 239 (3) ◽  
pp. 671-677 ◽  
Author(s):  
D E Feierman ◽  
A I Cederbaum
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Oxidation ◽  
Liver Microsomes ◽  
Chronic Ethanol ◽  
Ethanol Metabolism ◽  
Ethanol Treatment ◽  
Previously Treated ◽  
Kinetics Of ◽  
Oxidation Of Ethanol

Pyrazole and 4-methylpyrazole, which are inhibitors of alcohol dehydrogenase, were also found to be effective inhibitors of the oxidation of ethanol by liver microsomes (microsomal fractions) in vitro. Ethanol oxidation by microsomes from rats previously treated for 2 or 3 days with either pyrazole or 4-methylpyrazole appeared to be especially sensitive to inhibition in vitro by pyrazole or 4-methylpyrazole. The kinetics of inhibition by pyrazole or 4-methylpyrazole in all microsomal preparations were mixed, as the Km for ethanol was elevated while Vmax was lowered. However, Ki values for pyrazole (about 0.35 mM) and especially 4-methylpyrazole (about 0.03-0.10 mM) were much lower than those found with the saline controls (about 0.7-1.1 mM). In contrast, Ki values for dimethyl sulphoxide as an inhibitor of microsomal ethanol oxidation were similar in all microsomal preparations. Pyrazole and 4-methylpyrazole reacted with microsomes to produce type II spectral changes whose magnitude increased after treatment with either pyrazole or 4-methylpyrazole. Thus the increased inhibitory effectiveness of pyrazole and 4-methylpyrazole appears to be associated with increased interactions with the cytochrome P-450 isoenzyme(s) induced by these compounds. These isoenzymes have properties similar to those of the isoenzyme induced by chronic ethanol treatment. Therefore, caution is needed in the use of pyrazole or 4-methylpyrazole to assess pathways of ethanol metabolism, especially after chronic ethanol treatment, since these agents, besides inhibiting alcohol dehydrogenase, are also effective inhibitors of microsomal ethanol oxidation.

scholarly journals ВПЛИВ ЗАМІЩЕННОГО НІКОТИНАМІДУ ТА ЙОГО МОЖЛИВИХ МЕТАБОЛІТІВ НА АКТИВНІСТЬ ФЕРМЕНТІВ ОБМІНУ ЕТАНОЛУ

2020 ◽  
Vol 144 (2) ◽  
pp. 98-104
Author(s):  
О. В. Кислова
Keyword(s):  
Alcohol Dehydrogenase ◽  
Aldehyde Dehydrogenase ◽  
Ethanol Oxidation ◽  
The Body ◽  
Inhibition Constant ◽  
Ethanol Metabolism ◽  
Dehydrogenase Reaction ◽  
Metabolism Enzymes

To study the influence of N-phenyl-N-(1-cyclopropylethyl)nicotinamide and its possible metabolites: hydrochlorides of N-(1-cyclopropylethyl)amine and N-phenyl-N-(1-cyclopropylethyl)amine - on the activity of  main ethanol oxidation enzymes in vitro and kinetic nature of their interaction. The studies were carried out using alcohol dehydrogenase and aldehyde dehydrogenase of rat liver subcellular fractions, which were obtained by differential centrifugation. The enzyme activity was determined spectrophotometrically. The kinetic nature of alcohol dehydrogenase and isozyme form of aldehyde dehydrogenase  interaction with substituted nicotinamide was investigated in the concentration range of 25-100 μM. The research results were processed by the Lineweaver-Burk method. Studies have shown that N-phenyl-N-(1-cyclopropylethyl)nicotinamide is able to reduce the rate of the reverse alcohol dehydrogenase reaction of acetaldehyde reduction to ethanol in the presence of NADH by 46% with an inhibition constant 53 μM. The activity of soluble mitochondrial aldehyde dehydrogenase was suppressed by 50% with an inhibition constant 108 μM. The kinetic nature of the substituted nicotinamide interaction with enzymes at saturating concentrations of the reaction cofactors NADH and NAD+ is quite complex. Allosteric effects can play a significant role in enzymatic activity. Possible metabolites of the compound - hydrochlorides of N-(1-cyclopropylethyl)- and N-phenyl-N-(1-cyclopropylethyl)amine – didn`t significantly influence on ethanol metabolism enzymes activity. A new inhibitor of the rate of the reverse alcohol dehydrogenase reaction and the activity of soluble mitochondrial isozyme form of aldehyde dehydrogenase, which lead to the accumulation of acetaldehyde in the body, has been discovered. N-phenyl-N-(1-cyclopropylethyl)nicotinamide can be used as a potential antialcohol sensitizing drug after research in vivo.

Kinetics of Alcohol Dehydrogenase-Catalyzed Oxidation of Ethanol Followed by Visible Spectroscopy

2005 ◽  
Vol 82 (7) ◽  
pp. 1068 ◽  
Author(s):  
Kestutis Bendinskas ◽  
Christopher DiJiacomo ◽  
Allison Krill ◽  
Ed Vitz
Keyword(s):  
Alcohol Dehydrogenase ◽  
Visible Spectroscopy ◽  
Kinetics Of ◽  
Catalyzed Oxidation ◽  
Oxidation Of Ethanol

Regulation of ethanol metabolism in the rat

1987 ◽  
Vol 65 (5) ◽  
pp. 458-466 ◽  
Author(s):  
S. Cheema-Dhadli ◽  
F. A. Halperin ◽  
K. Sonnenberg ◽  
V. MacMillan ◽  
M. L. Halperin
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Oxidation ◽  
Maximum Velocity ◽  
Reducing Power ◽  
Ammonium Bicarbonate ◽  
Ethanol Metabolism ◽  
Urea Synthesis ◽  
Major Pathway ◽  
Nadh Generation

The purpose of these experiments was to examine the factors which regulate ethanol metabolism in vivo. Since the major pathway for ethanol removal requires flux through hepatic alcohol dehydrogenase, the activity of this enzyme was measured and found to be 2.9 μmol/(min∙g liver). Ethanol disappearance was linear for over 120 min in vivo and the blood ethanol fell 0.1 mM/min; this is equivalent to removing 20 μmol ethanol/min and would require that flux through alcohol dehydrogenase be about 60% of its measured maximum velocity. To test whether ethanol metabolism was limited by the rate of removal of one of the end products (NADH) of alcohol dehydrogenase, fluoropyruvate was infused to reoxidize hepatic NADH and to prevent NADH generation via flux through pyruvate dehydrogenase. There was no change in the rate of ethanol clearance when fluoropyruvate was metabolized. Furthermore, enhancing endogenous hepatic NADH oxidation by increasing the rate of urea synthesis (converting ammonium bicarbonate to urea) did not augment the steady-state rate of ethanol oxidation. Hence, transport of cytoplasmic reducing power from NADH into the mitochondria was not rate limiting for ethanol oxidation. In contrast, ethanol oxidation at the earliest time periods could be augmented by increasing hepatic urea synthesis.

scholarly journals Mycofactocin Is Associated with Ethanol Metabolism in Mycobacteria

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Gopinath Krishnamoorthy ◽  
Peggy Kaiser ◽  
Laura Lozza ◽  
Karin Hahnke ◽  
Hans-Joachim Mollenkopf ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Treatment Options ◽  
Physiological Role ◽  
Acetic Acid Bacteria ◽  
Ethanol Metabolism ◽  
Ethanol Treatment ◽  
Primary Alcohols ◽  
Poor Growth ◽  
Content Type

ABSTRACTMycofactocin (MFT) belongs to the class of ribosomally synthesized and posttranslationally modified peptides conserved in manyActinobacteria.Mycobacterium tuberculosisassimilates cholesterol during chronic infection, and itsin vitrogrowth in the presence of cholesterol requires most of the MFT biosynthesis genes (mftA,mftB,mftC,mftD,mftE, andmftF), although the reasons for this requirement remain unclear. To identify the function of MFT, we characterized MFT biosynthesis mutants constructed inMycobacterium smegmatis,M. marinum, andM. tuberculosis. We found that the growth deficit ofmftdeletion mutants in medium containing cholesterol—a phenotypic basis for gene essentiality prediction—depends on ethanol, a solvent used to solubilize cholesterol. Furthermore, functionality of MFT was strictly required for growth of free-living mycobacteria in ethanol and other primary alcohols. Among other genes encoding predicted MFT-associated dehydrogenases,MSMEG_6242was indispensable forM. smegmatisethanol assimilation, suggesting that it is a candidate catalytic interactor with MFT. Despite being a poor growth substrate, ethanol treatment resulted in a reductive cellular state with NADH accumulation inM. tuberculosis. During ethanol treatment,mftCmutant expressed the transcriptional signatures that are characteristic of respirational dysfunction and a redox-imbalanced cellular state. Counterintuitively, there were no differences in cellular bioenergetics and redox parameters inmftCmutant cells treated with ethanol. Therefore, further understanding of the function of MFT in ethanol metabolism is required to identify the cause of growth retardation of MFT mutants in cholesterol. Nevertheless, our results establish the physiological role of MFT and also provide new insights into the specific functions of MFT homologs in other actinobacterial systems.IMPORTANCETuberculosis is caused byMycobacterium tuberculosis, and the increasing emergence of multidrug-resistant strains renders current treatment options ineffective. Although new antimycobacterial drugs are urgently required, their successful development often relies on complete understanding of the metabolic pathways—e.g., cholesterol assimilation—that are critical for persistence and for pathogenesis ofM. tuberculosis. In this regard, mycofactocin (MFT) function appears to be important because its biosynthesis genes are predicted to be essential forM. tuberculosisin vitrogrowth in cholesterol. In determining the metabolic basis of this genetic requirement, our results unexpectedly revealed the essential function of MFT in ethanol metabolism. The metabolic dysfunction thereof was found to affect the mycobacterial growth in cholesterol which is solubilized by ethanol. This knowledge is fundamental in recognizing the bona fide function of MFT, which likely resembles the pyrroloquinoline quinone-dependent ethanol oxidation in acetic acid bacteria exploited for industrial production of vinegar.

Ethanol metabolism by the rat heart and alcohol dehydrogenase activity

1976 ◽  
Vol 54 (6) ◽  
pp. 539-545 ◽  
Author(s):  
G. W. Forsyth ◽  
H. T. Nagasawa ◽  
C. S. Alexander
Keyword(s):  
Alcohol Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Rat Heart ◽  
Specific Activity ◽  
Ph Dependence ◽  
Ethanol Metabolism ◽  
Minor Role ◽  
Alcohol Dehydrogenase Activity ◽  
A Minor

Rat hearts perfused with oxygenated buffer containing [1-14C]ethanol metabolized small amounts of the ethanol to carbon dioxide. Very sensitive techniques are required to separate the resulting 14CO2 from the ethanol. This metabolism is not inhibited by levels of pyrazole which markedly inhibit NAD dependent liver alcohol dehydrogenase (EC 1.1.1.1). In vitro studies suggest that NADP functions as a cofactor for the rat heart alcohol dehydrogenase activity of crude heart homogenates. The kinetic parameters, the specific activity, and the pH dependence of the enzyme activity measured in these experiments suggest that it may have a minor role in ethanol metabolism by the rat.

Biochemical aspects of the interaction of ethanol with barbiturates

1970 ◽  
Vol 48 (6) ◽  
pp. 706-711 ◽  
Author(s):  
H. Locksley Trenholm ◽  
William B. Maxwell ◽  
Charles J. Paul ◽  
G. Stuart Wiberg ◽  
Blake B. Coldwell
Keyword(s):  
Alcohol Dehydrogenase ◽  
Enzymatic Activity ◽  
Ammonium Sulfate ◽  
Hepatic Tissue ◽  
Alcohol Metabolism ◽  
Ammonium Sulfate Precipitation ◽  
Tissue Slices ◽  
Catalyzed Oxidation ◽  
Oxidation Of Ethanol

When pentobarbital is added to a hepatic supernatant enzyme fraction which contains alcohol dehydrogenase from a rat, the rates of the enzyme-catalyzed oxidation of ethanol and reduction of acetaldehyde are increased. The pentobarbital enhancement of enzymatic activity which is dependent on pentobarbital concentration is still observed when the enzyme is purified by column chromatography on DEAE- and CM-Sephadex and ammonium sulfate precipitation. In in vitro studies where hepatic tissue slices were incubated with alcohol, pentobarbital inhibited the metabolism of alcohol and increased the acetaldehyde levels in the incubation mixture. The addition of 32.5 mM NAD resulted in a return of alcohol metabolism and acetaldehyde concentrations to control levels.

scholarly journals Hydroxyl-radical production and ethanol oxidation by liver microsomes isolated from ethanol-treated rats

1986 ◽  
Vol 233 (3) ◽  
pp. 755-761 ◽  
Author(s):  
G Ekström ◽  
T Cronholm ◽  
M Ingelman-Sundberg
Keyword(s):  
Amino Acid ◽  
Hydroxyl Radical ◽  
Ethanol Oxidation ◽  
Liver Microsomes ◽  
Radical Scavenger ◽  
Ethanol Treatment ◽  
Radical Production ◽  
Apparent Homogeneity ◽  
Nadph Oxidation ◽  
Cytochrome P 450

In order to distinguish between the mechanism of microsomal ethanol oxidation and hydroxyl-radical formation, the rate of cytochrome P-450 (P-450)-dependent oxidation of dimethyl sulphoxide (Me2SO) was determined in the presence and in the absence of iron-chelating compounds, in liver microsomes from control, ethanol- and phenobarbital-treated rats. Ethanol treatment resulted in a specific increase (3-fold) of the microsomal ethanol oxidation and NADPH consumption per nmol of P-450. A form of P-450 was purified to apparent homogeneity from the ethanol-treated rats and characterized with respect of amino acid composition and N-terminal amino acid sequence. Specific ethanol induction of a cytochrome P-450 species having a catalytic-centre activity of 20/min for ethanol and consuming 30 nmol of NADPH/min could account for the results observed with microsomes. Phenobarbital treatment caused 50% decrease in the rate of ethanol oxidation and NADPH oxidation per nmol of P-450. The rate of oxidation of the hydroxyl-radical scavenger Me2SO was increased 3-fold by ethanol or phenobarbital treatment when expressed on a per-mg-of-microsomal-protein basis, but the rate of Me2SO oxidation expressed on a per-nmol-of-P-450 basis was unchanged. Addition of iron-chelating agents to the three different types of microsomal preparations caused an ‘uncoupling’ of the electron-transport chain accompanied by a 4-fold increase of the rate of Me2SO oxidation. It is concluded that ethanol treatment results in the induction of P-450 forms specifically effective in ethanol oxidation and NADPH oxidation, but not in hydroxyl-radical production, as detected by the oxidation of Me2SO.

scholarly journals Effect of chronic ethanol treatment in vivo on excitability in mouse cortical neurones in vitro

1997 ◽  
Vol 122 (5) ◽  
pp. 956-962 ◽  
Author(s):  
T. Ibbotson ◽  
M. J. Field ◽  
P. R. Boden
Keyword(s):  
Chronic Ethanol ◽  
Ethanol Treatment

scholarly journals In vitro evaluation of Álcool desidrogenase kinetics in Ziziphus joazeiro fruits to alleviate the harmful effects of alcohol

2020 ◽  
Vol 9 (4) ◽  
pp. e107942900
Author(s):  
Alvaro Gustavo Ferreira da Silva ◽  
Franciscleudo Bezerra da Costa ◽  
Yasmin Lima Brasil ◽  
Brencarla de Medeiros Lima ◽  
Eder Pereira da Rocha Sousa ◽  
...  
Keyword(s):  
Room Temperature ◽  
Food Supplement ◽  
The Body ◽  
Ethanol Metabolism ◽  
Maturation Stage ◽  
Alcohol Metabolism ◽  
Kinetics Of ◽  
Adh Activity ◽  
Harmful Effects

Ziziphus joazeiro is endemic to the brazilian Caatinga and its fruits can be used as a food supplement by accelerating the ethanol metabolism in the body and reducing the alcohol harmful effects due to high alcohol dehydrogenase (ADH) activity. The objective was to determine the kinetics of ADH activity, in different incubation times, of Z. joazeiro mature fruits as a food supplement. Ziziphus joazeiro fruits, at the fourth maturation stage, were incubated for 0 (no incubation), 3, 6, 12, 24 and 48 hours at room temperature. The ADH activity was determined. ADH activity was higher in fruits incubated for 0 and 3 h. The ADH activity was higher in the early incubation times, probably due to the greater availability of NAD+, which after being reduced to NADH delayed regeneration. Without the cofactor in the oxidized form, the enzymatic activity decreases. Ziziphus joazeiro fruit has the potential to be used as a food supplement accelerating the alcohol metabolism and reducing the harmful effects.

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