ANTIOXIDANTS AS INHIBITORS OF LINOLEATE OXIDATION CATALYZED BY PLANT LIPOXIDASE AND BY HEMOLYZATES OF HUMAN ERYTHROCYTES

1955 ◽  
Vol 33 (5) ◽  
pp. 773-779 ◽  
Author(s):  
H. Bruce Collier ◽  
Sheila C. McRae
Keyword(s):  
Fatty Acids ◽  
Catalytic Activity ◽  
Erythrocyte Membrane ◽  
Unsaturated Fatty Acids ◽  
Human Erythrocytes ◽  
Catalytic Action ◽  
Time Activity ◽  
Linoleate Oxidation

Hemolyzates of human erythrocytes catalyzed the oxidation of linoleate at pH 7 but not at pH 9. Hence the erythrocytes contained no lipoxidase and the catalytic action was probably due to hemoglobin. However, the time-activity curves for hemolyzates and for crystalline hemoglobin were not identical in shape. The oxidation of linoleate at pH 7 by plant lipoxidase was powerfully inhibited by phenothiazine and by phenylhydrazine. These compounds, and also α-tocopherol and α-naphthol, inhibited the catalytic activity of hemolyzates and of crystalline hemoglobin. It is probable that phenothiazine and phenylhydrazine act as antioxidants in these systems. Antioxidants in vivo may possibly play a role in protecting the unsaturated fatty acids of the erythrocyte membrane from oxidation catalyzed by hemoglobin.

ANTIOXIDANTS AS INHIBITORS OF LINOLEATE OXIDATION CATALYZED BY PLANT LIPOXIDASE AND BY HEMOLYZATES OF HUMAN ERYTHROCYTES

1955 ◽  
Vol 33 (1) ◽  
pp. 773-779 ◽  
Author(s):  
H. Bruce Collier ◽  
Sheila C. McRae
Keyword(s):  
Fatty Acids ◽  
Catalytic Activity ◽  
Erythrocyte Membrane ◽  
Unsaturated Fatty Acids ◽  
Human Erythrocytes ◽  
Catalytic Action ◽  
Time Activity ◽  
Linoleate Oxidation

Hemolyzates of human erythrocytes catalyzed the oxidation of linoleate at pH 7 but not at pH 9. Hence the erythrocytes contained no lipoxidase and the catalytic action was probably due to hemoglobin. However, the time-activity curves for hemolyzates and for crystalline hemoglobin were not identical in shape. The oxidation of linoleate at pH 7 by plant lipoxidase was powerfully inhibited by phenothiazine and by phenylhydrazine. These compounds, and also α-tocopherol and α-naphthol, inhibited the catalytic activity of hemolyzates and of crystalline hemoglobin. It is probable that phenothiazine and phenylhydrazine act as antioxidants in these systems. Antioxidants in vivo may possibly play a role in protecting the unsaturated fatty acids of the erythrocyte membrane from oxidation catalyzed by hemoglobin.

Membrane incorporation of non-esterified fatty acids and effects on the sodium pump of human erythrocytes

1992 ◽  
Vol 82 (1) ◽  
pp. 99-104 ◽  
Author(s):  
J. F. St. J. Dwight ◽  
A. C. Mendes Ribeiro ◽  
B. M. Hendry
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Stearic Acid ◽  
Erythrocyte Membrane ◽  
Sodium Pump ◽  
Human Erythrocytes ◽  
Pump Function ◽  
Change In Mean ◽  
Oleic And Linoleic Acids

1. Sodium pump function has been assessed by measurement of ouabain-sensitive 86Rb uptake in human erythrocytes after incorporation of palmitic, stearic, oleic and linoleic acids into the erythrocyte membrane. 14C-labelled fatty acids were used to measure membrane uptake of these substances. 2. For palmitic, oleic and linoleic acids, up to 1000 nmol of the fatty acid/ml of packed cells can be incorporated without causing significant haemolysis. For stearic acid, 270 nmol/ml of packed cells was incorporated in similar conditions. More than 88% of the fatty acid incorporated could be extracted with a 50 μmol/l fatty-acid-free albumin solution and was, therefore, in a non-esterified form in the erythrocyte membrane. The concentrations of palmitic, stearic, oleic and linoleic acids incorporated in these experiments represent a five- to ten-fold increase above the normal concentrations of these fatty acids in the membrane. 3. Up to 1000 nmol of palmitic, oleic and linoleic acids/ ml of packed cells and up to 270 nmol of stearic acid/ml of packed cells could be incorporated without a significant change in mean ouabain-sensitive 86Rb uptake with respect to control cells. Mean percentage changes in ouabain-sensitive 86Rb uptake for all these experiments were: palmitic acid, 3.7% (sd 11.4, n = 15); stearic acid, 4.0% (sd 5.7, n = 7); oleic acid, −4.8% (sd 19, n = 17); linoleic acid, 2.2% (sd 15.6, n = 19). 4. The demonstration of near-normal sodium pump activity in the presence of greatly elevated membrane levels of these fatty acids makes it extremely unlikely that they act as modulators of sodium pump function in vivo.

scholarly journals Studies of the long-term regulation of hepatic pyruvate dehydrogenase kinase

1998 ◽  
Vol 329 (1) ◽  
pp. 89-94 ◽  
Author(s):  
C. Mary SUGDEN ◽  
G. D. Lee FRYER ◽  
A. Karen ORFALI ◽  
A. David PRIESTMAN ◽  
Elaine DONALD ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Pyruvate Dehydrogenase ◽  
Unsaturated Fatty Acids ◽  
Fold Increase ◽  
Membrane Lipid ◽  
Dietary Lipid ◽  
Pyruvate Dehydrogenase Kinase ◽  
Plasma Insulin Concentration

The administration of a low-carbohydrate/high-saturated-fat (LC/HF) diet for 28 days or starvation for 48 h both increased pyruvate dehydrogenase kinase (PDHK) activity in extracts of rat hepatic mitochondria, by approx. 2.1-fold and 3.5-fold respectively. ELISAs of extracts of hepatic mitochondria, conducted over a range of pyruvate dehydrogenase (PDH) activities, revealed that mitochondrial immunoreactive PDHKII (the major PDHK isoform in rat liver) was significantly increased by approx. 1.4-fold after 28 days of LC/HF feeding and by approx. 2-fold after 48 h of starvation. The effect of LC/HF feeding to increase hepatic PDHK activity was retained through hepatocyte preparation, but was decreased on 21 h culture with insulin (100μ-i.u./ml). A sustained (24 h) 2-4-fold elevation in plasma insulin concentration in vivo (achieved by insulin infusion via an osmotic pump) suppressed the effect of LC/HF feeding so that hepatic PDHK activities did not differ significantly from those of (insulin-infused) control rats. The increase in hepatic PDHK activity evoked by 28 days of LC/HF feeding was prevented and reversed (within 24 h) by the replacement of 7% of the dietary lipid with long-chain ω-3 fatty acids. Analysis of hepatic membrane lipid revealed a 1.9-fold increase in the ratio of total polyunsaturated ω-3 fatty acids to total mono-unsaturated fatty acids. The results indicate that the increased hepatic PDHK activities observed in livers of LC/HF-fed or 48 h-starved rats are associated with long-term actions to increase hepatic PDHKII concentrations. The long-term regulation of hepatic PDHK by LC/HF feeding might be achieved through an impaired action of insulin to suppress PDHK activity. In addition, the fatty acid composition of the diet, rather than the fat content, is a key influence.

scholarly journals Overlapping Repressor Binding Sites Result in Additive Regulation of Escherichia coli FadH by FadR and ArcA

2010 ◽  
Vol 192 (17) ◽  
pp. 4289-4299 ◽  
Author(s):  
Youjun Feng ◽  
John E. Cronan
Keyword(s):  
Escherichia Coli ◽  
Fatty Acids ◽  
Cyclic Amp ◽  
Unsaturated Fatty Acids ◽  
Genetic Regulation ◽  
Receptor Protein ◽  
Anaerobic Conditions ◽  
Mobility Shift ◽  
Long Chain

ABSTRACT Escherichia coli fadH encodes a 2,4-dienoyl reductase that plays an auxiliary role in β-oxidation of certain unsaturated fatty acids. In the 2 decades since its discovery, FadH biochemistry has been studied extensively. However, the genetic regulation of FadH has been explored only partially. Here we report mapping of the fadH promoter and document its complex regulation by three independent regulators, the fatty acid degradation FadR repressor, the oxygen-responsive ArcA-ArcB two-component system, and the cyclic AMP receptor protein-cyclic AMP (CRP-cAMP) complex. Electrophoretic mobility shift assays demonstrated that FadR binds to the fadH promoter region and that this binding can be specifically reversed by long-chain acyl-coenzyme A (CoA) thioesters. In vivo data combining transcriptional lacZ fusion and real-time quantitative PCR (qPCR) analyses indicated that fadH is strongly repressed by FadR, in agreement with induction of fadH by long-chain fatty acids. Inactivation of arcA increased fadH transcription by >3-fold under anaerobic conditions. Moreover, fadH expression was increased 8- to 10-fold under anaerobic conditions upon deletion of both the fadR and the arcA gene, indicating that anaerobic expression is additively repressed by FadR and ArcA-ArcB. Unlike fadM, a newly reported member of the E. coli fad regulon that encodes another auxiliary β-oxidation enzyme, fadH was activated by the CRP-cAMP complex in a manner similar to those of the prototypical fad genes. In the absence of the CRP-cAMP complex, repression of fadH expression by both FadR and ArcA-ArcB was very weak, suggesting a possible interplay with other DNA binding proteins.

scholarly journals Phospholipid-dependence of oestrone UDP-glucuronyltransferase and p-nitrophenol UDP-glucuronyltransferase

1979 ◽  
Vol 179 (1) ◽  
pp. 59-65 ◽  
Author(s):  
R H Tukey ◽  
R E Billings ◽  
A P Autor ◽  
T R Tephly
Keyword(s):  
Fatty Acids ◽  
Catalytic Activity ◽  
Column Chromatography ◽  
Unsaturated Fatty Acids ◽  
The Other ◽  
Glucuronyl Transferase ◽  
Hydroxyapatite Column

Hepatic UDP-glucuronyltransferase activity was resolved into two fractions, one exhibiting oestrone glucuronyltransferase activity and the other exhibiting p-nitrophenol glucuronyltransferase activity. Hydroxyapatite-column chromatography removed greater than 95% of the phospholipids from both preparations. The partially purified delipidated enzymes were essentially devoid of catalytic activity, but activities were restored by the addition of phospholipids or phosphatidylcholine mixtures containing various saturated and unsaturated fatty acids. Both oestrone and p-nitrophenol glucuronyl-transferase activities were reconstituted to similar degrees with the phosphatidylcholine mixtures. When purified phospholipids were tested, phosphatidylcholine and lysophosphatidylcholine were most effective in restoring activity, whereas phosphatidylethanolamine was the least effective. These results further suggest that oestrone and p-nitrophenol UDP-glucuronyltransferases are dependent on phospholipids for their activity.

In vitro and in vivo fate of saturated and unsaturated fatty acids during development of insects

1974 ◽  
Vol 360 (3) ◽  
pp. 289-297 ◽  
Author(s):  
A.M. Municio ◽  
J.M. Odriozola ◽  
M.A. Pérez-Albarsanz ◽  
J.A. Ramos
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids

Lipid peroxidation as one mode of action in ochratoxin A toxicity in rats and chicks

1997 ◽  
Vol 77 (2) ◽  
pp. 287-292 ◽  
Author(s):  
Dirk Hoehler ◽  
Ronald R. Marquardt ◽  
Andrew A.F. Rohlich
Keyword(s):  
Lipid Peroxidation ◽  
Fatty Acids ◽  
Ochratoxin A ◽  
Sunflower Oil ◽  
Mode Of Action ◽  
Unsaturated Fatty Acids ◽  
Corn Oil ◽  
Iron Catalyst ◽  
Different Tissues

The objective of this study was to determine whether lipid peroxidation is one mode of action in ochratoxin A (OA) toxicity in vivo. Lipid peroxidation was monitored by analyzing malondialdehyde (MDA) in different tissues by HPLC. A refinement study on the MDA assay was carried out, which showed the importance of the addition of an iron catalyst for the decomposition of hydroperoxides to yield a maximum amount of MDA from a given sample. The rat experiment was designed in a 2 × 2 factorial arrangement using 4 × 6 animals. The four different diets were fed for 21 d and contained either 1% corn oil and 9% tallow (Diets I and III) or 10% corn oil (Diets II and IV); in groups III and IV, 5 mg OA were added per kilogram of diet. For the chick experiment 4 × 8 Leghorn cockerels received diets for 14 d with no added sunflower oil (Diets I and III), whereas the diets of groups II and IV were supplemented with 2.5% sunflower oil. In groups III and IV, 2.5 mg OA were added per kilogram of diet. In both experiments OA decreased the performance of the animals significantly. In the rat experiment an increased lipid peroxidation due to a higher dietary level of unsaturated fatty acids could be obtained, when muscle samples were oxidatively stressed with Fe3+ and ascorbic acid. In the chick experiment there were very clear effects of the dietary treatment on the MDA concentrations of different tissues, as both a higher supply with unsaturated fatty acids and OA increased most of the MDA values significantly. These data suggest that lipid peroxides are formed in vivo by OA, but the effects may vary considerably from species to species, and may also be influenced by other factors. Key words: Ochratoxin A, lipid peroxidation, malondialdehyde, rat, chick

Effect of toluene on erythrocyte membrane stability under in vivo and in vitro conditions with assessment of oxidant/antioxidant status

2009 ◽  
Vol 25 (8) ◽  
pp. 545-550 ◽  
Author(s):  
Ismail Karabulut ◽  
Z. Dicle Balkanci ◽  
Bilge Pehlivanoglu ◽  
Aysen Erdem ◽  
Ersin Fadillioglu
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Unsaturated Fatty Acids ◽  
Osmotic Fragility ◽  
Human Erythrocytes ◽  
Antioxidant Enzyme Activities ◽  
Oxidative Stress Parameters ◽  
Stress Parameters

Toluene, an organic solvent used widely in the industry, is highly lipophilic and accumulates in the cell membrane impeding transport through it. Its metabolites cause oxygen radical formation that react with unsaturated fatty acids and proteins in erythrocytes leading to lipid peroxidation and protein breakdown. In this study, we aimed to investigate the membrane stabilizing and the oxidative stress—inducing effects of toluene in human erythrocytes. Measurements of osmotic fragility, mean corpuscular volume (MCV), oxidative stress parameters and antioxidant enzyme activities were performed simultaneously both in individuals exposed to toluene professionally (in vivo) and human erythrocytes treated with toluene (in vitro). To measure osmotic fragility, erythrocytes were placed in NaCl solutions at various concentrations (0.1% [blank], 0.38%, 0.40%, 0.42%, 0.44%, 0.46%, 0.48% and 1% [stock]). Percentage of haemolysis in each solution was calculated with respect to the 100% haemolysis in the blank solution. The erythrocyte packs prepared at the day of the above-mentioned measurements were kept at —80°C until the time for determination of malonyldialdehyde and protein carbonyl levels, and catalase (CAT) and glutathione peroxidase activities as indicators of oxidative stress. Toluene increased oxidative stress parameters significantly both in vivo and in vitro; it also caused a significant decrease in the activities of antioxidant enzymes. Osmotic fragility was altered only in the case of in vitro exposure. In conclusion, toluene exposure resulted in increased lipid peroxidation and protein damage both in vivo and in vitro. Although, it is natural to expect increased osmotic fragility due to oxidative properties of toluene, its membrane-stabilizing effect overcame the oxidative properties leading to decreased osmotic fragility or preventing its deterioration in vitro and in vivo toluene exposures, respectively, in the present study.

Sign in / Sign up

Export Citation Format

Share Document