The inhibitory effect of graphene oxide on photocatalytic hydrogenation from organic fatty acids

2018 ◽  
Vol 38 (2) ◽  
pp. 410-416 ◽  
Author(s):  
Wen Zhang ◽  
Yang Li ◽  
Changqing Liu ◽  
Taha Marhaba
Keyword(s):  
Fatty Acids ◽  
Graphene Oxide ◽  
Inhibitory Effect

scholarly journals Evidence for the regulation of guinea-pig heart microsomal phosphatidylcholine-hydrolysing phospholipase A1 by guanosine 5′-[γ-thio]triphosphate

1992 ◽  
Vol 288 (3) ◽  
pp. 965-968 ◽  
Author(s):  
K Badiani ◽  
X Lu ◽  
G Arthur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Guinea Pig ◽  
Molecular Species ◽  
Inhibitory Effect ◽  
Phospholipase A1 ◽  
Guinea Pig Heart ◽  
Substrate Specificities ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have recently characterized lysophospholipase A2 activities in guinea-pig heart microsomes and postulated that these enzymes act sequentially with phospholipases A1 to release fatty acids selectively from phosphatidylcholine (PC) and phosphatidylethanolamine, thus providing an alternative route to the phospholipase A2 mode of release. In a further investigation of the postulated pathway, we have characterized the PC-hydrolysing phospholipase A1 in guinea-pig heart microsomes. Our results show that the enzyme may have a preference for substrates with C16:0 over C18:0 at the sn-1 position. In addition, although the enzyme cleaves the sn-1 fatty acid, the rate of hydrolysis of PC substrates with C16:0 at the sn-1 position was influenced by the nature of the fatty acid at the sn-2 position. The order of decreasing preference was C18:2 > C20:4 = C18:1 > C16:0. The hydrolyses of the molecular species were differentially affected by heating at 60 degrees C. An investigation into the effect of nucleotides on the activity of the enzyme showed that guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited the hydrolysis of PC by phospholipase A1 activity, whereas GTP, guanosine 5′-[beta-thio]diphosphate (GDP[S]), GDP, ATP and adenosine 5′-[gamma-thio]triphosphate (ATP[S]) did not affect the activity. The inhibitory effect of GTP[S] on phospholipase A1 activity was blocked by preincubation with GDP[S]. A differential effect of GTP[S] on the hydrolysis of different molecular species was also observed. Taken together, the results of this study suggest the presence of more than one phospholipase A1 in the microsomes with different substrate specificities, which act sequentially with lysophospholipase A2 to release linoleic or arachidonic acid selectively from PC under resting conditions. Upon stimulation and activation of the G-protein, the release of fatty acids would be inhibited.

Impact of UV-B Radiation on the Lipid and Fatty Acid Composition of Synchronized Ditylum brightwellii (West) Grunow

1994 ◽  
Vol 49 (9-10) ◽  
pp. 607-614 ◽  
Author(s):  
Günter Döhler ◽  
Thomas Biermann
Keyword(s):  
Cell Cycle ◽  
Fatty Acids ◽  
Dark Period ◽  
Inhibitory Effect ◽  
Light Period ◽  
Marine Diatom ◽  
Lag Phase ◽  
Ditylum Brightwellii ◽  
Acyl Lipids ◽  
The Impact

Abstract The marine diatom Ditylum brightwellii (West) Grunow isolated from the Baltic Sea could be synchronized by a light/dark rhythm of 6.5:17.5 h (white light intensity 8 W m-2) at 18 °C and 0.035 vol.% CO2. Content of protein, DNA and RNA increased linearly up to the end of the cell cycle. Pigments (chlorophyll a, chlorophyll c1 + c2, carotenoids) and galactolipids were synthesized in the light period only. A lag phase of 2 h was observed in the biosynthesis of sulphoquinovosyl diacylglycerol and phosphatidylglycerol. Formation of phosphatidylglycerol and phosphatidylcholin continued in the dark period (30% and 28%, respectively). The pattern of major fatty acids (C14:0, C16:1, C16:0, C18:1 and C20:5) varied during the cell cycle of Ditylum.Biosynthesis of acyl lipids was reduced in dependence on the UV-B dose. The most sensitive lipid was digalactosyl diacylglycerol (total inhibition at 585 J m-2), whereas phosphatidylcholin was less affected (20% reduction). UV-B radiation during the dark period had no effect on the lipid and pigment content. Strongest inhibitory effect of UV-B on cell division, synthesis of protein, pigments, sulphoquinovosyl diacylglycerol and phosphatidylglycerol was found after UV-B radiation at the beginning of the cell cycle (0.-2. h). An exposure time at the end of the light period (4.-6. h) led to a marked damage on the synthesis of monogalactosyl diacylglycerol and phosphatidylglycerol. These findings indicate a stage-dependent response of Ditylum to UV-B irradiance. The impact of UV-B resulted in an increase of unsaturated long chained fatty acids (C18, C20) and in a diminution of short chained fatty acids (C14, C16). Content of ATP was not affected by UV-B radiation under the used conditions. The inhibitory effect of UV-B on synthesis of DNA, RNA, protein and acyl lipids was mainly reversible. Results were discussed with reference to UV-B damage on the enzymes involved in the biosynthesis of acyl lipids and by a reduction of available metabolites.

Inhibition of DNA replication by fish oil-treated cytoplasm is counteracted by fish oil-treated nuclear extract

2002 ◽  
Vol 283 (5) ◽  
pp. C1365-C1375 ◽  
Author(s):  
Sybille Rex ◽  
Maria A. Kukuruzinska ◽  
Nawfal W. Istfan
Keyword(s):  
Fatty Acids ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Fish Oil ◽  
Corn Oil ◽  
Nuclear Extract ◽  
Inhibitory Effect ◽  
Free System ◽  
Nuclear Factors ◽  
Cytosolic Extract

We have recently noted that cells treated with fish oil and n–3-fatty acids show slower DNA replication rates than cells treated with a control emulsion or corn oil only. However, it is not clearly understood how such an effect is induced. Fish oil and its metabolites are known to have several modulating effects on signal transduction pathways. Alternatively, they may influence DNA replication by interacting directly with nuclear components. To investigate this problem in greater detail, we have studied the kinetics of DNA synthesis in a cell-free system derived from HeLa cells. Nuclei and cytosolic extract were isolated from cells synchronized in early S phase after treatment with control emulsion, corn oil, or fish oil, respectively. The nuclei were reconstituted with cytosolic extract and a reaction mixture containing bromodeoxyuridine (BrdU) triphosphate to label newly synthesized DNA. The rate of DNA synthesis was measured by bivariate DNA/BrdU analysis and flow cytometry. We show that fish oil-treated cytosol inhibits the elongation of newly synthesized DNA by ∼80% in control nuclei. However, nuclei treated with fish oil escape this inhibitory effect. We also show that addition of nuclear extract from fish oil-treated cells reverses the inhibitory effect seen in the reconstitution system of control nuclei and fish oil-treated cytosol. These results indicate that polyunsaturated fatty acids can modulate DNA synthesis through cytosolic as well as soluble nuclear factors.

Control of plasma levels of growth hormone, glucagon and insulin in ducklings: roles of free fatty acids and somatostatin

1985 ◽  
Vol 106 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Ch. Foltzer ◽  
M. Th. Strosser ◽  
S. Harvey ◽  
P. Mialhe
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Free Fatty Acids ◽  
Glucagon Secretion ◽  
Inhibitory Effect ◽  
Immunoreactive Insulin ◽  
Plasma Ffa ◽  
Plasma Gh ◽  
Glucagon And Insulin ◽  
Somatostatin 14

ABSTRACT The effects of plasma free fatty acids (FFA) and somatostatin-14 (S-14) on concentrations of plasma GH, glucagon and insulin were investigated in juvenile ducks. Oleic acid, S-14 or both were infused into 4- to 7-week-old birds and plasma GH, glucagon-like immunoreactivity (GLI), immunoreactive insulin (IRI) and FFA were measured. An increase in plasma GH and a decrease in GLI but no change in IRI was observed after infusion of 9 mg oleic acid/kg per min. A decrease in plasma GH, FFA and IRI and an increase in plasma GLI was seen after infusion of 800 ng S–14/kg per min. These effects of S-14 on IRI and GLI were abolished when S-14 was infused simultaneously with oleic acid. It is concluded that FFA have a direct stimulatory effect on GH secretion and an inhibitory effect on glucagon secretion. Somatostatin-14 directly inhibits the secretion of GH and its stimulatory effect on the secretion of glucagon is mediated by a depression in concentrations of plasma FFA. Finally, S-14 has no effect on plasma insulin when basal levels of plasma FFA are maintained. J. Endocr. (1985) 106, 21–25

Inhibition of Bacterial Spore Growth by Fatty Acids and Their Sodium Salts

1992 ◽  
Vol 55 (12) ◽  
pp. 980-984 ◽  
Author(s):  
LAHSEN ABABOUCH ◽  
AHMED CHAIBI ◽  
FRANCIS F. BUSTA
Keyword(s):  
Fatty Acids ◽  
Antimicrobial Activity ◽  
Linolenic Acid ◽  
Lauric Acid ◽  
Clostridium Botulinum ◽  
Saturated Fatty Acids ◽  
Inhibitory Effect ◽  
Clostridium Sporogenes ◽  
Sodium Salts ◽  
Inhibit Spore Germination

The antimicrobial activity of 11 fatty acids and their salts was tested on spores of Clostridium botulinum 62A, Clostridium sporogenes PA3679, and Bacillus cereus F4165/75. Linolenic acid was the most inhibitory fatty acid and lauric acid was the most inhibitory of the saturated fatty acids. Minimum inhibitory concentrations ranged from 50–150 μg/ml for lauric acid, ≥150 μg/ml for myristic acid, 30–100 μg/ml for linoleic acid, and 10–75 μg/ml for linolenic acid depending on the strain. Caprylic, capric, palmitic, stearic, arachidic, and erucic acids showed only partial inhibition (44 to 90%) at concentrations as high as 150 μg/ml. Addition of 0.2–0.3% (wt/vol) starch neutralized the inhibitory effect of palmitic, linoleic, and linolenic acids but had no effect on lauric acid even when increased to 1%. Lauric, linoleic, and linolenic acids were shown to inhibit spore germination as measured by loss of spore heat resistance.

Unsaturated fatty acids and cyclooxygenase inhibitors: effects on pial arterioles

1982 ◽  
Vol 242 (4) ◽  
pp. H629-H632
Author(s):  
W. I. Rosenblum
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Eicosatrienoic Acid ◽  
Inhibitory Effect ◽  
Cyclooxygenase Inhibitors ◽  
Dependent Manner ◽  
Double Bonds ◽  
Pial Arterioles ◽  
Dose Dependent

Cerebral surface arterioles of the mouse were constricted in a dose-dependent manner by three different unsaturated fatty acids each with one of its double bonds in the n-6 position: arachidonate, linoleic, and 11,14,17-eicosatrienoic acid (ETA) in doses of 10-200 micrograms/ml. The constriction was transient, and its magnitude was significantly reduced by pretreatment of the mice with intraperitoneal injections of indomethacin (5 mg/kg), aspirin (100 mg/kg), or sodium 2-amino-3-(4 chlorobenzyl)-phenylacetate (AHR-6293, 100 mg/kg). The inhibitory effect of these cyclooxygenase inhibitors suggests that this enzyme is involved in the response to these fatty acids and is in keeping with suggestions in the literature stating that such unsaturated fatty acids may interact with cyclooxygenase even when they cannot form prostaglandin (PG) endoperoxides, The PG endoperoxide formed by arachidonate or the analogous hydroperoxy compounds formed by linoleic or 11,14,17 ETA, may then alter cerebrovascular tone by production of reactive, O2-containing species. Alternate explanations for the data are also proposed.

Effects of fatty acids on exercise plus insulin-induced glucose utilization in trained and sedentary subjects

2002 ◽  
Vol 282 (1) ◽  
pp. E125-E131 ◽  
Author(s):  
Oscar Matzinger ◽  
Philippe Schneiter ◽  
Luc Tappy
Keyword(s):  
Fatty Acids ◽  
Lipid Oxidation ◽  
Endurance Training ◽  
Glucose Utilization ◽  
Inhibitory Effect ◽  
Substrate Oxidation ◽  
Whole Body ◽  
Trained Subjects ◽  
Lipid Infusion ◽  
Sedentary Subjects

Fatty acids are known to decrease insulin-mediated glucose utilization in humans, both at rest and during exercise. To evaluate the effect of endurance training in this process, we infused lipids or saline in groups of sedentary and highly trained subjects. Whole body glucose utilization and substrate oxidation were monitored during a 2.5-h hyperinsulinemic clamp. During the last 30 min, a cycling exercise was superimposed. During hyperinsulinemia at rest, whole body glucose utilization and glucose oxidation were higher in trained subjects than in sedentary subjects. Compared with the control experiments with the antilipolytic agent acipimox, lipid infusion stimulated lipid oxidation to the same extent in trained as in sedentary subjects. It reduced whole body glucose utilization by 37% in trained and by 41% in sedentary subjects. During exercise, lipid infusion increased more lipid oxidation in trained than in sedentary subjects and reduced whole body glucose utilization by 43 ± 4% in trained and by 22 ± 4% in sedentary subjects ( P < 0.01). The present data indicate that lipid infusion has similar effects on lipid oxidation and whole body glucose utilization during hyperinsulinemia at rest in trained and sedentary subjects. During exercise, however, it increases more lipid oxidation and produces a more important reduction in glucose utilization in trained than in sedentary subjects. These results suggest that endurance training enhances the inhibitory effect of lipids on whole body glucose metabolism during exercise.

Sign in / Sign up

Export Citation Format

Share Document