linoleic-acid and thiobarbituric-acid

The antioxidant activity of the aminodi(hetero)arylamines, prepared by C-N coupling of the methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with bromonitrobenzenes and further reduction of the obtained nitro compounds, was evaluated by chemical, biochemical and electrochemical assays. The aminodi(hetero)arylamine with the amino group ortho to the NH and a methoxy group in para, was the most efficient in radical scavenging activity (RSA, 63 µM) and reducing power (RP, 33 µM), while the aminodiarylamine with the amino group in para to the NH, gave the best results in β-carotene-linoleate system (41 µM) and inhibition of formation of thiobarbituric acid reactive substances in porcine brain cells homogenates (7 µM), with EC50 values even lower than those obtained for the standard trolox. This diarylamine also presented the lowest oxidation potential, lower than the one of trolox, and the highest antioxidant power in the electrochemical assays. The para substitution with an amino group enables higher antioxidant potential.

Topics: Amines; Animals; beta Carotene; Brain; Chromans; Electrochemical Techniques; Free Radical Scavengers; Linoleic Acid; Lipid Peroxidation; Nitrobenzenes; Pyridines; Structure-Activity Relationship; Swine; Thiobarbiturates; Tissue Extracts

The reaction between 2-thiobarbituric acid (H(2)TBA), which was treated with an equimolar amount of potassium hydroxide, in a water with triphenytin chloride in methanol, results in the formation of the {[Ph(3)Sn(O-HTBA)]}(n) (1) complex. Crystals of the hydrated 1 with formula {[Ph(3)Sn(O-HTBA)]·0.7(H(2)O)}(n) were growth from methanol/acetonitrile solution, of the white precipitation, filtered off, from the reaction. The crystal structure of complex 1 has been determined by X-ray diffraction at 120 K. Complex 1 is polymeric. The geometry around the tin(IV) ions is trigonal bi-pyramidal with coordination to three C atoms from phenyl groups and one O atom from a de-protonated HTBA ligand. Complex 1 and the already known [(n-Bu)(3)Sn(O-HTBA)·H(2)O] (2) were evaluated for their in vitro cytotoxic activity (cell viability) against human cancer cell lines: HeLa (cervical), OAW-42 (ovarian), MCF-7 (breast, ER positive), MDA-MB-231 (breast, ER negative), A549 (lung), Caki-1 (renal) and additionally, the normal human lung cell line MRC-5 (normal human fetal lung fibroblast cells) and normal immortalized human mammary gland epithelial cell line MTSV17 with a Trypan Blue assay. Moreover complex 1 was evaluated for its in vitro cell growth proliferation activity against leiomyosarcoma cells (LMS), MCF-7 and MRC-5 cells with a Thiazolyl Blue Tetrazolium Bromide (MTT) assay. The type of cell death caused by complexes 1 and 2 was also evaluated by use of flow cytometry assay. The results showed that these compounds mediate a strong cytotoxic response to normal and cancer cell lines tested through apoptosis and induce cell cycle arrest in S phase of the cell cycle, suggesting DNA intercalation (direct or indirect) with the complexes. Finally, the influence of these complexes 1 and 2 upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX) was kinetically and theoretically studied.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Coordination Complexes; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Fibroblasts; HeLa Cells; Humans; Hydroxides; Intercalating Agents; Linoleic Acid; Lipoxygenase; MCF-7 Cells; Organotin Compounds; Potassium Compounds; S Phase Cell Cycle Checkpoints; Structure-Activity Relationship; Thiobarbiturates

Reactive oxygen species formed as a response to various abiotic and biotic stresses cause an oxidative damage of cellular component such are lipids, proteins and nucleic acids. Lipid peroxidation is considered as one of the major processes responsible for the oxidative damage of the polyunsaturated fatty acid in the cell membranes. Various methods such as a loss of polyunsaturated fatty acids, amount of the primary and the secondary products are used to monitor the level of lipid peroxidation. To investigate the use of ultra-weak photon emission as a non-invasive tool for monitoring of lipid peroxidation, the involvement of lipid peroxidation in ultra-weak photon emission was studied in the unicellular green alga Chlamydomonas reinhardtii. Lipid peroxidation initiated by addition of exogenous linoleic acid to the cells was monitored by ultra-weak photon emission measured with the employment of highly sensitive charged couple device camera and photomultiplier tube. It was found that the addition of linoleic acid to the cells significantly increased the ultra-weak photon emission that correlates with the accumulation of lipid peroxidation product as measured using thiobarbituric acid assay. Scavenging of hydroxyl radical by mannitol, inhibition of intrinsic lipoxygenase by catechol and removal of molecular oxygen considerably suppressed ultra-weak photon emission measured after the addition of linoleic acid. The photon emission dominated at the red region of the spectrum with emission maximum at 680 nm. These observations reveal that the oxidation of linoleic acid by hydroxyl radical and intrinsic lipoxygenase results in the ultra-weak photon emission. Electronically excited species such as excited triplet carbonyls are the likely candidates for the primary excited species formed during the lipid peroxidation, whereas chlorophylls are the final emitters of photons. We propose here that the ultra-weak photon emission can be used as a non-invasive tool for the detection of lipid peroxidation in the cell membranes.

Topics: Cell Membrane; Chlamydomonas reinhardtii; Histidine; Hydroxyl Radical; Linoleic Acid; Lipid Peroxidation; Lipoxygenase; Lipoxygenase Inhibitors; Malondialdehyde; Mannitol; Oxygen; Photons; Thiobarbiturates

To clarify the alternative mechanisms to vitamin E (VE) regulating lipid peroxide accumulation in the liver after docosahexaenoic acid (DHA) ingestion, we examined the relationship between the DHA-induced lipid peroxide formation and induction of the xenobiotic transporters, Ral-binding GTPase-activating protein (RalBP1) and multidrug resistance-associated proteins 1, 2 and 3 (MRP1-3), in the liver of rats fed with DHA. The test diets contained DHA and linoleic acid (LA) (8.7% and 2.1% of total energy, respectively) with different levels of dietary VE (normal and low: 68 and 7.7 mg of alpha-tocopherol equivalent per kg diet, respectively), and the control diet contained LA alone (11.5% of total energy). The rats were fed with these experimental diets for 14 d. The proportions of DHA in the liver, kidney and heart were higher in the DHA-fed groups than in the LA-fed group. The tissue thiobarbituric acid values as an index of lipid peroxidation were also significantly higher in the DHA-fed groups, but the value did not differ between the DHA-fed groups with different VE levels. In the liver, there were no significant differences in the glutathione S-transferase (GST) and aldehyde dehydrogenase (ALDH) activities or in the expression of GST M2, RalBP1, MRP1 and MRP2 mRNA. However, the obvious induction of expression of liver MRP3 mRNA and tendency to produce the protein were recognized after DHA ingestion. This study is the first to report the gene expression of MRP3 by DHA ingestion. There might exist, therefore, some relationship between the DHA intake and MRP3 induction in regulating lipid peroxide accumulation in the liver.

Topics: Aldehyde Dehydrogenase; Animals; Antioxidants; Diet; Docosahexaenoic Acids; Glutathione Transferase; GTPase-Activating Proteins; Linoleic Acid; Lipid Peroxidation; Lipid Peroxides; Liver; Male; Membrane Transport Proteins; Multidrug Resistance-Associated Protein 2; Multidrug Resistance-Associated Proteins; Rats; Rats, Sprague-Dawley; Thiobarbiturates; Vitamin E

The thiobarbituric acid reactive substances (TBARS) assay is a commonly used method for the detection of lipid peroxidation. Malondialdehyde is formed as a result of lipid peroxidation and reacts with thiobarbituric acid to form a pink pigment that has an absorption maximum at 532 nm. Other compounds also react with thiobarbituric acid to form colored species that can interfere with this assay, but little is known about these interfering species. This is the first investigation using LC-MS and MS-MS to study the structures of the pink adduct as well as a common unstable yellow interference compound, which absorbs at 455 nm. Also, the presence of barbituric acid impurities in the thiobarbituric acid reagent was found to produce 1:1:1 thiobarbituric acid/malondialdehyde/barbituric acid and 2:1 barbituric acid/malondialdehyde adducts that absorbed at 513 and 490 nm, respectively, indicating that thiobarbituric acid should be purified before use.

Topics: Barbiturates; Chromatography, Liquid; Linoleic Acid; Lipid Peroxidation; Malondialdehyde; Mass Spectrometry; Thiobarbiturates; Thiobarbituric Acid Reactive Substances

The degree of plasma membrane fatty acid unsaturation and the copper sensitivity of Saccharomyces cerevisiae are closely correlated. Our objective was to determine whether these effects could be accounted for by differential metal induction of lipid peroxidation. S. cerevisiae S150-2B was enriched with the polyunsaturated fatty acids (PUFAs) linoleate (18:2) and linolenate (18:3) by growth in 18:2- or 18:3-supplemented medium. Potassium efflux and colony count data indicated that sensitivity to both copper (redox active) and cadmium (redox inactive) was increased in 18:2-supplemented cells and particularly in 18:3-supplemented cells. Copper- and cadmium-induced lipid peroxidation was rapid and associated with a decline in plasma membrane lipid order, detected by fluorescence depolarization measurements with the membrane probe trimethylammonium diphenylhexatriene. Levels of thiobarbituric acid-reactive substances (lipid peroxidation products) were up to twofold higher in 18:2-supplemented cells than in unsupplemented cells following metal addition, although this difference was reduced with prolonged incubation up to 3 h. Conjugated-diene levels in metal-exposed cells also increased with both the concentration of copper or cadmium and the degree of cellular fatty acid unsaturation; maximal levels were evident in 18:3-supplemented cells. The results demonstrate heavy metal-induced lipid peroxidation in a microorganism for the first time and indicate that the metal sensitivity of PUFA-enriched S. cerevisiae may be attributable to elevated levels of lipid peroxidation in these cells.

Topics: alpha-Linolenic Acid; Cadmium; Cell Membrane; Colony Count, Microbial; Copper; Culture Media; Diphenylhexatriene; Fatty Acids; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Lipids; Potassium; Saccharomyces cerevisiae; Thiobarbiturates

In order to develop a new type of antioxidative compound which has both the phenolic and beta-diketone moiety in the same molecule, we converted three known curcuminoids, curcumin (diferuloylmethane, U1), (4-hydroxy-3-methoxycinnamoyl)methane (U2), and bis-(4-hydroxycinnamoyl)methane (U3), which are the natural antioxidants of Curcuma longa L. (tumeric), to tetrahydrocurcuminoids (THU1, THU2, and THU3, respectively) by hydrogenation, and evaluated their antioxidative activity by using linoleic acid as the substrate in an ethanol/water system. Further, we used the rabbit erythrocyte membrane ghost and rat liver microsome as in vitro systems and determined the antioxidative activity of these curcuminoids. When we evaluated their antioxidative activity by these assays, it was found that THU1 had the strongest antioxidative activity among all curcuminoids in each assay system. THU1 has been reported to be one of the main metabolites of U1 in vivo [Holder et al., Xenobiotica, 8, 761-768 (1978)]. These results suggest that THU1 must play an important role in the antioxidative mechanism of U1 in vivo by converting U1 into THU1.

Topics: Animals; Antioxidants; Curcumin; Erythrocyte Membrane; Hydrogenation; Linoleic Acid; Linoleic Acids; Methane; Microsomes, Liver; Oxidation-Reduction; Rabbits; Rats; Rats, Wistar; Structure-Activity Relationship; Thiobarbiturates; Thiocyanates

The effects of dietary pantethine levels on the contents and compositions of fatty acids and on the levels of lipid peroxides were investigated with rat liver and its S-9 fraction under administration of 0 (non), 0.2 (low dose), and 0.35 ml (high dose) of autoxidized linoleate (AL) per 100 g body weight of the rats per day for 5 days. AL having 800 meq/kg of peroxide value (PV) and 1,700 meq/kg of carbonyl value (CV) was dosed to the rats of each group given drinking water containing 0 mg% (deficient), 6.25 mg% (adequate), and 125 mg% pantethine (excess). In the pantethine-deficient and -adequate groups, the contents of fatty acids both in the liver homogenate and in the S-9 fraction were correspondingly decreased by increasing dose levels of AL, and the decrease was remarkable especially in the pantethine-deficient group, but was not significant in the pantethine-excess group even by a high dose of AL. Particularly, in the high dose of AL, the notable decreases of oleic acid (C18:1) contents in both the liver and the S-9 fraction were observed in rats of the pantethine-deficient and -adequate groups. The thiobarbituric acid (TBA) values in the liver homogenate and the S-9 fraction were increased correspondingly by increasing dose levels of AL, and the increases were repressed in the pantethine-excess group.

Topics: Administration, Oral; Animals; Body Weight; Chromatography, Gas; Fatty Acids; In Vitro Techniques; Linoleic Acid; Linoleic Acids; Liver; Male; Malondialdehyde; Pantetheine; Rats; Rats, Inbred Strains; Thiobarbiturates

Alloxan-diabetic rats and age-matched controls were killed after 6 weeks of diabetes; heart and kidneys were removed and assayed for thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides, lipid phosphorus, total fatty acid composition and glutathione. Tissue homogenates from a second group of diabetic and control rats were incubated in oxygen-saturated buffer with and without the free radical generating system Fe2+/ascorbate (0.1/1.0 mM) and were assayed for lipid peroxidation. Diabetic hearts contained markedly lower levels of TBARS and lipid hydroperoxides (40% and 18%, respectively) than control hearts, whereas differences in TBARS were less pronounced in kidneys (9%). Incubation of homogenates of both organs in the presence or absence of Fe2+/ascorbate for up to 2 h yielded significantly lower levels of TBARS and lipid hydroperoxides with diabetic tissue. Diabetic hearts and kidneys contained higher levels of glutathione (28% and 13% over controls) and both diabetic tissues showed much higher linoleate/arachidonate ratios than did the controls (9.86 vs. 2.56 for heart, 2.01 vs. 0.86 for kidney). We conclude that diabetic tissues develop enhanced defense systems against oxidative stress and we assume tha the lower levels of arachidonate contribute to their resistance to lipid peroxidation as well.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Ascorbic Acid; Diabetes Mellitus, Experimental; Fatty Acids; Ferrous Compounds; Free Radicals; Glutathione; Kidney; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Lipid Peroxides; Male; Myocardium; Phosphorus; Rats; Rats, Inbred Strains; Thiobarbiturates

Peroxidation of linoleic acid was found to be induced by interaction with haemoglobin and hydrogen peroxide. The peroxidation of linoleic acid induced by this interaction was inhibited by desferrioxamine, ethylenediaminetetraacetic acid or alpha-tocopherol, and poorly by catalase. However, it was accelerated by ascorbic acid.

Topics: Hemoglobins; Hydrogen Peroxide; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Thiobarbiturates