ascorbic-acid and stearic-acid

Evidence continues to accumulate that implicates the oxidative modification of low-density lipoprotein (LDL) in the pathogenesis of atherosclerosis. Numerous studies have indicated the existence of oxidized LDL in vivo. Supplementation of animals and humans with antioxidants such as alpha-tocopherol have shown promise in reducing the extent of LDL oxidation. However, another possible means of preventing LDL oxidative modification may be by reducing the amount of oxidizable polyunsaturated fatty acids in the LDL particle. Monounsaturated fatty acids have been shown to decrease the susceptibility of LDL oxidation in human studies. It remains to be seen whether saturated fatty acids can do the same. Stearic acid, found in cocoa butter, would be an ideal saturated fatty acid to test because it has a neutral effect on the plasma lipid profile.

Topics: Animals; Antioxidants; Ascorbic Acid; beta Carotene; Carotenoids; Fatty Acids; Humans; Lipoproteins, LDL; Oxidation-Reduction; Stearic Acids; Vitamin E; Vitamins

The present study investigated the effect of the consumption of two cheese varieties differing for fat quality on blood lipid profile and redox status biomarkers in 30 selected healthy volunteers, consuming either the experimental cheese (from milk produced by cows fed a grass and maize silage based diet with 5% of linseed oil added) or the control cheese (from normal cows' milk) for 4 weeks according to a crossover design. The experimental cheese had a lower content of medium-chain saturated fatty acids and a higher content of stearic acid and polyunsaturated fatty acids; its consumption led to higher levels of vitamins C and E and stearic acid in blood, while myristic acid and oxidized low-density lipoprotein concentrations were significantly lower. As myristic acid and oxidized low-density lipoprotein are highly correlated with increased atherogenic risk and vitamins C and E with antioxidant activity, the enrichment of cows' diet with linseed oil could provide a dietary option to prevent cardiovascular diseases risk.

Topics: Adult; Animals; Antioxidants; Ascorbic Acid; Biomarkers; Cattle; Cheese; Cross-Over Studies; Diet; Dietary Fats; Double-Blind Method; Fatty Acids; Female; Flax; Food, Fortified; Humans; Linseed Oil; Lipids; Lipoproteins, LDL; Male; Myristic Acid; Oxidation-Reduction; Pilot Projects; Reference Values; Silage; Stearic Acids; Vitamin E; Young Adult

Vitamin C (Vit C) is an important physiological antioxidant with growing applications in cancer. Somatostatin (SST) is a natural peptide with growth inhibitory effect in several mammary cancer models.. The combined effects of SST and Vit C supplementation have never been studied in breast cancer cells so far.. We used MCF-7 and MDA-MB231 breast cancer cells incubated with SST for 24h, in the absence and presence of Vit C, at their EC50 concentrations, to evaluate membrane fatty acid-profiles together with the follow-up of EGFR and MAPK signaling pathways.. The two cell lines gave different membrane reorganization: in MCF-7 cells, decrease of omega-6 linoleic acid and increase of omega-3 fatty acids (Fas) occurred after SST and SST+Vit C incubations, the latter also showing significant increases in MUFA, docosapentaenoic acid and mono-trans arachidonic acid levels. In MDA-MB231 cells, SST+Vit C incubation induced significant membrane remodeling with an increase of stearic acid and mono-trans-linoleic acid isomer, diminution of omega-6 linoleic, arachidonic acid and omega-3 (docosapentaenoic and docosadienoic acids). Distinct signaling pathways in these cell lines were studied: in MCF-7 cells, incubations with SST and Vit C, alone or in combination significantly decreased EGFR and MAPK signaling, whereas in MDA-MB231 cells, SST and Vit C incubations, alone or combined, decreased p- P44/42 MAPK levels, and increased EGFR levels.. Our results showed that SST and Vit C can be combined to induce membrane fatty acid changes, including lipid isomerization through a specific free radical-driven process, influencing signaling pathways.

Topics: Arachidonic Acids; Ascorbic Acid; Breast Neoplasms; Cell Extracts; Cell Line, Tumor; Cell Membrane; Fatty Acids; Fatty Acids, Omega-3; Fatty Acids, Unsaturated; Green Fluorescent Proteins; Humans; Lipids; Mitogen-Activated Protein Kinase Kinases; Phospholipids; Signal Transduction; Somatostatin; Stearic Acids

Oleogels were produced using a phytosterol blend of β-sitosterol/γ-oryzanol or a blend of sucrose stearate/ascorbyl palmitate (SSAP) as oleogelators. Four lipid phases were compared in oleogel formation for each oleogelator blend: menhaden oil, structured lipid (SL) of menhaden oil and 30 mol% caprylic acid (SL-C), SL of menhaden oil and 20 mol% stearic acid (SL-S), and SL of menhaden oil and 14 mol% each of caprylic and stearic acid (SL-CS). All SLs were produced enzymatically using a recombinant lipase from Candida antarctica as the biocatalyst. Menhaden oil, SL, phytosterol, or SSAP oleogels were evaluated as alternatives to shortening in the preparation of yellow cake in terms of batter and cake physicochemical properties. The shortening, phytosterol, and SSAP oleogel batters exhibited statistically similar specific gravities (0.85). The shortening, and menhaden oil phytosterol and SSAP oleogel batters, exhibited similar Power-Law values (n: 0.78, k: 31 Pa s

Topics: Ascorbic Acid; Caprylates; Fat Substitutes; Fatty Acids; Fish Oils; Food Analysis; Food Handling; Gels; Organic Chemicals; Phenylpropionates; Phytosterols; Sitosterols; Stearic Acids; Sucrose

This paper introduces a rapid automated process-development approach for a continuous capsule-filling process. In our proposed method, both the material attributes and the critical process parameters were varied to understand and to optimize the overall process. Using our approach a statistical process model can be generated with unprecedented speed (2 days), which is the prerequisite for effectively developing and operating continuous process platforms. In a first set of experiments a process model was developed using different mixture compositions of ascorbic acid, lactose and magnesium stearate while changing simultaneously the critical process parameters of the capsule filler (speed, pressure, immersion depth and powder bed height). Targets of the model were the mean fill weight and the relative standard deviation of the produced capsules. In a second experimental set the model was tested, i.e., the goal was to predict the behavior of the system at different set points in order to predict weight and relative standard deviation for predefined targets. Predictions were very good, thus validating our approach. The combination of the rapid automated process development approach and the continuous capsule-filling process resulted in a new strategy for the development and manufacture of pharmaceutical dosage forms.

Topics: Ascorbic Acid; Capsules; Drug Compounding; Lactose; Stearic Acids

The synthesis of D-isoascorbyl stearate from D-isoascorbic acid and stearic acid with immobilized lipase (Novozym(®)435) as catalyst was studied. Response surface methodology and Box-Behnken design with six variables and three levels were employed to evaluate the effects of processing conditions on the conversion of D-isoascorbic acid. The results confirmed that the response surface method and statistical analysis were proved to be useful in developing optimal conditions for D-isoascorbyl stearate synthesis. The optimum conditions were predicted as follows: reaction temperature 48 °C, reaction time 17.7 h, immobilized lipase amount 50.0 % (w/w, of D-isoascorbic acid), substrate molar ratio 9:1 (stearic acid to D-isoascorbic acid), D-isoascorbic acid concentration 0.14 mol/L (based on solvent), 4A molecular sieve addition 200 g/L (based on solvent), and the optimal conversion was 90.6 %. Through the kinetics model fitting of the esterification, it was considered that the esterification conformed to a Ping-Pong bi-bi kinetic model with D-isoascorbic acid inhibition, and the obtained kinetic constants showed that the inhibition of D-isoascorbic acid and the enzyme affinity to substrate were abate with the increase of the reaction temperature.

Topics: Ascorbic Acid; Biocatalysis; Candida; Enzymes, Immobilized; Esterification; Fungal Proteins; Industrial Microbiology; Kinetics; Lipase; Solvents; Stearic Acids; Surface Properties; Temperature

The paper deals with a study of tensile strength and disintegration time of compacts made from silicified microcrystalline celluloses, Prosolv SMCC 90, and Prosolv HD 90, in dependence on compression force, addition of two types of lubricants, and two active ingredients. The lubricants were magnesium stearate and sodium stearyl fumarate in a concentration of 0.5%, the active ingredients being ascorbic acid and acetylsalicylic acid in a concentration of 50%. Prosolv SMCC 90 proved to be better compatible than Prosolv HD 90; the compacts were of higher strength, which was markedly increased with increasing compression force. Prosolv HD 90 was more sensitive to additions of lubricants, and a greater decrease in strength was recorded due to the influence of sodium stearyl fumarate. The effect of lubricants on the strength of compacts in the presence of active ingredients was not identical. The disintegration time of compacts from Prosolv HD 90 without as well as with lubricants was shorter than from Prosolv SMCC 90 and was increasing with increasing compression force. Disintegration time was increased with added lubricants, and it was markedly shortened by addition of active ingredients. Compacts containing ascorbic acid possessed a shorter disintegration time than those containing acetylsalicylic acid, and it was not markedly influenced by the presence of lubricants.

Topics: Ascorbic Acid; Aspirin; Cellulose; Chemistry, Pharmaceutical; Excipients; Fumarates; Lubrication; Silicon Dioxide; Stearic Acids; Tablets; Technology, Pharmaceutical; Tensile Strength

Stearate-graphite paste electrodes (SGEs) exhibit enhanced dopamine sensitivity and insensivity to asorbic acid electrocatalytic effects in vitro following exposure to unidentified contituents of rat brain tissue homogenates. The present study utilized voltammetry and chronamperometry to compare the electrochemical characteristics of brain-treated SGEs to those treated with potential brain constituent candidates (albumin proteins and phospholipids). Albumin treatments markedly attenuated interference from ascorbate catalytic effects whereas lipids enhanced both electrode capacitance and sensitivity to dopamine. Combined treatments resulted in electrochemical properties that were similar to brain-treated SGEs. Potential mechanisms by which albumin may attenuate ascorbate electrocatalysis of dopamine were investigated using high performance liquid chromatography, with electrochemical detection. The reduction in ascorbate electrocatalytic effects at albumin-treated SGEs may be due to nucleophilic binding of dopamine oxidation products to albumin attached to the electrode surface. Therefore, the unambiguous detection of dopamine by SGEs in vivo may be related to interactions with factors in brain having similar surface-modifying properties.

Topics: Animals; Ascorbic Acid; Brain Chemistry; Catalysis; Dopamine; Electrochemistry; Electrodes; Evaluation Studies as Topic; Graphite; Hydroquinones; In Vitro Techniques; Phospholipids; Quinones; Rats; Serum Albumin, Bovine; Stearic Acids

The oxidation of low density lipoprotein (LDL) was carried out aiming specifically at elucidating the anti-oxidant action of alpha-tocopherol. Lipophilic and hydrophilic azo compounds and copper induced the oxidation of LDL similarly to give cholesterol ester and phosphatidylcholine hydroperoxides as major products. The antioxidant potency of alpha-tocopherol in LDL was much poorer than in homogeneous solution. Doxyl stearic acids were used as spin probe and incorporated in LDL. The rate of reduction of doxyl nitroxide in LDL by ascorbate decreased with increasing distance from the LDL surface. From the competition between the spin probe and alpha-tocopherol in scavenging radical, it was found that the efficacy of radical scavenging by alpha-tocopherol became smaller as the radical went deeper into the interior of LDL. On the other hand, 2,2,5,7,8-pentamethyl-6-chromal spared the spin label regardless of the position of nitroxide. The antioxidant activity of chromanols against LDL oxidation increased with decreasing length of isoprenoid side chain at the 2-position. All these results were interpreted by location and low mobility of alpha-tocopherol in LDL. The tocopherol mediated propagation was observed notably at low rate of radical flux, but this was suppressed by reductant such as ascorbic acid and ubiquinol.

Topics: Amidines; Antioxidants; Ascorbic Acid; Azo Compounds; Copper; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Humans; Lipoproteins, LDL; Nitriles; Oxidation-Reduction; Solutions; Stearic Acids; Ubiquinone; Vitamin E

It has been shown that lipid peroxides derived from polyunsaturated fatty acids (PUFAs) inhibit the proliferation of various cells. In the meantime, it has been suggested that oxidative stress is closely related to the developmental blockage of mammalian embryos cultured in vitro. In this study, we investigated the effects by various fatty acids on mouse embryo development in vitro, and the reversal of these effects by various antioxidants such as superoxide dismutase, ascorbic acid, alpha-tocopherol, uric acid, and ethylenediaminetetraacetic acid.. Pronuclear and two-cell stage mouse (ICR) embryos were cultured in Biggers-Whitten-Whittingham medium with 0.3% bovine serum albumin alone or complexed with one of the following fatty acids: palmitic, stearic, oleic, linoleic, linolenic, or arachidonic acid. We also measured the fluorescence emission of embryos in media containing various fatty acids in order to investigate the involvement of H2O2 or lipid peroxidation in embryo development.. Palmitic acid and PUFAs including linoleic acid inhibited the embryo development. The inhibitory effect of PUFAs was attenuated by adding antioxidants into the media, while the inhibitory effect of palmitic acid was not. Both pronuclear and two-cell stage embryos with PUFAs showed markedly more intensive emissions than those under other conditions.. These results suggest that lipid radicals can easily be generated in early stage embryos and that blastomeres are among the cells vulnerable to the damage by lipid peroxidation.

Topics: alpha-Linolenic Acid; Animals; Arachidonic Acid; Ascorbic Acid; Cell Division; Edetic Acid; Embryonic and Fetal Development; Fatty Acids; Female; Fluorescence; Hydrogen; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Mice; Mice, Inbred ICR; Oleic Acid; Oleic Acids; Palmitic Acid; Palmitic Acids; Stearic Acids; Superoxide Dismutase; Uric Acid; Vitamin E

In the studies described here rat liver microsomes containing labeled palmitic, stearic, oleic or linoleic acids were incubated with fatty acid binding protein (FABP) and the rate of removal of 14C-labeled fatty acids from the membrane by the soluble protein was measured using a model system. More unsaturated than saturated fatty acids were removed from native liver mircrosomes incubated with similar amounts of FABP. The in vitro peroxidation of microsomal membranes mediated by ascorbate-Fe++, modified its fatty acid composition with a considerable decrease of the peroxidizability index. These changes in the microsomes facilitated the removal of oleic and linoeic acids by FABP, but the removal of palmitic and stearic acids was not modified. This effect is proposed to result from a perturbation of membrane structure following peroxidation with release of free fatty acids from susceptible domains.

Topics: Animals; Ascorbic Acid; Carbon Radioisotopes; Carrier Proteins; Cell Fractionation; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; Fatty Acids, Nonesterified; Fatty Acids, Unsaturated; Kinetics; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Luminescent Measurements; Microsomes, Liver; Neoplasm Proteins; Nerve Tissue Proteins; Oleic Acid; Oleic Acids; Palmitic Acid; Palmitic Acids; Rats; Stearic Acids

Glutathione-S-transferase (GST) activity from human term placenta and human fetal liver towards 1-chloro-2,4-dinitrobenzene as the second substrate was significantly inhibited by the saturated fatty acids, stearic (SA) and palmitic (PA) acids and fatty acid esters, ascorbyl stearate (Asc-S) and ascorbyl palmitate (Asc-P). The nature of inhibition of human placental GST was competitive towards CDNB with Ki values of 3.1, 10.0, 13.5 and 18.5 microM for Asc-S, Asc-P, PA and SA, respectively. The inhibitory effect of Asc-S on human term placental GST was reversible. I50 values for Asc-S, Asc-P, SA and PA were 15, 45, 83 and 78 microM, respectively, for partially purified human fetal liver GSTs and 21, 6, 88 and 117 microM, respectively, for partially pure rat liver GSTs. The evidence suggests that Asc-S, Asc-P, SA and PA are potent inhibitors especially of the pi-class of GST.

Topics: Animals; Ascorbic Acid; Female; Fetus; Glutathione Transferase; Humans; Isoenzymes; Kinetics; Labor, Obstetric; Liver; Palmitic Acid; Palmitic Acids; Placenta; Pregnancy; Rats; Stearic Acids

The effects of a serial dilution of linoleic acid on human spermatozoa in whole semen was tested on 21 semen samples obtained from 11 normal volunteers. The minimal concentration of linoleic acid required to stop the movement of at least 75% of the moving sperm ranged from 1 to greater than 100 mg/dl. Fifteen of 21 (71%) of the semen samples were inhibited by added free fatty acids (FFA) concentrations that were less than or close to the physiologic concentration ranges of FFA in blood plasma (1 to 30 mg/dl). The immobilized sperm often formed aggregates similar to those formed by the action of autoantibodies against sperm cells. Preliminary studies conducted on a variety of other FFA have indicated that oleic acid (18/1) was less toxic than linoleic acid (18/2) and that linolenic acid (18/3) was more toxic than linoleic acid. The saturated FFA palmitic acid (16/0) and stearic acid (18/0) at concentrations up to 100 mg/dl showed little or no toxicity to sperm cells. It is suggested that FFA toxicity be included among physiologic factors that affect the motility and spontaneous aggregation of sperm cells.

Topics: alpha-Linolenic Acid; Ascorbic Acid; Fatty Acids, Nonesterified; Humans; Linoleic Acid; Linoleic Acids; Linolenic Acids; Male; Oleic Acid; Oleic Acids; Palmitic Acid; Palmitic Acids; Semen; Sperm Agglutination; Sperm Motility; Stearic Acids

Human erythrocytes were labeled with stearic acid spin labels, and no change was detected in membrane fluidity under hyperosmotic stress, going from isotonicity to about 3000 mOsm. Intact erythrocytes labeled with an androstane spin label and submitted to simulation of freezing show the onset of irreversible structural breakdown occurring in a saline solution at 2,000 mOsm. Ghosts labeled with maleimide spin label (4-maleimide-2,2,6,6-tetramethylpiperidinooxyl) when submitted to solutions of increasing osmolalities (pH 7.4), exhibit protein conformational changes that are irreversible after a simulated freeze-thaw cycle. After sonication of maleimide spin-labeled ghosts, membrane buried sulfhydryl groups become exposed. Such preparations showed behavior similar to the unsonicated when in saline hyperosmolal medium (pH 7.4). Such results suggest the ionic strength of the medium as the determining factor of the detected conformational changes. Maleimide spin-labeled ghosts in 300 mOsm saline solution (pH 7.4) were treated with ascorbic acid (spin destruction of nitroxides), and the kinetic analysis indicates that 65% of the labeled sites are located at the external interface of the membrane or in hydrophilic channels. Deformation and rearrangements of membrane components in solutions of increasing osmolalities apparently are related to protein conformational changes, on the outside surface of erythrocyte membranes, with a significant amount being structurally dissociated of lipids.

Topics: Androstanes; Ascorbic Acid; Cyclic N-Oxides; Erythrocyte Indices; Erythrocyte Membrane; Erythrocytes; Freezing; Humans; Membrane Proteins; Osmolar Concentration; Protein Conformation; Sonication; Spin Labels; Stearic Acids

Topics: Animals; Ascorbic Acid; Esters; Guinea Pigs; Pharmacology; Radiography; Research; Stearic Acids

Topics: Ascorbic Acid; Carbon Dioxide; Fatty Acids; Oxidation-Reduction; Palmitic Acids; Stearic Acids

Topics: Ascorbic Acid; Stearic Acids; Water