Mixture Of Palmitic Acids Research Articles

MiR-1224-5p Enhances Hepatic Lipogenesis by Targeting Adenosine Monophosphate-Activated Protein Kinase α1 in Male Mice.

MicroRNAs are potential therapeutic targets for metabolic diseases. Here, miR-1224-5p was highly expressed in the livers of mice fed a high-fat diet (HFD) and in obese (ob/ob) mice. To examine the potential role of miR-1224-5p, we constructed liver-specific adenoviral vectors expressing either an miR-1224-5p inhibitor sequence or miR-1224-5p mimic sequences. After tail-vein vector injection, HFD-fed mice were examined for expression of lipogenic genes. We found that miR-1224-5p inhibitors significantly attenuated hepatic lipogenesis and steatosis in HFD-fed mice, whereas miR-1224-5p mimicked promoted lipid accumulation in the liver of chow-fed C57BL/6 mice. Additional in vitro studies demonstrated that downregulation of miR-1224-5p in HepG2 and primary hepatocytes led to a reduction of cellular triglycerides after treatment with an oleic acid and palmitic acid mixture. Importantly, this study also identified adenosine monophosphate-activated protein kinase (AMPK)-α1 as a direct target of miR-1224-5p. miR-1224-5p binding to the 3' untranslated region of AMPKα1 suppressed expression of the AMPKα1 protein and its downstream molecules. Metformin, an activator of AMPK, also inhibited hepatic expression of miR-1224-5p. Together, these findings indicate that miR-1224-5p promotes hepatic lipogenesis by suppressing AMPKα1 expression and suggest that miR-1224-5p inhibitors warrant further investigation as potential therapeutic tools in the treatment of nonalcoholic fatty liver disease.

Solubilities of Palmitic Acid + Capsaicin in Supercritical Carbon Dioxide

Solubilities of a solid binary mixture of palmitic acid and capsaicin in supercritical carbon dioxide (CO2) are reported in this work. Measurements were carried out in a semiflow apparatus at 308.15 and 328.15 K, and pressures ranging from 10 to 35 MPa. Experiments were replicated at least three times in order to check for the repeatability. The suitability of this apparatus was verified by determining the solubility of naphthalene and of an equimolar solid binary mixture constituted by naphthalene and phenanthrene in supercritical CO2. Solubilities of naphthalene are available in the literature and our measurements were found to be in good agreement with those vast data sets. Additionally, the method proposed by Mendez-Santiago and Teja to test the self-consistency of experimental data was used. Regarding the solid mixture naphthalene + phenanthrene, our results also agree with some literature data. The palmitic acid + capsaicin mixture was also prepared equimolarly. Solubility of palmitic acid was highe...

Inhibition of cholinergic potentiation of insulin secretion from pancreatic islets by chronic elevation of glucose and fatty acids: Protection by casein kinase 2 inhibitor

ObjectivesChronic hyperlipidemia and hyperglycemia are characteristic features of type 2 diabetes (T2DM) that are thought to cause or contribute to β-cell dysfunction by “glucolipotoxicity.” Previously we have shown that acute treatment of pancreatic islets with fatty acids (FA) decreases acetylcholine-potentiated insulin secretion. This acetylcholine response is mediated by M3 muscarinic receptors, which play a key role in regulating β-cell function. Here we examine whether chronic FA exposure also inhibits acetylcholine-potentiated insulin secretion using mouse and human islets. MethodsIslets were cultured for 3 or 4 days at different glucose concentration with 0.5 mM palmitic acid (PA) or a 2:1 mixture of PA and oleic acid (OA) at 1% albumin (PA/BSA molar ratio 3.3). Afterwards, the response to glucose and acetylcholine were studied in perifusion experiments. ResultsFA-induced impairment of insulin secretion and Ca2+ signaling depended strongly on the glucose concentrations of the culture medium. PA and OA in combination reduced acetylcholine potentiation of insulin secretion more than PA alone, both in mouse and human islets, with no evidence of a protective role of OA. In contrast, lipotoxicity was not observed with islets cultured for 3 days in medium containing less than 1 mM glucose and a mixture of glutamine and leucine (7 mM each). High glucose and FAs reduced endoplasmic reticulum (ER) Ca2+ storage capacity; however, preserving ER Ca2+ by blocking the IP3 receptor with xestospongin C did not protect islets from glucolipotoxic effects on insulin secretion. In contrast, an inhibitor of casein kinase 2 (CK2) protected the glucose dependent acetylcholine potentiation of insulin secretion in mouse and human islets against glucolipotoxicity. ConclusionsThese results show that chronic FA treatment decreases acetylcholine potentiation of insulin secretion and that this effect is strictly glucose dependent and might involve CK2 phosphorylation of β-cell M3 muscarinic receptors.

Polystyrene microcapsules with palmitic-capric acid eutectic mixture as building thermal energy storage materials

In this study, palmitic acid (PA) and capric acid (CA) eutectic mixture was encapsulated in polystyrene (PS) capsules as new latent heat thermal energy storage (LHTES) material for building applications. Eutectic composition ratio of the mixture was determined experimentally. Microencapsulated eutectic mixtures (MEEMs) were prepared in homogenized emulsions in 3 different PS/(PA-CA) weight ratios. The synthesis reaction was found complete according to Fourier Transformed Infrared (FT-IR) Spectroscopy. The physical and physicochemical characteristics, thermal endurance limits and operating stability of MEEMs were investigated through differential scanning calorimetry, thermal gravimetry, and thermal conductivity, particle size distribution analysis, scanning electron microscopy, and polarized optical microscopy techniques. The onsets of melting of MEEMs were measured between 13.5 and 17.1°C as those of crystallization were between 16.9 and 17.9°C. The latent heats of melting of MEEMs were measured between 46.3 and 77.3J/g as those of crystallization were between −45.0 and −73.6J/g. As a result, a eutectic mixture of PA and CA was depicted for building heating cooling applications and successfully encapsulated in PS shell at different weight ratios.

Preparation and properties of films cast from mixtures of poly(vinyl alcohol) and submicron particles prepared from amylose-palmitic acid inclusion complexes.

The use of starch in polymer composites for film production has been studied for increasing biodegradability, improving film properties and reducing cost. In this study, submicron particles were prepared from amylose-sodium palmitate complexes both by rapidly cooling jet-cooked starch-palmitic acid mixtures and by acidifying solutions of starch-sodium palmitate complexes. Films were cast containing poly(vinyl alcohol) (PVOH) with up to 50% starch particles. Tensile strength decreased and Young's modulus increased with starch concentration, but percent elongations remained similar to controls regardless of preparation method or starch content. Microscopy showed particulate starch distribution in films made with rapidly cooled starch-palmitic acid particles but smooth, diffuse starch staining with acidified sodium palmitate complexes. The mild effects on tensile properties suggest that submicron starch particles prepared from amylose-palmitic acid complexes provide a useful, commercially viable approach for PVOH film modification.

Synergistic effects of zinc oxide nanoparticles and Fatty acids on toxicity to caco-2 cells.

Fatty acids exposure may increase sensitivity of intestinal epithelial cells to cytotoxic effects of zinc oxide (ZnO) nanoparticles (NPs). This study evaluated the synergistic effects of ZnO NPs and palmitic acid (PA) or free fatty acids (FFAs) mixture (oleic/PA 2:1) on toxicity to human colon epithelial (Caco-2) cells. The ZnO NPs exposure concentration dependently induced cytotoxicity to Caco-2 cells showing as reduced proliferation and activity measured by 3 different assays. PA exposure induced cytotoxicity, and coexposure to ZnO NPs and PA showed the largest cytotoxic effects. The presence of FFAs mixture did not affect the ZnO NPs-induced cytotoxicity. Filtration of freshly prepared suspension of NPs through a 0.45-µm pore size membrane significantly reduced the cytotoxicity, indicating a role of concentration or size of particles in cytotoxic effects. The ZnO NPs and PA coexposure induced production of mitochondrial reactive oxygen species (mROS) but not intracellular ROS production, whereas FFAs mixture exposure did not induce mROS and inhibited intracellular ROS. Both ZnO NPs and fatty acids (PA and FFAs mixture) promoted lysosomal destabilization, which was not correlated with cytotoxicity. These results indicated that PA can enhance ZnO NPs-induced cytotoxicity probably by the augmentation of mROS production, whereas FFAs mixture did not affect ROS production. Synergistic effects between ZnO NPs and fatty acids may be important when considering NPs toxicity via oral exposure.

Formation, stability, and pH sensitivity of free-floating, giant unilamellar vesicles using palmitic acid-cholesterol mixtures.

Despite the fact that palmitic acid (PA) and cholesterol (Chol) do not form fluid bilayers once hydrated individually, giant unilamellar vesicles (GUVs) were formed from a mixture of palmitic acid and cholesterol, 30/70 mol/mol. These free-floating GUVs were stable over weeks, did not aggregate and were shown to be highly stable in alkaline pH compared to conventional phospholipid-based GUVs. Acidic pH-triggered payload release from the GUVs was associated with the protonation state of palmitic acid that dictated the mixing lipid properties, thus affecting the stability of the fluid lamellar phase. The successful formation of PA-Chol GUVs reveals the possibility to create monoalkylated amphiphile-based GUVs with distinct pH stability/sensitivity.

Impact of interfacial cholesterol-anchored polyethylene glycol on sterol-rich non-phospholipid liposomes

HypothesisLiposomes made of single-chain amphiphiles and a large amount of sterols display several advantages including a limited permeability. In the present paper, we examine the possibility to prepare such non-phospholipid liposomes with interfacial polyethylene glycol (PEG) in order to improve their circulation in the blood stream. Cholesterol (Chol) was chosen as the PEG anchor. ExperimentsThe phase behavior of mixtures of palmitic acid (PA) and cholesterol including various proportions of PEGylated cholesterol (PEG-Chol) was characterized. In conditions leading to the formation of fluid bilayers, properties of the resulting liposomes were assessed. FindingsUp to 20mol% of PEGylated cholesterol could be introduced without significant perturbations in fluid bilayers made of PA and cholesterol. With 10mol% PEG-Chol, PA/Chol/PEG-Chol liposomes showed a very limited permeability to calcein and doxorubicin. Doxorubicin could be actively loaded in PA/Chol/PEG-Chol liposomes with a high drug loading efficiency and a high drug to lipid ratio. Pharmaco-kinetic experiments in rats indicated that interfacial PEG reduced the clearance of PA/Chol liposomes compared to the naked ones. However the lifetime of these non-phospholipid liposomes in the blood circulation was considerably shorter than that observed for control PEGylated phospholipid liposomes, a phenomenon associated with the negative interfacial charge of the PA/Chol/PEG-Chol liposomes.

Study on phase diagram of fatty acids mixtures to determine eutectic temperatures and the corresponding mixing proportions

This study was focused on preparation and characterization of fatty acid eutectic mixtures as phase change materials (PCMs). The four common fatty acids: stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) were selected as representative to prepare binary and ternary eutectic mixtures by heating-ultrasonic method. The melting points of LA–MA, LA–SA, SA–MA, SA–PA, MA–PA, LA–MA–SA, MA–SA–PA mixtures with varying combination proportions were determined and then analyzed by drawing the phase diagrams to determine the eutectic points and the corresponding mixing proportions. The results showed that the eutectic temperature of ternary fatty acids was lower than binary fatty acids’; ternary mixture possessed the same thermal properties with pseudo-binary mixture in both melting temperature and latent heat of phase change; the Schröeder-Van Laar equation can be taken as a basis for mixing proportion of pseudo-binary fatty acid and ternary fatty acid systems; the ternary eutectic point on the ternary phase diagram was just in the vicinity of a small triangle which was formed by the connection between the three vertices and the three eutectic points of binary fatty acid in the corresponding across flats. Moreover, ternary and pseudo-binary mixtures had advantage in energy conservation applications such as building heating/cooling and indoor temperature controlling especially when the temperature in need was low.

Kinetic study of the acidolysis of high oleic sunflower oil with stearic–palmitic acid mixtures catalysed by immobilised Rhizopus oryzae lipase

The acidolysis of high oleic sunflower oil (containing >70% triolein) with 11 different stearic–palmitic acid mixtures at an oil:acid ratio of 1:1.3 (w/w) has been performed using a 1,3 regiospecific lipase (Rhizopus oryzae), to produce specialised fats with a high disaturated triacylglycerol (TAG) content (∼40%). The final conversions corresponded well to predictions from a probability model. The variation of TAG composition with time was also measured to study the reaction kinetics. Initially, a reaction scheme was formulated allowing all possible acidolysis reactions of TAGs with stearic, palmitic and oleic fatty acids at the 1 and 3 TAG positions. It was found that a first order scheme produced good fits to data and that reactions involving stearic and palmitic reactions in equivalent positions produced very similar fitted rate constants. When these rate constants were constrained to be equal, acceptable fits were also obtained. As the acidolysis reactions occur via the formation of diacylglycerols (DAGs) by hydrolysis (7.1–10.9%), a further scheme was tested whereby all possible reactions involving DAGs were included (with equal rate constants for equivalent reactions with palmitic and stearic acid to limit the number of fit parameters). This produced only a small increase in goodness of fit. Assuming a single value of rate constant for all reactions produced poor fits.

Non-phospholipid liposomes with high sterol content display a very limited permeability

We demonstrate that it is possible to form non-phospholipid fluid bilayers in aqueous milieu with a mixture of palmitic acid (PA), cholesterol (Chol), and cholesterol sulfate (Schol) in a molar proportion of 30/28/42. These self-assemblies are shown to be bilayers in the liquid ordered phase. They are stable between pH 5 and 9. Over this pH range, the protonation/deprotonation of PA carboxylic group is observed but this change does not appear to alter the stability of these bilayers, a behavior contrasting with that observed for binary mixtures of PA/Chol, and PA/Schol. The multilamellar dispersions formed spontaneously from the PA/Chol/Schol mixture could be successfully extruded to form Large Unilamellar Vesicles (LUVs). These LUVs show interesting permeability properties, linked with their high sterol content. These non-phospholipid liposomes can sustain a pH gradient (pHinternal 8/pHexternal 6) 100 times longer than LUVs made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol, with a molar ratio of 60/40. Moreover, the non-phospholipid LUVs are shown to protect ascorbic acid from an oxidizing environment (1 mM iron(III)). Once entrapped in liposomes, ascorbic acid displays a degradation rate similar to that obtained in the absence of iron(III). These results show the possibility to form novel nanocontainers from a mixture of a monoalkylated amphiphile and sterols, with a good pH stability and showing interesting permeability properties.

Melt crystallization for refinement of triolein and palmitic acid mixture as a model waste oil for biodiesel fuel production

Melt crystallization using an annular vessel with two circular cylinders was applied to produce high-quality vegetable oil from waste oil. The inner cylinder was cooled at a constant rate and rotated, and the outer cylinder was heated at a constant temperature. The melt was solidified on the inner cylinder surface. The binary system of triolein and palmitic acid was used as the model waste oil. We measured the distribution coefficient of triolein. Suitable operation conditions were proposed to attain a high yield and a high purity of triolein from waste oil. The distribution coefficient correlated well with the theoretical equation derived on the basis of the “local lever rule” at the interface of the crystal layer and melt [1].

Synergistic Effects of Skeletal Isomerization on Oleic and Palmitic Acid Mixtures for the Reduction in Cloud Point of Their Methyl Esters

Biodiesel is composed of saturated and unsaturated fatty acid esters, both of which have significant effects on the cloud point of biodiesel. These two classes of fatty acids also react differently to isomerization reactions for cloud point improvement. This study examines the effects of isomerization and hydroisomerization on the two most common saturated and unsaturated fatty acids that make up vegetable oils, i.e., palmitic and oleic acids, respectively. The two fatty acids are placed under two different reactions and analyzed both separately and mixed for the cloud point improvement of their esters. The two reactions, isomerization and hydroisomerization, are run at 250 °C and 1 MPa H2 and at 300 °C and 4 MPa H2, respectively. Negative and positive results were shown, i.e., cis to trans isomerization, causing an increase in cloud point, and branching, causing a reduction in cloud point. A 7.5 °C reduction in cloud point is achieved on the esters of a 55:45 (%) oleic acid/palmitic acid ratio, showing that isomerization and hydroisomerization reactions can successfully lower the cloud point of a mixture of fatty acid methyl esters.

Chemical constituents from the endophytic fungus Annulohypoxylon squamulosum

Chemical investigation of the EtOAc-soluble fraction of the 95 % EtOH extract of rice fermented with the endophytic fungus Annulohypoxylon squamulosum (BCRC 34022) led to the isolation of a new y-lactone, 4-hentriacontyl-dihydrofuran-2-one (1), together with nine known compounds, taraxasterol (2), oleanolic acid (3), β-sitostenone (4), ergosta-4,6,8(14),22-tetraen-3-one (5), cinnamic acid (6), a mixture of palmitic acid (7) and stearic acid (8), octadecyl ferulate (9), and 4,5,4',5'-tetrahydroxy-1,1'-binaphthyl (10). Their structures were elucidated by spectroscopic analyses, including 1D- and 2D NMR experiments, and by ESI-MS. Other known compounds were identified by comparing their spectral data with literature data.

Secondary metabolites from the endophytic fungus Annulohypoxylon boveri var. microspora BCRC 34012

A chemical study on the n-BuOH-soluble fraction of the 95% EtOH extract of long-grain rice (Oryza sativa) fermented with the endophytic fungus Annulohypoxylon boveri var. microspora (BCRC 34012) has resulted in the isolation of one new natural azaphilone derivative, designated as annulohypoxyboverin (1) together with 12 known compounds, (3R,6R,7E)-3-hydroxy-4,7-megstigma-dien-9-one (2), α-tocopheryl quinone (3), isofraxidin (4), coumarin (5), cinnamic acid (6), a mixture of palmitic acid (7) and stearic acid (8), N-cis-feruloyltyramine (9), luteolin (10), kaempferol (11), kaempferitrin (12), and 4,5,4′,5′-tetrahydroxy-1,1′-binaphthyl (13). Annulohypoxyboverin (1) contains a dihydrobenzofuran-2,4-dione backbone, 1-hydroxyhexyl side chain, and one γ-lactone ring. Their structures were elucidated by spectroscopic analyses including 1D and 2D NMR experiments, and by HR-ESI-MS. The relative configuration of 1 was confirmed by NOESY experiment. Other known compounds were identified by comparing their spectral data with those of literature data.

PH-Triggered Release from Nonphospholipid LUVs Modulated by the pKa of the Included Fatty Acid

It has been shown that mixtures of palmitic acid (PA) and cholesterol (Chol) or cholesterol sulfate (Schol) can form fluid bilayers. These bilayers could be extruded using standard extrusion techniques to obtain nonphospholipid large unilamellar vesicles (LUVs). These LUVs displayed a very limited passive permeability, associated with their high sterol content (typically 70 mol %). In addition, they showed a pH-dependent behavior dictated by the electrostatic interfacial interactions, which are drastically modulated by the protonation state of PA. Interestingly, the LUVs prepared with cholesterol were stable at high pH and the release of the content could be triggered by a pH decrease (i.e., the protonation of PA). In contrast, the LUVs including Schol were stable at low pH and a pH increase (leading to the deprotonation of PA) would induce the release. In the present study, we demonstrate that the pH triggering the release in these two systems can be dictated in a predictable manner by selecting a fatty acid with an appropriate pK(a). The pK(a) of the fatty acids was modulated by the presence of an electro-withdrawing group (hydroxyl or fluoro) in the alpha position of the carboxylic function. The fatty acid protonation state is shown to be a critical factor for the modulation of the liposome permeability. The described systems display a remarkable versatility regarding the pH-sensitivity because the nature of the sterol controls the overall pH stability of the LUVs while the fatty acid pK(a) fine-tunes the pH-induced release. Therefore, it is possible to rationally design LUVs with controlled release at a specific pH; this original aspect is beneficial to the use of LUVs for encapsulation, vectorization, and controlled release of active agents.

Molecular dynamics simulation analyses of viral fusion peptides in membranes prone to phase transition: effects on membrane curvature, phase behavior and lipid-water interface destabilization

To gain insight into the atomistic details of membrane fusion induced by fusogenic peptides, molecular dynamic simulations of synthetic peptides, derived from viral fusion proteins, contained in lipid bilayers were performed. A 20 amino acid peptide from the N-terminus of the influenza HA fusion peptide (WT20) assumed the oblique orientation at the interface between water and the membrane made up of dipalmitoylphosphatidylcholine (DPPC)/palmitic acid (PA), as reported previously for different membranes. Simulations of WT20 embedded in bilayer membranes made up of dioleoylphos-phatidylethanolamine (DOPE) and DPPC/PA showed a positive curvature-inducing effect, whereas WT20 showed a negative curvature-inducing effect on a DPPC bilayer. In phase re-constitution analyses starting from a random mixture of DPPC, PA and water molecules, WT20 weakly stabilized an inverted hexagonal phase. In the latter analyses WT20 preferentially assumed a transmembrane orientation as opposed to the interfacial orientation, regardless of the phase to which the system settled (lamellar vs. inverted hexagonal). In another set of analyses using systems containing a water layer between the apposed DPPC/PA (and DOPE) monolayers, the behavior of WT20 during the formation of an intermembrane connection (or stalk) was examined. Comparison among the mutants supports a view that the oblique orientation of WT20 facilitates the perturbation of the lipid-water interface and the stalk formation. Taken together, these results imply that the influenza HA fusion peptide can have substantial effects on the membrane curvature and can assume a wide range of orientation/position in membranes depending on the local environment of the lipid/water system. Its movability and oblique orientation appear to be associated with its ability to perturb membrane/water interfaces.

Solubility and density measurements of palmitic acid in supercritical carbon dioxide + alcohol mixtures

Solubility data of palmitic acid (hexadecanoic acid) in supercritical carbon dioxide were measured in the pressure range from 10 to 25 MPa at temperatures of 313 and 318 K. Densities for this binary mixture in the homogeneous phase and at saturation conditions were measured in the same range of temperature. The influence of 3 and 6 mol% ethanol and 2-propanol as co-solvent on the solubility and density data for the CO 2 + palmitic acid mixture was also determined at 313 K. Measurements were carried out in a static-synthetic sapphire cell coupled to a vibrating-tube densitometer. The self-consistency of the data was tested according to the density-based models proposed by Mendez-Santiago and Teja.

Phase Separation of Palmitic Acid and Perfluorooctadecanoic Acid in Mixed Langmuir−Blodgett Monolayer Films

Deposition of mixtures of palmitic acid (C15H31COOH) and perfluorooctadecanoic acid (C17F35COOH) onto solid substrates gives rise to irregularly shaped, phase-separated domains under a variety of deposition conditions. The morphology and chemical composition of these phase-separated domains have been investigated using a combination of surface pressure-area isotherms, atomic force microscopy, X-ray photoemission electron microscopy, and confocal fluorescence microscopy imaging. While domain morphology and composition in 2D phase-separated mixed monolayer systems can typically be rationalized in terms of an interplay between line tension and dipole-dipole repulsion effects, it was found that for this system additional kinetic factors, including domain growth rates and the rate of dissolution of the fatty acid component into the aqueous subphase, also play a major role in controlling film properties. The potential importance of these effects for the controlled patterning of solid substrates is discussed.

Cationic Detergent/Sterol Mixtures Can Form Fluid Lamellar Phases and Stable Unilamellar Vesicles

In recent studies, it has been shown that mixtures of palmitic acid (PA), and cholesterol or cholesterol sulfate (Schol), in a PA/sterol molar ratio of 30/70 lead to the formation of liquid-ordered (lo) lamellar phases. The extrusion of these systems gave large unilamellar vesicles (LUVs) that displayed a very limited passive permeability, a property associated with their high sterol content. In this study, we showed that the formation of lo-phase bilayers was also possible when mixing a cationic detergent (cetylpyridinium chloride, CPC) and sterol in a 30/70 molar ratio. The existence of this phase was established using IR and 2H NMR spectroscopy. Moreover, 2H NMR allowed us to study the orientation and dynamics of CPC and cholesterol in these self-assemblies. The extrusion of the CPC/Schol bilayers leads to the formation of LUVs, and their passive permeability was found to be very limited, making them interesting candidates as nanovectors.