Unsaturated Fatty Acid Moieties Research Articles

Crystal structure of Staphylococcus aureus lipase complex with unsaturated petroselinic acid.

Staphylococcus aureus produces large amounts of toxins and virulence factors. In patients with underlying diseases or compromised immune systems, this bacterium can lead to severe infections and potentially death. In this study, the crystal structure of the complex of S. aureus lipase (SAL), which is involved in the growth of this bacterium, with petroselinic acid (PSA), an inhibitor of unsaturated fatty acids, was determined by X-ray crystallography. Recently, PSA was shown to inhibit S. aureus biofilm formation and the enzymatic activity of SAL. To further characterize the inhibitory mechanism, we determined the half-inhibitory concentration of SAL by PSA and the crystal structure of the complex. The IC50 of the inhibitory effect of PSA on SAL was 3.4 μm. SAL and PSA inhibitors were co-crystallized, and diffraction data sets were collected to 2.19 Å resolution at SPring-8 to determine the crystal structure and elucidate the detailed structural interactions. The results show that the fatty acid moiety of PSA is tightly bound to a hydrophobic pocket extending in two directions around the catalytic residue Ser116. Ser116 was also covalently bonded to the carbon of the unsaturated fatty acid moiety, and an oxyanion hole in SAL stabilized the electrons of the double bond. The difference in inhibitory activity between PSA and ester compounds revealed a structure-activity relationship between SAL and PSA. Additional research is required to further characterize the clinical potential of PSA.

Formation mechanisms of molecular compound in saturated‐unsaturated mixed‐acid triacylglycerols mixture systems and its edible applications

AbstractThe triacylglycerols (TAGs) containing saturated (Sat)‐unsaturated (U) fatty acid moieties (Sat‐U mixed acid TAGs) are widely present in most natural fats and employed in many industrial applications. The mixing behavior of different Sat‐U mixed acid TAGs acts important roles in the physicochemical properties TAG‐based materials. Among the three main mixing states of miscible, eutectic and molecular compound (MC) forming mixtures, fundamental research has been conducted on the MC crystals formed by different Sat‐U mixed acid TAGs to understand the structures, phase behavior and crystallization properties. This article reviews studies to date on the complex thermodynamic, kinetic and structural factors that affect the formation of MC crystals in binary and ternary mixtures of Sat‐U mixed acid TAGs (SatUSat, SatSatU, USatU and UUSat) through specific molecular interactions among the component TAGs. Furthermore, the application of the MC‐forming mixtures containing cacao butter to new types of cocoa butter alternative is reviewed.

Enantioselective synthesis and stereochemical determination of the highly reduced polyketide ishigamide.

Ishigamide was isolated as a metabolite of a recombinant strain of Streptomyces sp. MSC090213JE08 and its unsaturated fatty acid moiety has been confirmed in vitro to be synthesized by a type II PKS. Biosynthesis of such a highly reduced polyketide by a type II PKS is worthy of note. However, absolute configuration of ishigamide remained unknown. (R)-Ishigamide was synthesized enantioselectively employing Stille coupling and Wittig reaction between three units, vinyl iodide, stannyldienal, and Wittig salt. Stereochemistry of natural ishigamide was determined to be R by chiral HPLC analysis comparing with the synthesized standard.

The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity.

The natural peptide somatostatin has hormonal and cytostatic effects exerted by the binding to specific receptors in various tissues. Therapeutic uses are strongly prevented by its very short biological half-life of 1–2 min due to enzymatic hydrolysis, therefore encapsulation methodologies are explored to overcome the need for continuous infusion regimes. Multilamellar liposomes made of natural phosphatidylcholine were used for the incorporation of a mixture of somatostatin and sorbitol dissolved in citrate buffer at pH = 5. Lyophilization and reconstitution of the suspension were carried out, showing the flexibility of this preparation. Full characterization of this suspension was obtained as particle size, encapsulation efficiency and retarded release properties in aqueous medium and human plasma. Liposomal somatostatin incubated at 37 °C in the presence of Fe(II) and (III) salts were used as a biomimetic model of drug-cell membrane interaction, evidencing the free radical processes of peroxidation and isomerization that transform the unsaturated fatty acid moieties of the lipid vesicles. This study offers new insights into a liposomal delivery system and highlights molecular reactivity of sulfur-containing drugs with its carrier or biological membranes for pharmacological applications.

Drospirenone induces the accumulation of triacylglycerides in the fish hepatoma cell line, PLHC-1.

Drospirenone (DRO) is one of the most commonly used progestins reaching the aquatic environment through wastewater treatment plant effluents. It is a progesterone receptor agonist, and as such, can act primarily in the brain and reproductive organs of fish. In order to better understand and predict its effects, this work evaluates the lipidomic changes induced in PLHC-1 cells after exposure to drospirenone at concentrations below the EC10 (1 and 10 μM) by direct injection of the lipid extracts into a ESI(+/-) Orbitrap mass spectrometer. A significant accumulation of triacylglycerides, particularly long chain ones with unsaturated fatty acid moieties (TGs 46:2, 56:4-7; 58:5-8) and a concomitant decrease of diacylglycerides (DGs 32:1, 34:1-2, 36:1-2, 38:2-4) was observed after 48 h exposure to 10 μM DRO, which corresponded to an intracellular concentration of 8.3 ng·mg-1 protein. No significant alteration of PLHC-1 cell lipids was observed following exposure to 1 μM DRO. EC50 for the cytotoxicity of DRO ranged from 105 to 119 μM (24 h exposure) to 51-58 μM (48 h exposure). The study evidences a dysregulation of neutral lipid metabolism and increased TG/DG ratio in fish hepatic cells exposed to DRO.

Dual role of methyl-β-cyclodextrin in the emulsion polymerization of highly hydrophobic plant oil-based monomers with various unsaturations

Although series of latexes from plant oil-based acrylic monomers (POBMs) were recently synthesized in emulsion, two factors—allylic termination (the chain transfer reaction to the fatty acid double bonds) and the poor aqueous solubility of POBMs—lead to the lower total monomer conversion and molecular weight of the resulting latex polymers.In this study, amphiphilic oligosaccharide, methyl-β-cyclodextrin (M-β-CD), was used to improve the polymerizability of monomers from high oleic soybean (HO-SBM) and linseed (LSM) oil in copolymerization with styrene. Using X-ray diffractometry and differential scanning calorimetry, interactions between the monomers and M-β-CD were confirmed, while the formation of 1:1 complex from oligosaccharide and each monomer molecules was demonstrated by mass spectrometry.In the presence of “host-guest” complexes, polymer yield increases as the coagulum amount drops during the emulsion polymerization of both plant oil-based monomers with styrene indicating their enhanced aqueous solubility. Remarkably, latex polymers with a consistently higher molecular weight were obtained in the presence of M-β-CD. The complex formation and incorporation of monomer molecules into the oligosaccharide cavities protect the fatty acid moieties and diminishes chain transfer. The latter assumption was quantitatively confirmed in 1H NMR spectroscopy by determining the number of protons of the alkyl carbon−carbon double bonds (–CH = CH–) and the bisallylic hydrogen atoms (–CH = CH–CH2–CH = CH–) in the unsaturated fatty acid moieties of the latex copolymers. The observed effect is more pronounced for more unsaturated monomer from linseed oil.Based on the obtained results, M-β-CD plays a dual role in both enhancing POBM polymerizability as well as protecting against allylic termination chain transfer.

Water‐based polyurethane dispersions

AbstractA general overview is presented of the most relevant and commercially available aqueous polyurethane dispersions (PUDs) and their typical properties. This paper starts with the chemistry and the general composition of standard PUDs and subsequently urethane–acrylic hybrid dispersions are presented with special emphasis on the relation between the obtained morphology and the final material properties. In a section regarding crosslinkable PUDs, the two most frequently applied curing mechanisms are mentioned: firstly the introduction of carbonyl groups into PUDs which can be used for curing at room temperature with amino functional compounds by formation of azomethine moieties, and secondly the introduction of unsaturated fatty acid moieties into PUDs, which enable oxidative curing at ambient conditions. The paper then continues with a section on UV‐curable, acryloyl‐functional PUDs, followed by a section on an interesting new development, namely water‐based polyurethanes with special optic and haptic properties. The paper ends with a section on recently reported modifications of PUDs, including carbon nanotube‐ and graphene‐modified PUDs, PUDs modified with silane coupling agents and PUDs modified with biodegradable moieties. © 2018 Society of Chemical Industry

Polydimethylsiloxane Droplets Exhibit Extraordinarily High Antioxidative Effects in Deep-Frying.

The addition of more than about 1 ppm polydimethylsiloxane (PDMS) into oil results in PDMS forming both a layer at the oil-air interface and droplets suspended in the oil. It is widely accepted that the extraordinarily strong and stable antioxidative effects of PDMS are due to the PDMS layer. However, the PDMS layer showed no antioxidative effects when canola oil did not contain droplets but rather was covered with a layer of PDMS, then subjected to heating under high agitation to mimic deep-frying. Furthermore, no antioxidative effect was exhibited by oil-soluble methylphenylsiloxane (PMPS) in canola oil or by PDMS in PDMS-soluble canola oil fatty acid ester during heating, suggesting that PDMS must be insoluble and droplets in oil in order for PDMS to exhibit an antioxidative effect during deep-frying. The zeta potential of PDMS droplets suspended in canola oil was very high and thus the negatively charged PDMS droplets should attract nearby low molecular weight compounds. It was suggested that this attraction disturbed the motion of oxygen molecules and prevented their attack against unsaturated fatty acid moiety. This would be the reason in the deep-frying why PDMS suppressed the oxidation reaction of oil. PDMS droplets also attracted volatile compounds (molecular weight below 125 Da) generated by heating canola oil. Thus, adding PDMS to oil after heating the oil resulted in the heated oil smelling less than heated oil without PDMS.

The influence of polysorbate 80 on the radiochemical synthesis of a PET tracer in the FASTlab.

The aim of current study was to investigate the influence of a common non-ionic surfactant, polysorbate 80 (PS80), on radioactive labelling process of a novel PET tracer, [(18)F]Flutemetamol. Ferrous oxidation-xylenol orange (FOX) assay, in addition to UV/VIS and (1)H NMR spectroscopies were applied to characterise the composition of the PS80 solution after storage. Multivariate Curve Resolution (MCR) and PLS analysis was used to establish correlation between quality of the PS80 solution and the RCP obtained after labelling. The levels of unsaturated fatty acid moieties of PS80 were negatively correlated to RCP of [(18)F]Flutemetamol after synthesis. This explains the slight increase in RCP when stored PS80 solutions were applied in the synthesis. The mechanism behind this observation is suggested to be related to radiation induced radical formation in the unsaturated fatty acids, which subsequently causes instability of the PET tracer. UV/VIS spectroscopy was demonstrated to have the ability as a possible control tool for quality assurance of the studied radioactive labelling process. The presence of unsaturated fatty acid moieties in PS80 was found to be one of the most important factors responsible for the reduction in RCP of [(18)F]Flutemetamol after synthesis.

Chlorophyll a and chlorophyllide a inside liposomes made of saturated and unsaturated lipids: A possible impact of the lipids microenvironment

The aim of this work was to examine a possible impact of liposomes lipids microenvironment, dictated by a chemical composition of the fatty acid branches, on incorporation and spectral behaviour of chlorophyll a, and its derivative, chlorophyllide a inside small liposomes. The liposomes with the incorporated chlorophylls were made of dimirystoyl phosphatidylcholine (DMPC), and unsaturated phosphatidylcholine (PC), containing significant fractions of unsaturated fatty acid moieties. In order to achieve the goal, both absorption and fluorescence polarization spectroscopy were applied, and the obtained data for the two incorporated pigments, which play a role of molecular sensors, were compared. In addition, quercetin, a well-known antioxidant, was used as the (chlorophylls) emission quencher, in order to estimate the type of environment sensed by the two pigments for the two liposomes that differ in chemical composition. The results, based primarily on fluorescence polarization data have shown that the emissions as well as the emission quenching were notably affected by a change in the lipids? chemical composition. That is an indirect proof of the impact of the liposomes microenvironment on the incorporated pigments? spectral behaviour.

Banning toxic heavy-metal catalysts from paints: enzymatic cross-linking of alkyd resins

Alkyd resins are polyesters containing unsaturated fatty acids that are used as binding agents in paints and coatings. Chemical drying of these polyesters is based on heavy metal catalyzed cross-linking of the unsaturated fatty acid moieties. Among the heavy-metal catalysts, cobalt complexes are the most effective, yet they have been proven to be carcinogenic. Therefore, strategies to replace the cobalt-based catalyst by environmentally friendlier and less toxic alternatives are under development. Here, we demonstrate for the first time that a laccase–mediator system can effectively replace the heavy-metal catalyst and cross-link alkyd resins. Interestingly, the biocatalytic reaction does not only work in aqueous media, but also in a solid film, where enzyme diffusion is limited. Within the catalytic cycle, the mediator oxidizes the alkyd resin and is regenerated by the laccase, which is uniformly distributed within the drying film as evidenced by confocal laser scanning microscopy. During gradual build-up of molecular weight, there is a concomitant decrease of the oxygen content in the film. A new optical sensor to follow oxygen consumption during the cross-linking reaction was developed and validated with state of the art techniques. A remarkable feature is the low sample amount required, which allows faster screening of new catalysts.

Structure–activity relationships of siRNA carriers based on sequence-defined oligo (ethane amino) amides

Sequence defined oligo (ethane amino) amides produced by solid-phase supported synthesis using different building blocks and molecular shapes were tested for structure–activity relationships in siRNA delivery. Efficient reporter gene knockdown was obtained in a variety of cell lines using either branched three-armed structures, or lipid-modified structures with i-shape, T-shape, U-shape configuration. For the majority of structures (apart from U-shapes), the presence of 2 or 3 cysteines was strictly required for polyplex stabilization and silencing activity. Although all four building blocks contain the ethylenediamine proton sponge motif, only oligomers assembled with the tetraethylenepentamine based amino acids (Stp, Gtp, Ptp) but not with the triethylenetetramine based amino acid (Gtt) were able to mediate efficient gene silencing. For the lipopolymeric structures, out of the tested saturated (from C4 to C18) and unsaturated (C18) fatty acid moieties, two proximate oleic acids or linolic acids provided the oligomers with the best gene silencing activity and also pH specific lytic activity at pH 5.5, presumably facilitating endosomal escape of the polyplexes. Evaluation of oligomer chain length revealed a minimal number of at least two oligo (ethane amino) building blocks per oligomer arm as necessary for the vast majority of structures, but only marginal changes were found with higher numbers (structures with up to 60 ethane amino nitrogens were evaluated). Two promising carriers (T-shape 49, i-shape 229) were also evaluated for EG5 siRNA delivery. This resulted in tumor cell cycle arrest, and appearance of mitotic monoastral spindles both in vitro and in vivo upon systemic delivery. Repeated intratumoral treatment with EG5 siRNA polyplexes significantly reduced Neuro2A-eGFPLuc tumor growth in a siRNA-specific manner.

Separation of asymmetric triacylglycerols into their enantiomers by recycle high‐performance liquid chromatography

AbstractA recycle HPLC system equipped with a polysaccharide‐based chiral column was used for the enantiomeric separation of asymmetric triacylglycerols (TAGs). When the chiral columns were screened by the resolution of 1,2‐dipalmitoyl‐3‐oleoyl‐rac‐glycerol separation was achieved only with the cellulose tris‐ (3,5‐dimethylphenylcarbamate) chiral selector. The resolution of other TAG enantiomers was also examined, and 1,2‐dioleoyl‐3‐palmitoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐linoleoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐eicosapentaenoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐docosahexaenoyl‐rac‐glycerol, and 1,2‐docosahexaenoyl‐3‐palmitoyl‐rac‐glycerol were resolved into their respective enantiomers. However, neither 1,2‐dioleoyl‐3‐linoleoyl‐rac‐glycerol, consisting of only unsaturated fatty acids, nor 1,2‐dipalmitoyl‐3‐stearoyl‐rac‐glycerol, consisting of only saturated fatty acids, was resolved. In addition, 1,2‐eicosapentaenoyl‐3‐palmitoyl‐rac‐glycerol was not resolved clearly, even in the recycle runs. These results suggest that asymmetric TAGs having both a palmitic acid moiety and an unsaturated fatty acid moiety at the sn‐1 or sn‐3 positions might be resolved on a cellulose tris‐ (3,5‐dimethylphenylcarbamate) chiral column.

ChemInform Abstract: Synthesis of a Highly Unsaturated Fatty Acid Moiety of Lipo- Oligosaccharides Determining Host-Specificity in Rhizobium.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Effect of UVA or UVB Irradiation on Cutaneous Lipids in Films or in Solution

The barrier function of the skin is largely due to the stratum corneum which is essentially composed of lipids. Different external factors, such as UV irradiation, affect this skin layer and are responsible for a destabilization of the supramolecular organization of its constituted lipids. In this work, mass spectrometry and infrared spectroscopy are combined to study the correlation between the formation of oxidative compounds by UV irradiation and the lipid organization. Experiments were carried out on unsaturated lipids in film or solution form, exposed to UVA or UVB irradiation. UV exposure leads to the formation of oxygenated entities in the case of lipids with an unsaturated fatty acid moiety, resulting in a decrease in their packing which is greater when the lipids are in solution. The packing decrease is even greater following UVB irradiation.

Reactions of ozone with human skin lipids: Sources of carbonyls, dicarbonyls, and hydroxycarbonyls in indoor air

This study has used proton transfer reaction-mass spectrometry (PTR-MS) for direct air analyses of volatile products resulting from the reactions of ozone with human skin lipids. An initial series of small-scale in vitro and in vivo experiments were followed by experiments conducted with human subjects in a simulated office. The latter were conducted using realistic ozone mixing ratios (approximately 15 ppb with occupants present). Detected products included mono- and bifunctional compounds that contain carbonyl, carboxyl, or alpha-hydroxy ketone groups. Among these, three previously unreported dicarbonyls have been identified, and two previously unreported alpha-hydroxy ketones have been tentatively identified. The compounds detected in this study (excepting acetone) have been overlooked in surveys of indoor pollutants, reflecting the limitations of the analytical methods routinely used to monitor indoor air. The results are fully consistent with the Criegee mechanism for ozone reacting with squalene, the single most abundant unsaturated constituent of skin lipids, and several unsaturated fatty acid moieties in their free or esterified forms. Quantitative product analysis confirms that squalene is the major scavenger of ozone at the interface between room air and the human envelope. Reactions between ozone and human skin lipids reduce the mixing ratio of ozone in indoor air, but concomitantly increase the mixing ratios of volatile products and, presumably, skin surface concentrations of less volatile products. Some of the volatile products, especially the dicarbonyls, may be respiratory irritants. Some of the less volatile products may be skin irritants.

Synthesis and Structure of Mycolactone E Isolated from Frog Mycobacterium

The structure of mycolactone E, isolated from the frog pathogen Mycobacterium liflandii, was established via organic synthesis. Within the mycolactone family of metabolites, a structural variation has been seen only at the unsaturated fatty acid moiety thus far, and mycolactone E follows this observation. Interestingly, the absolute configuration of its unsaturated fatty acid matches that of the mycolactones from human mycobacteria, rather than the structurally more closely related mycolactone F from fish mycobacteria.

Biodegradable honeycomb-patterned film composed of poly(lactic acid) and dioleoylphosphatidylethanolamine

Honeycomb-patterned films have been reported to be useful for scaffolds of cell culture in tissue engineering. In the present study, we investigated a new compound, dioleoylphosphatidylethanolamine (DOPE), a naturally derived phospholipid having unsaturated fatty acid moieties, as a surfactant for fabricating honeycomb-patterned poly( d, l-lactide) (PLA) film. Only DOPE among commercially available phospholipids was useful as a surfactant, and it showed good solubility in PLA/chloroform solution and an excellent property for fabricating honeycomb-patterned film (the concentration of DOPE was from 0.2% to 20% by weight based on the weight of PLA). The pore size of the honeycomb was uniform, and all pores were interconnected with each other. The contact angle of water on the honeycomb-patterned film was affected by the amount of DOPE. Time-of-flight secondary ion mass spectrometer (TOF-SIMS) data suggested that DOPE was concentrated on the surface of the honeycomb-patterned film. To investigate cell proliferation and adhesion on the honeycomb-patterned film, NIH3T3 fibroblast cells were cultured on the film. The NIH3T3 cells adhered well on the honeycomb-patterned PLA film with DOPE (PLA–DOPE) and showed good cell proliferation compared to that on honeycomb-patterned PLA film fabricated with a copolymer (CAP) of dodecylacrylamide and ω -carboxyhexylacrylamide (PLA–CAP). These results suggest that the honeycomb-patterned PLA–DOPE can be applicable as a scaffold for cells with better profiles in comparison with PLA–CAP.

Enzymatic synthesis and curing of biodegradable epoxide-containing polyesters from renewable resources.

Epoxide-containing polyesters were enzymatically synthesized via two routes using unsaturated fatty acids as starting substrate. Lipase catalysis was used for both polycondensation and epoxidation of the unsaturated fatty acid group. One route was synthesis of aliphatic polyesters containing an unsaturated group in the side chain from divinyl sebacate, glycerol, and the unsaturated fatty acids, followed by an epoxidation of the unsaturated fatty acid moiety in the side chain of the resulting polymer. In another route, epoxidized fatty acids were prepared from the unsaturated fatty acids and hydrogen peroxide in the presence of lipase catalyst, and subsequently the epoxidized fatty acids were polymerized with divinyl sebacate and glycerol. The polymer structure was confirmed by NMR and IR, and for both routes, the high epoxidized ratio was achieved. Curing of the resulting polymers proceeded thermally, yielding transparent polymeric films with high gloss surface. Pencil scratch hardness of the present films improved, compared with that of the cured film obtained from the polyester having an unsaturated fatty acid in the side chain. The obtained film showed good biodegradability, evaluated by BOD measurement in an activated sludge.

Enzymatic synthesis and curing of biodegradable crosslinkable polyesters

The lipase-catalyzed synthesis and curing of polyesters that possess an unsaturated fatty acid moiety in the side chain is described. Lipase-catalyzed polymerization of divinyl sebacate and glycerol in the presence of unsaturated fatty acids produced a crosslinkable polyester possessing the unsaturated group. Candida antarctica lipase showed high catalytic activity for their synthesis. Effects of reaction parameters, such as enzyme amount, temperature, and feed ratio of substrates, have been systematically investigated. The polymerization under reduced pressure improved the polymer yield and molecular weight. Divinyl adipate was also enzymatically polymerized with glycerol and linoleic acid to give the crosslinkable polyester. The polymer obtained using linoleic or linolenic acid, was cured using a cobalt naphthenate catalyst or thermal treatment to give a crosslinked, transparent, polymeric film with a high-gloss surface. The cured film was characterized by pencil-scratch hardness testing and FT-IR spectroscopy. The biodegradability of the obtained film was evaluated by biochemical oxygen demand (BOD) measurement in an activated sludge.