Saturated Hydrocarbon Chains Research Articles

Wettability transition on micro-nano hierarchical structured Ni20Cr coating surface by selective spontaneous adsorption during vacuum evacuation

A coating surface of metallic Ni20Cr with a bionic hierarchical micro-nano scaled structure was fabricated by shrouded plasma spraying technology. A novel phenomenon was found on the coating surface that the surface wettability can change from original super-hydrophilicity to super-hydrophobicity with a contact angle of 152° and sliding angle of 2° by evacuation in oil-free vacuum systems. To clarify the wettability transition mechanism in vacuum conditions, the microstructure and chemical composition of the coating surface were systematically investigated. The results revealed that the main reason for the wettability transition was due to the formation of chemisorbed carboxylates and physisorbed saturated hydrocarbons on the coating surface by selective spontaneous adsorption of the residual gas molecules from vacuum environment. The hydrophobic saturated hydrocarbon chains oriented outward the surface effectively reduced the surface energy and cause a spontaneous wettability transition. The evacuation process under the vacuum conditions enhanced the adsorption rate on the coating surface. The degree of wettability transition depended on the amount of the surface adsorbates.

Covalent immobilization of cytochrome P450 BM3 (R966D/W1046S) on glutaraldehyde activated SPIONs

AbstractSelective hydroxylation of the C‐H bond of saturated hydrocarbon chains at room temperature is the signature of an invaluable biocatalyst, cytochrome P450 BM3 from Bacillus megaterium. Despite this remarkable ability, because of the enzyme's inherent low stability and dependence on electron supply by expensive NADPH, developing stable and economic BM3 systems is a challenging subject. To improve BM3 stability, facilitate its reuse, and reduce the process cost, this study suggests covalent immobilization of R966D/W1046S P450 BM3 on glutaraldehyde pre‐activated super paramagnetic iron oxide nanoparticles (SPIONs). This double mutant consumes less expensive cofactors like NADH and BNAH and its immobilization on magnetic support facilitates its separation and reuse. Free and immobilized enzyme performances were evaluated by 10‐pNCA hydroxylation and BM3 selectivity (hydroxylation at ω (1–3) positions of a fatty acid) was confirmed in a reaction involving myristic acid. The enzyme activity recovery was up to 60 % with 100 % enzyme binding efficiency. BM3‐SPIONs were easily separated from the reaction medium by applying a magnet, and recycled for 5 times, after which they could still present half of their initial activity. The enzyme storage stability was significantly improved: after one month of storage at 4 °C, the immobilized enzyme showed 80 % residual activity toward NADH while the soluble enzyme was inactive after a week. Binding an enzyme to fabricated SPIONs is a promising technique to increase enzyme stability and prevent downstream contamination in biocatalytic processes. In this context, BM3‐SPIONs can be a practical model system in cost‐effective large‐scale applications of such enzymes.

Synthesis, characterization and antibacterial activity of novel heterocyclic quaternary ammonium surfactants

Abstract This work reports two new classes of non-toxic heterocyclic quaternary ammonium surfactants (HQASs) synthesized by condensation of a series of fatty acids with 2-morpholinoethan-1-amine and pyridin-4-ylmethanamine, followed by quaternization with benzyl bromide. Their critical micelle concentration (CMC), Krafft temperature ( Tk ), emulsion stability and foaming properties were determined. The CMC values of HQASs ranged from 0.24 to 0.55 mM/L. In vitro antibacterial activity studies revealed that the HQASs possessing unsaturated hydrocarbon chains exhibited activity against all the tested bacteria (minimum inhibitory concentration = 31.25–500 μg/mL) whereas, those possessing saturated hydrocarbon chains did not exhibit any activity.

ChemInform Abstract: Asymmetric Total Synthesis of Heronamides A—C: Stereochemical Confirmation and Impact of Long‐Range Stereochemical Communication on the Biological Activity.

Heronamides are biosynthetically related metabolites isolated from marine-derived actinomycetes. Heronamide C shows potent antifungal activity by targeting membrane phospholipids possessing saturated hydrocarbon chains with as-yet-unrevealed modes of action. In spite of their curious hypothesized biosynthesis and fascinating biological activities, there have been conflicts in regard to the reported stereochemistries of heronamides. Here, we describe the asymmetric total synthesis of the originally proposed and revised structures of heronamide C, which unambiguously confirmed the chemical structure of this molecule. We also demonstrated nonenzymatic synthesis of heronamides A and B from heronamide C, which not only proved the postulated biosynthesis, but also confirmed the correct structures of heronamides A and B. Investigation of the structure-activity relationship of synthetic and natural heronamides revealed the importance of both long-range stereochemical communication and the 20-membered macrolactam ring for the biological activity of these compounds.

Asymmetric Total Synthesis of Heronamides A-C: Stereochemical Confirmation and Impact of Long-Range Stereochemical Communication on the Biological Activity.

Heronamides are biosynthetically related metabolites isolated from marine-derived actinomycetes. Heronamide C shows potent antifungal activity by targeting membrane phospholipids possessing saturated hydrocarbon chains with as-yet-unrevealed modes of action. In spite of their curious hypothesized biosynthesis and fascinating biological activities, there have been conflicts in regard to the reported stereochemistries of heronamides. Here, we describe the asymmetric total synthesis of the originally proposed and revised structures of heronamide C, which unambiguously confirmed the chemical structure of this molecule. We also demonstrated nonenzymatic synthesis of heronamides A and B from heronamide C, which not only proved the postulated biosynthesis, but also confirmed the correct structures of heronamides A and B. Investigation of the structure-activity relationship of synthetic and natural heronamides revealed the importance of both long-range stereochemical communication and the 20-membered macrolactam ring for the biological activity of these compounds.

Theoretical studies on the electronic properties of alkyl chains

The charge transfer of the alkyl chains was studied by density functional theory calculations at the B3LYP/6-311++G∗∗ level. Two different series of the saturated hydrocarbon chains, CnH2n+1OH (n=10, 12, 14, 16, 18) and C12H25X (X=–Cl, –OH, –NH2) were considered for examining the effects of the chain length as well as the end group on the charge transfer properties of the alkyl chains. Computational results show that end group plays a key role on the electronic structures (HOMO–LUMO gap) of the saturated hydrocarbon chains, while the effect of the chain length on the conductive character of the alkyl chain is negligible. This is consistent with our previous experimental results. Further mechanism analysis of the charge transfer in saturated hydrocarbon chains indicates that HOMO–LUMO gap values depend strongly on the adiabatic ionization potentials (AIPs). Moreover, detailed spin density distribution analysis shows the radical cationic state is localized on the transport channel of the molecular orbital used for charge transfer.

Langmuir films and mechanical properties of polyethyleneglycol fatty acid esters at the air-water interface

Abstract Polyethylene glycol (PEG) fatty acid esters are used in various industries for their interfacial properties, especially because their emulsifying characteristics can be varied considerably by altering the size of the PEG or fatty acid chains. In this study, we combine experimental surface-specific methods and molecular dynamics (MD) simulations to probe the effects from changing both the hydrophilic and hydrophobic chain sizes. PEG fatty acids containing either stearic or palmitic acid ethoxylated PEG chains of average molecular weight 200 or 400 g mol −1 (referred to as PEG200 and PEG400, respectively) had critical aggregation concentrations between 30 and 50 μM, and formed Langmuir films at the air/water interface with compressibility modulus typical of liquid-expanded phases. The area per molecule was consistently smaller for the PEG200 series owing to an increased ordering of the hydrophilic chains inferred from the polarization-modulated infrared reflection absorption (PM-IRRAS) spectra, which was corroborated by MD simulations. With PM-IRRAS and MD simulations, we also noted that the hydrophobic chain had increased order when its size increased from palmitic to stearic acid, which was attributed to a higher melting temperature for longer saturated hydrocarbon chains.

Carbamate-linked cationic lipids with different hydrocarbon chains for gene delivery

A series of carbamate-linked cationic lipids containing saturated or unsaturated hydrocarbon chains and quaternary ammonium head were designed and synthesized. After recrystallization, carbamate-linked cationic lipids with high purity (over 95%) were obtained. The structures of these lipids were proved by IR spectrum, HR-ESI-MS, HPLC, 1H NMR and 13C NMR. The liposomes were prepared by using these cationic lipids and neutral lipid DOPE. Particle size and zeta-potential were studied to show that they were suitable for gene transfection. The DNA-bonding ability of C12:0, C14:0 and C18:1 cationic liposomes was much better than others. The results of transfection showed that hydrophobic chains of these lipids have great effects on their transfection activity. The lipids bearing C12:0, C14:0 saturated chains or C18:1 unsaturated chain showed relatively higher transfection efficiency and lower cytotoxicity. So these cationic lipids could be used as non-viral gene carriers for further studies.

Syntheses of cardanol-based cationic surfactants and their use in emulsion polymerisation

AbstractSix quaternary ammonium salts were designed and synthesised with moderate to high yields in three steps, based on cardanol, a low-cost and abundant renewable resource. The new ammonium salts can act as reactive surfactants due to their having both a hydrophilic ammonium group and a hydrophobic unsaturated alkyl chain. The gemini surfactants with a linker of a linear saturated aliphatic hydrocarbon chain exhibited a relatively low CMC value(≤ 0.2 mmol L

Preparation, Physicochemical Properties, and Transfection Activities of Tartaric Acid-Based Cationic Lipids as Effective Nonviral Gene Delivery Vectors.

In this work two novel cationic lipids using natural tartaric acid as linking backbone were synthesized. These cationic lipids were simply constructed by tartaric acid backbone using head group 6-aminocaproic acid and saturated hydrocarbon chains dodecanol (T-C12-AH) or hexadecanol (T-C16-AH). The physicochemical properties, gel electrophoresis, transfection activities, and cytotoxicity of cationic liposomes were tested. The optimum formulation for T-C12-AH and T-C16-AH was at cationic lipid/dioleoylphosphatidylethanolamine (DOPE) molar ratio of 1 : 0.5 and 1 : 2, respectively, and N/P charge molar ratio of 1 : 1 and 1 : 1, respectively. Under optimized conditions, T-C12-AH and T-C16-AH showed effective gene transfection capabilities, superior or comparable to that of commercially available transfecting reagent 3β-[N-(N',N'-dimethylaminoethyl)carbamoyl]cholesterol (DC-Chol) and N-[2,3-dioleoyloxypropyl]-N,N,N-trimethylammonium chloride (DOTAP). The results demonstrated that the two novel tartaric acid-based cationic lipids exhibited low toxicity and efficient transfection performance, offering an excellent prospect as nonviral vectors for gene delivery.

Evaluation of ethephon induced oxidative stress to gonadal disorder and its amelioration by ethanolic extract of shoot of Bambusa balcooa Roxb. in Albino rat

Polyethylene glycol (PEG) fatty acid esters are used in various industries for their interfacial properties, especially because their emulsifying characteristics can be varied considerably by altering the size of the PEG or fatty acid chains. In this study, we combine experimental surface-specific methods and molecular dynamics (MD) simulations to probe the effects from changing both the hydrophilic and hydrophobic chain sizes. PEG fatty acids containing either stearic or palmitic acid ethoxylated PEG chains of average molecular weight 200 or 400 g mol−1 (referred to as PEG200 and PEG400, respectively) had critical aggregation concentrations between 30 and 50 μM, and formed Langmuir films at the air/water interface with compressibility modulus typical of liquid-expanded phases. The area per molecule was consistently smaller for the PEG200 series owing to an increased ordering of the hydrophilic chains inferred from the polarization-modulated infrared reflection absorption (PM-IRRAS) spectra, which was corroborated by MD simulations. With PM-IRRAS and MD simulations, we also noted that the hydrophobic chain had increased order when its size increased from palmitic to stearic acid, which was attributed to a higher melting temperature for longer saturated hydrocarbon chains.

Branched chain fatty acids concentrate prepared from butter oil via urea adduction

Saturated branched chain fatty acids (BCFA) intake in the US is greater than that of other bioactive fatty acids (FA), yet little information is available on methodologies to concentrate them. We report here the effect of urea‐to‐FA (urea:FA) ratio, adduction time, and temperature on the enrichment of branched chain fatty acids (BCFA) from butter oil. Urea adducts precipitate both saturated and monounsaturated hydrocarbon chains as urea complexes, leaving solubilized polyunsaturated FA and BCFA in the non‐urea adduct fraction (NUA). The optimum urea:FA ratio was found to be 4:1 and the optimum temperature to be 4°C. Adduction time had negligible effect on BCFA enrichment. Anteiso‐15:0 was most enriched across major BCFA under all conditions of temperature, time, and urea:FA ratio studied. In our preferred embodiment, a two‐stage urea adduction procedure applied to hydrolyzed butter oil resulted in an enrichment from <2% BCFA in the starting oil to >11% BCFA, indicating an enrichment factor of >6. The best method has a first stage performed at 4°C and urea:FA ratio of 4:1, and a second stage at 30°C and lower urea:FA ratio (2:1). Overall yield of BCFA in enriched fraction was about 10% of starting BCFA for two stages.Practical applications: BCFA are constituents of the GI tract of healthy newborns and are known to prevent necrotizing enterocolitis. The average per capita BCFA intake of Americans is estimated to be about 220 mg/day from dairy whereas based on the current dietary recommendations of USDA it should be about 400 mg/day from dairy alone with total amounting to 575 mg/day including beef. Using the results of the current study, enriched BCFA concentrates can be prepared to meet the demand.Enrichment in major branched chain fatty acids (BCFA) of butter oil after two stage urea adduction. First stage (NUA‐1) and second stage (NUA‐2) were conducted using 4:1; 4°C 2 h and 2:1, 30°C 2 h of urea‐to‐fatty acids ratio (wt/wt), temperature and time of adduction, respectively.

Oxovanadium(IV) complexes based on S-alkyl-thiosemicarbazidato ligands. Synthesis, characterization, electrochemical, and antioxidant studies

Reaction of VOSO4 with 2-hydroxy-napthaldeyde-S-R-thiosemicarbazones (R: methyl, ethyl, propyl or allyl) and salicyl aldehyde yielded five-coordinate oxovanadium(IV) complexes having a N1,N4-diarylidene-S-R-thiosemicarbazidato structures. The compounds were characterized by elemental analysis, magnetic measurements, electronic, infrared, 1H-NMR, and electron paramagnetic resonance (EPR) spectra. The X-band EPR signals were recorded from powder forms and also in solution. All the complexes have a single asymmetric line shape and theoretical fit studies prove the presence of axial symmetry around the paramagnetic vanadium ions. A computer simulation of the EPR spectrum of each complex was carried out to derive the related EPR parameters. Cyclic voltammograms of the complexes exhibited two metal-based reversible redox peaks around 500 and −800 mV corresponding to one electron oxidation/reduction of VIVO/VVO and VIVO/VIIIO, respectively. The reductive response in the 50–350 mV region was assigned to ligand reduction. Antioxidant activities of the compounds were determined with CUPric Reducing Antioxidant Capacity, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, and 1,1-diphenyl-2-picrylhydrazyl assays. The test results indicated that the antioxidant capacity of the compounds increases with the carbon number of saturated hydrocarbon chain on sulfur atom.

Stepping between Membrane Microdomains

Lateral membrane microdomains are postulated to be involved in a number of important functions in mammalian cells, such as membrane trafficking, exocytosis, endocytosis, signal transduction, and protein activity (1,2). These putative cell microdomains have been the subject of extensive research using a variety of biophysical and biochemical techniques, including detergent extraction (2), fluorescence microscopy (3), electron microscopy (4), fluorescence resonance energy transfer microscopy (5), fluorescence correlation spectroscopy (6), fluorescence recovery after photobleaching (7), and single-molecule tracking (8).

Nanoscale Structure and Dynamics of the Liquid Ordered Phase

Nanoscale Structure and Dynamics of the Liquid Ordered PhaseWe report the detailed structure and dynamics of ternary mixtures of lipids and cholesterol on the ten microsecond timescale, obtained by all-atom simulation on the Anton supercomputer.1 Using the CHARMM36 force field and an analysis based on a hidden Markov model, we find excellent agreement between 2H NMR quadrupolar spectra for a mixture of DPPC/DOPC/Chol with regions of liquid-ordered (Lo) and liquid-disordered lipids. The Lo phase is found to be heterogeneous on the nanoscale, comprising regions of hexagonally packed saturated hydrocarbon chains (red) and interstitial regions enriched in cholesterol (yellow) and unsaturated chains (blue). The dynamics are slow and collective, yielding sublinear scaling of lipid mean-squared displacements in Lo. Comparison to Lo phases formed by sphingomyelin reveals much stronger lipid-lipid interactions and consequently even slower dynamics. The hexagonal substructure within Lo is hypothesized to control partitioning of transmembrane segments between Lo and Ld, shedding new light on an old question: What is the difference between the Lo phase in lipid bilayers and raft-like regions in the plasma membrane?[1] Sodt, A. et al, J. Am. Chem. Soc. 136:725-732(2014).

ChemInform Abstract: Structure and Biological Activity of 8‐Deoxyheronamide C from a Marine‐Derived Streptomyces sp.: Heronamides Target Saturated Hydrocarbon Chains in Lipid Membranes.

AbstractTitle compound (I), a new 20‐membered polyene macrolactam, is a unique membrane binder.

Structure and Biological Activity of 8-Deoxyheronamide C from a Marine-Derived Streptomyces sp.: Heronamides Target Saturated Hydrocarbon Chains in Lipid Membranes

Polyene macrolactams are a class of microbial metabolites, many of which show potent biological activities with unidentified modes of action. Here we report that 8-deoxyheronamide C, a new 20-membered polyene macrolactam from a marine-derived actinomycete Streptomyces sp., is a unique membrane binder. 8-Deoxyheronamide C showed a characteristic sensitivity profile against fission yeast sterol mutant cells, indicating that the metabolite targets cell membranes. We detected tight physical interaction between heronamides including 8-deoxyheronamide C and heronamide C and saturated hydrocarbon chains in lipid membranes using surface plasmon resonance experiments. We further show that heronamides induced abnormal cell wall morphology in fission yeast probably by perturbing the structure of membrane microdomains. This work will accelerate the biological and medical investigation of polyene macrolactams.

The Molecular Structure of the Liquid-Ordered Phase of Lipid Bilayers

Molecular dynamics simulations reveal substructures within the liquid-ordered phase of lipid bilayers. These substructures, identified in a 10 μs all-atom trajectory of liquid-ordered/liquid-disordered coexistence (L(o)/L(d)) are composed of saturated hydrocarbon chains packed with local hexagonal order and separated by interstitial regions enriched in cholesterol and unsaturated chains. Lipid hydrocarbon chain order parameters calculated from the L(o) phase are in excellent agreement with (2)H NMR measurements; the local hexagonal packing is also consistent with (1)H-MAS NMR spectra of the L(o) phase, NMR diffusion experiments, and small-angle X-ray and neutron scattering. The balance of cholesterol-rich to local hexagonal order is proposed to control the partitioning of membrane components into the L(o) regions. The latter have been frequently associated with formation of so-called rafts, platforms in the plasma membranes of cells that facilitate interaction between components of signaling pathways.

Alkylresorcinols in rye (Secale cereale L.) grains. V. Chromatographic analysis of 5-n-alk(en)ylresorcinols during their preparation

Analysis of 5-n-alk(en)ylresorcinols during the coarse of their preparation from rye grains showed that changes of the composition of 5-n-alkylresorcinol homologues in acetone oil; raw preparation, and alkylresorcinol fraiction obtained after chromatography on silica gel, were insignificant. About 20% of alk(en)-ylresorcinals were washed out from acetone oil with pentane. Over 50% of alk(en)ylresorcinols eluted by pentane constituted homologues with unsaturated hydrocarbon chains (5-n-alkenylresorcinols). Preparation obtained after chromatagraphic separation constituted a mixtureof 5-n-alk(en)ylresorcinols width saturated hydrocarbon chains (5-n-alkylresorcinols).

The Molecular Structure of the Liquid Ordered Phase

Substructure within the liquid-ordered phase of lipid bilayers is reported, composed of saturated hydrocarbon chains packed with local hexagonal order, separated by interstitial regions enriched in cholesterol and unsaturated chains. The structure, identified during 10 μsec all-atom molecular dynamics simulation of liquid-ordered/liquid-disordered coexistence (Lo/Ld), is confirmed by comparison to 2H NMR quadropolar splittings. The balance of cholesterol-rich to local hexagonal order is proposed to control the partitioning of membrane components into the Lo region. Understanding how mechanisms present in the cell membrane _ such as crowding or coupling to the cytoskeleton _ shift the balance of cholesterol rich substructure should help resolve partitioning in bilayers and cell membranes.