Oleoyl Chains Research Articles

Design, Synthesis, and Tribological Behavior of an Eco-Friendly Methylbenzotriazole-Amide Derivative

Recently, researchers have been committed to boosting the environmental friendliness and functional performance of multifunctional additives. In this study, an eco-friendly methylbenzotriazole-amide derivative (MeBz-2-C18) was designed and synthesized, with ethylamine serving as the linkage between methylbenzotriazole and the oleoyl chain. The structure of MeBz-2-C18 was characterized by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Subsequently, the storage stability and tribological behavior of MeBz-2-C18 and the commercial benzotriazole oleamide salt (T406) were comparatively evaluated. The covalently-bonded MeBz-2-C18 exhibits superior thermal stability, along with boosted storage stability and tribological performance in the synthetic base oil. Specifically, 0.5 wt.% addition of MeBz-2-C18 and T406 can reduce the average wear scar diameter (ave. WSD) by 21.6% and 13.9%, respectively. To further explore the micro-mechanism, the electrostatic potential (ESP) and worn surfaces were analyzed with scanning electron microscope-energy dispersive spectrometer (SEM–EDS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. The results show that MeBz-2-C18 possesses stronger adsorption on the metal surface, and its amide bond preferentially breaks during friction. This reduces the interfacial shear force and promotes the film formation of iron oxides, thus resulting in superior tribological performance.

Acylation of glycerolipids in mycobacteria

We report on the existence of two phosphatidic acid biosynthetic pathways in mycobacteria, a classical one wherein the acylation of the sn-1 position of glycerol-3-phosphate (G3P) precedes that of sn-2 and another wherein acylations proceed in the reverse order. Two unique acyltransferases, PlsM and PlsB2, participate in both pathways and hold the key to the unusual positional distribution of acyl chains typifying mycobacterial glycerolipids wherein unsaturated substituents principally esterify position sn-1 and palmitoyl principally occupies position sn-2. While PlsM selectively transfers a palmitoyl chain to the sn-2 position of G3P and sn-1-lysophosphatidic acid (LPA), PlsB2 preferentially transfers a stearoyl or oleoyl chain to the sn-1 position of G3P and an oleyl chain to sn-2-LPA. PlsM is the first example of an sn-2 G3P acyltransferase outside the plant kingdom and PlsB2 the first example of a 2-acyl-G3P acyltransferase. Both enzymes are unique in their ability to catalyze acyl transfer to both G3P and LPA.

Effects of fatty acyl chains on the interfacial rheological behaviors of amino acid surfactants

Amino acid surfactants derived from vegetable oils have attracted significant interest in the scientific community due to their excellent biocompatibility and low environmental impact. Because of the wide variety of vegetable oils, derived N-acyl amino acid surfactants may feature various fatty acyl groups and therefore offer diverse properties. According to the composition of commonly used vegetable oils, three main characteristics of fatty acyl structures, namely fatty acyl chain length, the number of CC bonds, and hydroxyl substituent, were summarized in this paper and a series of N-fatty acyl glycinate surfactants were synthesized. The specific effects of these three structural factors on the surface tension and interfacial rheological properties were systematically studied. In doing so, we found that an increase of fatty acyl chain length enhanced the interfacial activity and intermolecular interactions of N-fatty acyl glycinate surfactants. Thus, glycinate surfactants with longer fatty acyls could generate more compact adsorption films with a higher dilational modulus. The cis CC bonds in oleoyl and linoleoyl chains were found to bend the long hydrophobic tails, which might affect the compact arrangement of surfactant molecules and increased the viscoelasticity of interfacial films. In addition, the hydroxyl group on ricinoleoyl was found to inhibit the close packing of the hydrophobic tails and reduced intermolecular interactions. As a result, more viscoelastic films were formed by sodium N-ricinoleoylglycinate. The obtained results gained insights into the relationships between fatty acyl structural characteristics and the interfacial arrangements of N-acyl amino acid surfactants, which present a theoretical foundation for surfactant design and further application.

Enzyme-Assisted Synthesis of High-Purity, Chain-Deuterated 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine.

1-Palmitoyl-d31-2-oleoyl-d32-sn-glycero-3-phosphocholine (POPC-d63) with the palmitoyl and oleoyl chains deuterium-labeled was produced in three steps from 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine, deuterated palmitic acid, and deuterated oleic anhydride. Esterification at the sn-2 position was achieved under standard chemical conditions, using DMAP to catalyze the reaction between the 2-lysolipid and oleic anhydride-d64. Complete regioselective sn-1 acyl substitution was achieved in two steps using operationally simple, enzyme-catalyzed regioselective hydrolysis and esterification to substitute the sn-1 chain for a perdeuterated analogue. This method provides chain-deuterated POPC with high chemical purity (>96%) and complete regiopurity, useful for a variety of experimental techniques. This chemoenzymatic semisynthetic approach is a general, modular method of producing highly pure, mixed-acyl phospholipids, where the advantages of both chemical synthesis (efficiency, high yields) and biocatalytic synthesis (specificity, nontoxicity) are realized.

Interfacial Water Structure at Zwitterionic Membrane/Water Interface: The Importance of Interactions between Water and Lipid Carbonyl Groups.

In this work, atomistic molecular dynamics (MD) simulations of palmitoyl-oleoyl-phosphatidylcholine (POPC) bilayer were carried out to investigate the effect of water models on membrane dipole potential, which is primarily associated with the preferential orientation of molecular dipoles at the membrane–water interface. We discovered that the overestimation of the dipole potential by the TIPS3P water model can be effectively reduced by the TIP4P water model. On the one hand, the TIP4P water model decreases the negative contribution of lipid to the dipole potential through influencing the orientation of lipid headgroups. On the other hand, the TIP4P water model reduces the positive contribution of water to the dipole potential by increasing the preference of H-down orientation (the water dipole orients toward the bilayer center). Interestingly, the TIP4P water model affects the orientation of interfacial water molecules more obviously than that of lipid headgroups, leading to the decrease in the dipole potential. Furthermore, the MD results revealed that the water close to the positively charged choline (namely, N-associated water) prefers the H-down orientation while the water around the negatively charged phosphate (namely, P-associated water) favors the H-up orientation, in support of recent experimental and MD studies. However, interfacial water molecules are more strongly influenced by the phosphate groups than by the choline groups, resulting in the net H-up orientation (the water dipole orients toward the bilayer center) in the region of lipid headgroups. In addition, it is intriguing that the preference of H-up orientation decreases when water molecules penetrate more deeply into the lipid bilayer. This is attributed to the counteracting effect of lipid carbonyl groups, and the effect varies with the lipid chains (oleoyl and palmitoyl chains), suggesting the important role of lipid carbonyl groups.

Behavior of Doxorubicin Lipophilic Conjugates in Liposomal Lipid Bilayers

Preparation of liposomal formulations containing water-soluble drugs in the form of lipophilic prodrugs in their lipid bilayer is of considerable interest. Previously, we synthesized doxorubicin dioleoyl glyceride and oleoyl conjugates intended for incorporation into fluid-phase liposomal bilayers. In this work, we studied the behavior of lipid conjugates in bilayers prepared from palmitoyl oleoyl phosphatidylcholine and dimyristoyl phosphatidylcholine using methods of fluorescence spectroscopy and molecular modeling. The conjugates were shown to have limited mobility in lipid bilayers, which can be explained by the formation of hydrogen bonds between the doxorubicin aglycone and the lipid phosphate groups. In the liposome membrane, lipophilic conjugates also tend to form clusters through interaction of doxorubicin moieties. Oleoyl chains stretch in parallel to the acyl residues of phospholipids. Due to the formation of a larger number of hydrogen bonds, the oleoyl conjugates interacted with the bilayer more effectively than the dioleoyl glyceride counterparts. These properties of doxorubicin conjugates can affect both the possibility of their incorporation into the lipid bilayer (from the therapeutic effect point of view) and intracellular release of the antibiotic drug by means of enzymolysis.

P-243 - Radical induced oxidation of di-oleoyl phosphatidylserine using mass spectrometry revealed preferential oxydation of Sn-2 oleoyl chain

Phosphatidylserine (PS) oxidation products (oxPS) play several roles in cell signaling, in immunity and in cell apoptosis. These different roles seem to be related to different oxPS species that can be generated in vivo. Yet, oxPS formed in biological systems are far from being totally characterized. In this study we evaluated the oxidation pattern of PS bearing two oleic acids (OOPS), one of the most abundant PS molecular species present in mammalian cells, using mass spectrometry (MS) approach. Oxidative modifications of OOPS was induced by hydroxyl radical generated under Fenton reaction. Oxidation products with hydroperoxide, hydroxy and keto groups were identified, similarly to what was previous reported for PS species with one oleic acid (OA). Multiple oxidation products, such as di-hydroperoxides were also observed, and revealed that both hydroperoxy moieties are preferentially linked to the oleoyl fatty acid in sn-2, revealing that radical mediate oxidation is not random. Also, this study shows for the first time that OA can suffer the insertion of multiple oxidative groups, providing further insight on possible oxPS formed in vivo.

Oleoyl-Chitosan-Based Nanofiber Mats Impregnated with Amniotic Membrane Derived Stem Cells for Accelerated Full-Thickness Excisional Wound Healing.

Wound healing management is a major challenge for critical full-thickness skin wounds. Development of nanofibrous scaffolds with tunable wettability, degradation, and biocompatibility are highly desirable. Herein, we demonstrated synthesis of oleoyl chitosan (OC) by grafting monounsaturated fatty acid residue, C18 oleoyl chain, to the backbone of chitosan molecule and blending with gelatin to form the nanofiber mats. The physicochemical properties of the nanofiber mats revealed mechanical strength, moderate surface wettability, and suitable degradation rate. The nanofibrous mats showed excellent in vitro cytocompatibility with human amniotic membrane-derived stem cells (HAMSCs) in terms of enhanced adhesion and proliferation owing to biomimetic nanoarchitecture and chemical cues. Furthermore, the fabricated nanofiber was implanted with and without preseeded HAMSCs in the full-thickness wound to evaluate the skin wound healing efficacy in a rat model. Histological and immunohistochemical studies were conducted to evaluate the plausible changes of tissue architecture and expression of molecular markers involved in wound healing process. Both acellular and HAMSCs incorporated cellular nanofibers promoted wound contraction remarkably with superior skin tissue regeneration in terms of enhanced collagen synthesis, re-epithelialization and initiation of epithelial cells stratification compared to control group.

Biophysical Changes of Lipid Membranes in the Presence of Ethanol at Varying Concentrations.

Ethanol is widely used as an additive to gasoline, and production of ethanol can come from single-celled organisms such as yeast. We systematically studied the influence of ethanol on common lipids found in yeast plasma membranes, specifically phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylcholine (PC). Molecular dynamics simulations were used to probe changes to the biophysical properties of membranes with varying equilibrated bulk ethanol concentrations less than 25 mol %. The palmitoyl oleoyl (PO, 18:1/16:0) chain was used for all lipids, and a mixed bilayer of POPE/POPS (7:3 ratio) was also simulated. Ethanol was found to interact strongly with POPC, and thus its surface area per lipid, chain order, and electron density profiles differ the most from the neat bilayer. At 12 mol % ethanol in the bulk, ethanol penetrated into the hydrophobic core for all membranes studied, but POPC had the highest penetration. Although the anionic headgroup of POPS acted as a protectant for membrane structure compared to the zwitterionic lipids, this was not the case for the POPE/POPS mixture that showed more penetration of ethanol into the membrane than the single-component membranes. To fully characterize the impact of ethanol on yeast plasma membranes, our results suggest that experiments and simulations need to consider representative mixtures of lipids that exist in vivo.

Structural and mechanical properties of cardiolipin lipid bilayers determined using neutron spin echo, small angle neutron and X-ray scattering, and molecular dynamics simulations.

The detailed structural and mechanical properties of a tetraoleoyl cardiolipin (TOCL) bilayer were determined using neutron spin echo (NSE) spectroscopy, small angle neutron and X-ray scattering (SANS and SAXS, respectively), and molecular dynamics (MD) simulations. We used MD simulations to develop a scattering density profile (SDP) model, which was then utilized to jointly refine SANS and SAXS data. In addition to commonly reported lipid bilayer structural parameters, component distributions were obtained, including the volume probability, electron density and neutron scattering length density. Of note, the distance between electron density maxima DHH (39.4 Å) and the hydrocarbon chain thickness 2DC (29.1 Å) of TOCL bilayers were both found to be larger than the corresponding values for dioleoyl phosphatidylcholine (DOPC) bilayers. Conversely, TOCL bilayers have a smaller overall bilayer thickness DB (36.7 Å), primarily due to their smaller headgroup volume per phosphate. SDP analysis yielded a lipid area of 129.8 Å(2), indicating that the cross-sectional area per oleoyl chain in TOCL bilayers (i.e., 32.5 Å(2)) is smaller than that for DOPC bilayers. Multiple sets of MD simulations were performed with the lipid area constrained at different values. The calculated surface tension versus lipid area resulted in a lateral area compressibility modulus KA of 342 mN m(-1), which is slightly larger compared to DOPC bilayers. Model free comparison to experimental scattering data revealed the best simulated TOCL bilayer from which detailed molecular interactions were determined. Specifically, Na(+) cations were found to interact most strongly with the glycerol hydroxyl linkage, followed by the phosphate and backbone carbonyl oxygens. Inter- and intra-lipid interactions were facilitated by hydrogen bonding between the glycerol hydroxyl and phosphate oxygen, but not with the backbone carbonyl. Finally, analysis of the intermediate scattering functions from NSE spectroscopy measurements of TOCL bilayers yielded a bending modulus KC of 1.06 × 10(-19) J, which was larger than that observed in DOPC bilayers. Our results show the physicochemical properties of cardiolin bilayers that may be important in explaining their functionality in the inner mitochondrial membrane.

The Curvature Induction of Surface-Bound Antimicrobial Peptides Piscidin 1 and Piscidin 3 Varies with Lipid Chain Length.

The initial steps of membrane disruption by antimicrobial peptides (AMPs) involve binding to bacterial membranes in a surface-bound (S) orientation. To evaluate the effects of lipid composition on the S state, molecular dynamics simulations of the AMPs piscidin 1 (p1) and piscidin 3 (p3) were carried out in four different bilayers: 3:1 DMPC/DMPG, 3:1 POPC/POPG, 1:1 POPE/POPG, and 4:1 POPC/cholesterol. In all cases, the addition of 1:40 piscidin caused thinning of the bilayer, though thinning was least for DMPC/DMPG. The peptides also insert most deeply into DMPC/DMPG, spanning the region from the bilayer midplane to the headgroups, and thereby only mildly disrupting the acyl chains. In contrast, the peptides insert less deeply in the palmitoyl-oleoyl containing membranes, do not reach the midplane, and substantially disrupt the chains, i.e., the neighboring acyl chains bend under the peptide, forming a basket-like conformation. Curvature free energy derivatives calculated from the simulation pressure profiles reveal that the peptides generate positive curvature in membranes with palmitoyl and oleoyl chains but negative curvature in those with myristoyl chains. Curvature inductions predicted with a continuum elastic model follow the same trends, though the effect is weaker, and a small negative curvature induction is obtained in POPC/POPG. These results do not directly speak to the relative stability of the inserted (I) states or ease of pore formation, which requires the free energy pathway between the S and I states. Nevertheless, they do highlight the importance of lipid composition and acyl chain packing.

The Orientation and Dynamics of Estradiol and Estradiol Oleate in Lipid Membranes and HDL Disc Models

Estradiol (E2) and E2 oleate associate with high-density lipoproteins (HDLs). Their orientation in HDLs is unknown. We studied the orientation of E2 and E2 oleate in membranes and reconstituted HDLs, finding that E2 and E2 oleate are membrane-associated and highly mobile. Our combination of NMR measurements, molecular dynamics simulation, and analytic theory identifies three major conformations where the long axis of E2 assumes a parallel, perpendicular, or antiparallel orientation relative to the membrane’s z-direction. The perpendicular orientation is preferred, and furthermore, in this orientation, E2 strongly favors a particular roll angle, facing the membrane with carbons 6, 7, 15, and 16, whereas carbons 1, 2, 11, and 12 point toward the aqueous phase. In contrast, the long axis of E2 oleate is almost exclusively oriented at an angle of ∼60° to the z-direction. In such an orientation, the oleoyl chain is firmly inserted into the membrane. Thus, both E2 and E2 oleate have a preference for interface localization in the membrane. These orientations were also found in HDL discs, suggesting that only lipid-E2 interactions determine the localization of the molecule. The structural mapping of E2 and E2 oleate may provide a design platform for specific E2-HDL-targeted pharmacological therapies.

Structure-delivery relationships of lysine-based gemini surfactants and their lipoplexes.

The synthesis and properties of gemini surfactants of the type (R(1)(CO)-Lys(H)-NH)2(CH2)n are reported. For a spacer length of n = 6, the hydrophobic acyl tail was varied in length (R(1) = C8, C10, C12, C14, C16, and C18) and, for R(1) = C18, the degree of unsaturation. For R(1)(CO) = oleoyl (C18:1 Z) the spacer length (n = 2-8) and the stereochemistry of the lysine building block were varied; a 'half-gemini' derivative with a single oleoyl tail and head group was also prepared. The potential of the gemini surfactants to transfer polynucleotides across a cell membrane was investigated by transfection of HeLa cells with beta-galactosidase, both in the presence and absence of the helper lipid DOPE. Oleoyl was found to be by far the best hydrophobic tail for this biological activity, whereas the effect of the lysine stereochemistry was less pronounced. The effect of an optimum spacer length (n = 6) was observed only in the absence of helper lipid. The most active surfactant, i.e. the one with oleoyl chains and n = 6, formed liposomes with sizes in the range of 60-350 nm, and its lipoplex underwent a transition from a lamellar to a hexagonal morphology upon lowering the pH from 7 to 3.

Design and Evaluation of a PEGylated Lipopeptide Equipped with Drug-Interactive Motifs as an Improved Drug Carrier

Micelles are attractive delivery systems for hydrophobic drugs due to their small size and the ease of application. However, the limited drug loading capacity and the intrinsic poor stability of drug-loaded formulations represent two major issues for some micellar systems. In this study, we designed and synthesized a micelle-forming PEG-lipopeptide conjugate with two Fmoc groups located at the interfacial region, and two oleoyl chains as the hydrophobic core. The significance of Fmoc groups as a broadly applicable drug-interactive motif that enhances the carrier-drug interaction was examined using eight model drugs of diverse structures. Compared with an analogue without carrying a Fmoc motif, PEG5000-(Fmoc-OA)₂ demonstrated a lower value of critical micelle concentration and three-fold increases of loading capacity for paclitaxel (PTX). These micelles showed tubular structures and small particle sizes (∼70 nm), which can be lyophilized and readily reconstituted with water without significant changes in particle sizes. Fluorescence quenching study illustrated the Fmoc/PTX π-π stacking contributes to the carrier/PTX interaction, and drug-release study demonstrated a much slower kinetics than Taxol, a clinically used PTX formulation. PTX/PEG5000-(Fmoc-OA)₂ mixed micelles exhibited higher levels of cytotoxicity than Taxol in several cancer cell lines and more potent inhibitory effects on tumor growth than Taxol in a syngeneic murine breast cancer model (4T1.2). We have further shown that seven other drugs can be effectively formulated in PEG5000-(Fmoc-OA)₂ micelles. Our study suggests that micelle-forming PEG-lipopeptide surfactants with interfacial Fmoc motifs may represent a promising formulation platform for a broad range of drugs with diverse structures.

Nanoassembly of Surfactants with Interfacial Drug-Interactive Motifs as Tailor-Designed Drug Carriers

PEGylated lipopeptide surfactants carrying drug-interactive motifs specific for a peptide-nitroxide antioxidant, JP4-039, were designed and constructed to facilitate the solubilization of this drug candidate as micelles and emulsion nanoparticles. A simple screening process based on the ability that prevents the formation of crystals of JP4-039 in aqueous solution was used to identify agents that have potential drug-interactive activities. Several protected lysine derivatives possessing this activity were identified, of which α-Fmoc-ε-t-Boc lysine is the most potent, followed by α-Cbz- and α-iso-butyloxycarbonyl-ε-t-Boc-lysine. Using a polymer-supported liquid-phase synthesis approach, a series of synthetic lipopeptide surfactants with PEG headgroup, varied numbers and geometries of α-Fmoc or α-Cbz-lysyl groups located at interfacial region as the drug-interactive domains, and oleoyl chains as the hydrophobic tails were synthesized. All α-Fmoc-lysyl-containing lipopeptide surfactants were able to solubilize JP4-039 as micelles, with enhanced solubilizing activity for surfactants with increased numbers of α-Fmoc groups. The PEGylated lipopeptide surfactants with α-Fmoc-lysyl groups alone tend to form filamentous or wormlike micelles. The presence of JP4-039 transformed α-Fmoc-containing filamentous micelles into dots and barlike mixed micelles with substantially reduced sizes. Fluorescence quenching and NMR studies revealed that the drug and surfactant molecules were in close proximity in the complex. JP4-039-loaded emulsion carrying α-Cbz-containing surfactants demonstrated enhanced stability over drug-loaded emulsion without lipopeptide surfactants. JP4-039 emulsion showed a significant mitigation effect on mice exposed to a lethal dose of radiation. PEGylated lipopeptides with an interfacially located drug-interactive domain are therefore tailor-designed formulation materials potentially useful for drug development.

Insight into the Properties of Cardiolipin Containing Bilayers from Molecular Dynamics Simulations, Using a Hybrid All-Atom/United-Atom Force Field.

Simulation of three models of cardiolipin (CL) containing membranes using a new set of parameters for tetramyristoyl and tetraoleoyl CLs has been developed in the framework of the united-atom CHARMM27-UA and the all-atom CHARMM36 force fields with the aim of performing molecular dynamics (MD) simulations of cardiolipin-containing mixed-lipid membranes. The new parameters use a hybrid representation of all-atom head groups in conjunction with implicit-hydrogen united-atom (UA) to describe the oleoyl and myristoyl chains of the CLs, in lieu of the fully atomistic description, thereby allowing longer simulations to be undertaken. The physicochemical properties of the bilayers were determined and compared with previously reported data. Furthermore, using tetramyristoyl CL mixed with POPG and POPE lipids, a mitochondrial membrane was simulated. The results presented here show the different behavior of the bilayers as a result of the lipid composition, where the length of the acyl chain and the conformation of the headgroup can be associated with the mitochondrial membrane properties. The new hybrid CL parameters prove to be well suited for the simulation of the molecular structure of CL-containing bilayers and can be extended to other lipid bilayers composed of CLs with different acyl chains or alternate head groups.

Compositional and structural studies of the oils from two edible seeds: Tiger nut, Cyperus esculentum, and asiato, Pachira insignis, from Ghana

A comprehensive lipid profiling has been carried out on the seed oils of tiger nut, Cyperus esculentum, and asiato, Pachira insignis, from Ghana in order to evaluate their potential uses for the region. Composition of FAs and phytosterols were determined using GC–MS, while tocol composition was determined with HPLC. TAG composition and regiochemistry were determined using ES-FTICR-MS and 13C NMR, respectively. The major FA components in asiato seed oil were palmitic acid (56.58%) and sterculic and dihydrosterculic acids (20.06% combined). The major FA components in tiger nut oil were oleic (65.55%), palmitic (16. 32%), and linoleic (12.13%) acids. Asiato seed oil had 18 major TAG classes, dominated by, C51:1 (38.45%) and C50:1 (13.941%). Tiger nut oil had 7 major TAG classes, with C54:3 (29.00%) and C52:2 (27.82%) dominating. The sn-1/3 and sn-2 positions in the TAGS for asiato oil were predominantly occupied by saturated acyl chains (87.25%) and cyclic acyl chains (71.44%), respectively. Oleoyl chain primarily occupied both sn-1/3 (52.68%) and sn-2 (77.62%) positions in the tiger nut oil. Total tocol content in asiato oil was 200.31μg/g, with γ-tocopherol (182.99μg/g) dominating. Tiger nut oil had a total tocol content of 120.10μg/g, dominated by α-tocopherol (86.73) and β-tocopherol (33.37μg/g).Tiger nut oil had total 4-desmethylsterol content of 986μg/g, dominated by β-sitosterol (517.25μg/g) and stigmasterol (225.25μg/g), while asiato oil had total desmethylsterol content of 590.24μg/g, dominated by β-sitosterol (518.91μg/g). The presence of cyclopropenoid FAs in asiato oil makes it unsuitable for food uses. Tiger nut oil can replace imported olive oil in food products in the West African region.

Aerobic fate and impact of canola oil in aquatic media

The fate of canola oil in water under aerobic conditions was studied in respirometry tests. First-order biodegradation rates were estimated for a refined oil (commercial canola oil, CCO), 0.0037 h−1, and for two synthetic oils, one prepared with mono-acid triacylglycerols (TAO) 0.0048 h−1, and the other with free fatty acids and glycerol (FAO) 0.0038 h−1. Two abiotic factors limited substrate bioavailability: the autoxidation of the oleoyl chains and the insolubility of fully saturated triacylglycerols. In addition, the ecotoxic impact of the oils was assessed by Microtox® toxicity. For the acylglycerol oils, luminescent bacteria inhibition was not detected in the water phase, whereas solid-phase EC50 values below 1.8% sample volume were measured. Toxicity was observed in the aqueous phase (EC50 < 16%) during the biodegradation of FAO. In this case, however, solid-phase toxicity was extremely high at the beginning of the test (0.02%) but the toxicity dissipated 480 h into the experiment.

Compositional and Structural Studies of the Major and Minor Components in Three Cameroonian Seed Oils by GC–MS, ESI‐FTICR‐MS and HPLC

AbstractThe lipid components of three Cameroonian seed oils, ke tchock (Aframomum arundinaceum), njangsa (Ricinodendron heudelotii) and calabash nutmeg (Monodora myristica), have been investigated. Gas chromatography (GC)–mass spectrometry (MS) fatty acid (FA) analysis showed M. myristica seed oil to be dominated by linoleic (49.29%) and oleic (37.17%) acids; R. heudelotii was mainly linoleic (58.73%), followed by stearic (15.00%) and oleic (14.21%) acids; A. arundinaceum was predominantly oleic (65.76%) and palmitic (20.36%) acids. Electrospray ionization (ESI)‐Fourier transform ion cyclotron resonance (FTICR)‐MS analysis showed seven major triacylglycerol (TAG) classes for M. myristica, with C54:5, C54:4 and C54:6 dominating. R. heudelotii had eight major TAG classes with C54:8, C54:7 and C54:6 being most abundant. A. arundinaceum also had eight major TAG classes with C52:2, C54:3 and C50:2 dominating. 13C nuclear magnetic resonance (NMR) analysis of the TAGs showed that both sn‐1,3 and sn‐2 positions were predominantly occupied by linoleoyl and oleoyl chains. High‐performance liquid chromatography (HPLC) fluorescence detector (FLD) analysis showed that M. myristica contained only α‐ and β‐tocopherols (195.40 and 73.95 µg/g, respectively), R. heudelotii contained mainly γ‐tocopherol (289.40 µg/g), and A. arundinaceum had mainly γ‐ and β‐tocopherols (236.78 and 124.93 µg/g, respectively). GC–MS analysis of the unsaponifiable matter showed that β‐sitosterol was the most abundant phytosterol in all three seed oils. The absolute amounts of 4‐desmethylsterols were 196.15, 608.71 and 362.15 µg/g for M. myristica, R. heudelotii and A. arundinaceum seed oils, respectively. These compositional and structural studies provide justification for the use of all three seed oils in food products.

Bis (monoacylglycero) phosphate interfacial properties and lipolysis by pancreatic lipase-related protein 2, an enzyme present in THP-1 human monocytes

The interfacial physical properties of bis(monoacylglycero)phosphate (BMP) and its derivatives with three oleoyl chains (hemi-BDP) and four oleoyl chains (bis(diacylglycero)phosphate, BDP) were investigated using Langmuir monomolecular films. The mean molecular area of BMP at the collapse surface pressure (45mN m−1) was similar to those measured with other phospholipids bearing two acyl chains (66 and 59.6Å2 molecule−1 at pH 5.5 and 8.0, respectively). In Hemi-BDP and BDP, the mean molecular area increased by 26 and 35Å2 molecule−1 per additional acyl chain at pH 5.5 and 8.0, respectively. When BMP was added to a phospholipid mixture mimicking late endosome membrane composition at pH 8.0, the mean phospholipid molecular area increased by 7% regardless of the surface pressure. In contrast, the variation in molecular area was surface pressure-dependent at pH 5.5, a pH value close to that of intra-endosomal content. BMP and hemi-BDP, but not BDP, were hydrolyzed by pancreatic lipase-related protein 2 (PLRP2), which exhibits phospholipase A1 activity. At pH 5.5, the maximum activities of PLRP2 on BMP were recorded at high surface pressures (25–35mN/m). At pH 8.0, the PLRP2 activity vs. surface pressure showed a bell-shaped curve with maximum activities at 15mN/m for both BMP and hemi-BDP. This is a new activity for this enzyme which could degrade cellular BMP since both human PLRP2 (HPLRP2) and BMP were localized in human monocytic THP-1 cells. This is the first report on the cellular localization of HPLRP2 in human monocytes.