Synthesis, physicochemical properties, and health aspects of structured lipids: A review.

Structured lipids (SLs) refer to a new type of functional lipids obtained by chemically, enzymatically, or genetically modifying the composition and/or distribution of fatty acids in the glycerol backbone. Due to the unique physicochemical characteristics and health benefits of SLs (for example, calorie reduction, immune function improvement, and reduction in serum triacylglycerols), there is increasing interest in the research and application of novel SLs in the food industry. The chemical structures and molecular architectures of SLs define mainly their physicochemical properties and nutritional values, which are also affected by the processing conditions. In this regard, this holistic review provides coverage of the latest developments and applications of SLs in terms of synthesis strategies, physicochemical properties, health aspects, and potential food applications. Enzymatic synthesis of SLs particularly with immobilized lipases is presented with a short introduction to the genetic engineering approach. Some physical features such as solid fat content, crystallization and melting behavior, rheology and interfacial properties, as well as oxidative stability are discussed as influenced by chemical structures and processing conditions. Health-related considerations of SLs including their metabolic characteristics, biopolymer-based lipid digestion modulation, and oleogelation of liquid oils are also explored. Finally, potential food applications of SLs are shortly introduced. Major challenges and future trends in the industrial production of SLs, physicochemical properties, and digestion behavior of SLs in complex food systems, as well as further exploration of SL-based oleogels and their food application are also discussed.

Synthesis of two new lipid mediators from docosahexaenoic acid by combinatorial catalysis involving enzymatic and chemical reaction.

Omega-3 polyunsaturated fatty acids (PUFAs) have been known to have beneficial effects in the prevention of various diseases. Recently, it was identified that the bioactivities of omega-3 are related to lipid mediators, called pro-resolving lipid mediators (SPMs), converted from PUFAs, so they have attracted much attention as potential pharmaceutical targets. Here, we aimed to build an efficient production system composed of enzymatic and chemical catalysis that converts docosahexaenoic acid (DHA) into lipid mediators. The cyanobacterial lipoxygenase, named Osc-LOX, was identified and characterized, and the binding poses of enzyme and substrates were predicted by ligand docking simulation. DHA was converted into three lipid mediators, a 17S-hydroxy-DHA, a 7S,17S-dihydroxy-DHA (RvD5), and a 7S,15R-dihydroxy-16S,17S-epoxy-DPA (new type), by an enzymatic reaction and deoxygenation. Also, two lipid mediators, 7S,15R,16S,17S-tetrahydroxy-DPA (new type) and 7S,16R,17S-trihydroxy-DHA (RvD2), were generated from 7S,15R-dihydroxy-16S,17S-epoxy-DPA by a chemical reaction. Our study suggests that discovering new enzymes that have not been functionally characterized would be a powerful strategy for producing various lipid mediators. Also, this combination catalysis approach including biological and chemical reactions could be an effective production system for the manufacturing lipid mediators.

Efficient production of bioactive structured lipids by fast acidolysis catalyzed by Yarrowia lipolytica lipase, free and immobilized in chitosan-alginate beads, in solvent-free medium.

Structured lipids (SL) represent a new generation of lipids, considered bioactive compounds. Medium-chain, oleic (18:1n-9), and medium-chain fatty acid (MCFA) structured lipids (MOM-SL) were produced by acidolysis reaction in solvent-free medium with capric (10:0) and lauric (12:0) free fatty acids (FFAs) and triolein or olive oil, using Yarrowia lipolytica lipase as biocatalyst. MCFAs were rapidly incorporated into sn-1,3 SL in acidolysis reactions with triolein and olive oil, up until 30% of incorporation efficiency of capric and lauric acids in SLs. The kinetics of MCFA incorporation in MOM-SL was influenced by the FFA:TAG molar ratio, and for reactions between triolein and lauric acid, increasing FFA:TAG from 2:1 to 4:1 enhanced MCFA incorporation in SL. Y. lipolytica lipase showed a strictly 1,3-regioselective profile in acidolysis reaction, confirmed by nuclear magnetic resonance spectroscopy. Immobilization of this lipase by microencapsulation in chitosan-alginate beads resulted in similar incorporation efficiency for lauric acid with olive oil TAG and this reaction could be performed for 5 cycles without catalytic activity loss. This lipase showed promising properties as a potential biocatalyst that may be effectively used in production of bioactive structured lipids, which might be applied for prevention of metabolic and inflammatory disorders related to obesity.

Synthesis and Characterization of Valacyclovir HCl Hybrid Solid Lipid Nanoparticles by Using Natural Oils.

BACKGROUND: The Jojoba Simmondsia Chinensis oil is used as one of the main ingredients which has an antioxidant, moisturizing and stabilizing activity. Likewise, grape seed (Vitis vinifera) oil is also used in this preparation which also has some remarkable medicinal properties such as antioxidant, astringent and is also used as a moisturizer. The Valacyclovir Solid Lipid Nanoparticles (SLN) are prepared in combination. OBJECTIVE: The prime objective of the study was to prepare a nanodispersion with good stability indicating zeta potential. The formulations were prepared by varying concentrations of jojoba oil and grape seed oil which form the hybrid nanoparticles with the drug. METHODS: The high-pressure hot-homogenization technique was used to prepare the nanoparticles. The prepared nanoparticles were subjected to characterization analysis such as Mean particle size, Zaverage, and Zeta potential by using Dynamic Light Scattering (DLS) and Photon Correlation Spectroscopy (PCS). The best formulation was subjected to Transmission Electron Microscopy (TEM) technique for surface morphology and other characterizations. The crystalline pattern of the drug alone, drug-loaded nanoparticles and nanoparticles without the drug was studied by XRD. The drug excipients compatibility studies were performed by using Fourier-Transform Infrared Spectroscopy (FTIR) Differential Scanning Calorimetry and (DSC). The other factors such as in vitro drug release, and % drug entrapment efficiency were studied by using suitable methods. RESULTS: The results demonstrated that the particles are in nano range with good stability with appreciable Zeta potential (-48.2±mV). The selected formulations were analyzed for MPS which demonstrated the value of 306.7±183.4 and 416.5±289.3. The best formulation VNP5 demonstrated the Bellshaped curve and confirmed the uniform distribution. CONCLUSION: Based on the patents, it was demonstrated that valacyclovir is widely used in the treatment and prophylaxis of viral infections in human, particularly infections caused by the herpes group of viruses. Valacyclovir is an effective drug for the treatment of cold sores.

Evaluation of the drug loading capacity of different lipid nanoparticle dispersions by passive drug loading.

When using lipid nanoparticles as drug carrier system it is important to know how much drug can be loaded to the nanoparticles. The mainly used drug loading procedure is an empirical approach dissolving the drug in the liquid lipid during preparation of the nanoparticles. This approach does not necessarily lead to the truly loadable amount, as the lipid can, e.g. be overloaded, in particular when it is processed in the heat. In this work, a different procedure, passive drug loading, was evaluated to determine the drug loading capacity of various lipid nanoparticles (supercooled trimyristin emulsion droplets, solid trimyristin nanoparticles, tristearin nanoparticles in the α-modification and cholesteryl myristate nanoparticles in the supercooled smectic as well as in the crystalline state). The nanoparticle dispersions were exposed to eight different model drug compounds (betamethasone-17-valerate, carbamazepine, diazepam, flufenamic acid, griseofulvin, ibuprofen, retinyl palmitate, ubidecarenone) in the bulk state, which varied in partition coefficient and aqueous solubility, and equilibrated over time. The passive loading procedure had no relevant impact on the particle sizes or the physicochemical state of the nanoparticles. The loadable drug amount differed distinctly for the different model compounds and also between the different types of lipid nanoparticles. For most compounds, the loaded amount was much higher than the aqueous solubility. Trimyristin-based dispersions generally had the highest loading capacity, the emulsion usually being equal or superior to the solid trimyristin nanoparticles. For betamethasone-17-valerate, however, solid lipid nanoparticles exhibited by far the highest drug load. The extremely lipophilic model drugs retinyl palmitate and ubidecarenone could not be loaded with the passive approach.

Efficient delivery of genome-editing proteins using bioreducible lipid nanoparticles.

A central challenge to the development of protein-based therapeutics is the inefficiency of delivery of protein cargo across the mammalian cell membrane, including escape from endosomes. Here we report that combining bioreducible lipid nanoparticles with negatively supercharged Cre recombinase or anionic Cas9:single-guide (sg)RNA complexes drives the electrostatic assembly of nanoparticles that mediate potent protein delivery and genome editing. These bioreducible lipids efficiently deliver protein cargo into cells, facilitate the escape of protein from endosomes in response to the reductive intracellular environment, and direct protein to its intracellular target sites. The delivery of supercharged Cre protein and Cas9:sgRNA complexed with bioreducible lipids into cultured human cells enables gene recombination and genome editing with efficiencies greater than 70%. In addition, we demonstrate that these lipids are effective for functional protein delivery into mouse brain for gene recombination in vivo. Therefore, the integration of this bioreducible lipid platform with protein engineering has the potential to advance the therapeutic relevance of protein-based genome editing.

Formulation and In Vitro and In Vivo Evaluation of Lipid-Based Terbutaline Sulphate Bi-layer Tablets for Once-Daily Administration.

The objective of this study was to prepare and evaluate terbutaline sulphate (TBS) bi-layer tablets for once-daily administration. The bi-layer tablets consisted of an immediate-release layer and a sustained-release layer containing 5 and 10 mg TBS, respectively. The sustained-release layer was developed by using Compritol®888 ATO, Precirol® ATO 5, stearic acid, and tristearin, separately, as slowly eroding lipid matrices. A full 4 × 2(2) factorial design was employed for optimization of the sustained-release layer and to explore the effect of lipid type (X 1), drug-lipid ratio (X 2), and filler type (X 3) on the percentage drug released at 8, 12, and 24 h (Y 1, Y 2, and Y 3) as dependent variables. Sixteen TBS sustained-release matrices (F1-F16) were prepared by melt solid dispersion method. None of the prepared matrices achieved the targeted release profile. However, F2 that showed a relatively promising drug release was subjected to trial and error optimization for the filler composition to develop two optimized matrices (F17 and F18). F18 which consisted of drug-Compritol®888 ATO at ratio (1:6 w/w) and Avicel PH 101/dibasic calcium phosphate mixture of 2:1 (w/w) was selected as sustained-release layer. TBS bi-layer tablets were evaluated for their physical properties, in vitro drug release, effect of storage on drug content, and in vivo performance in rabbits. The bi-layer tablets showed acceptable physical properties and release characteristics. In vivo absorption in rabbits revealed initial high TBS plasma levels followed by sustained levels over 24 h compared to immediate-release tablets.

Castor oil as secondary carbon source for production of sophorolipids using Starmerella bombicola NRRL Y-17069.

Sophorolipids (SLs), a prominent member of the biosurfactants family are produced in acidic and/or lactonic form by yeast Starmerella bombicola NRRL Y-17069 when grown on hydrophilic or hydrophobic or both carbon sources. In current study, ricinoleic acid rich castor oil (10%) was used as hydrophobic and glycerol (10%) was used as hydrophilic carbon source. The yields of 24.5 ± 0.25 g/l sophorolipids were analyzed by anthrone and HPLC method which further increased upto 40.24 ± 0.76 g/l sophorolipids using fed batch process at 5L fermenter level. The structures of sophorolipids synthesized on castor oil were elucidated by liquid chromatography-mass spectrometer (LC-MS), (13)C and (1)H NMR. The results indicated that the ricinoleic acid (RA) gets hydroxylated at ω-1 position but incorporated into sophorolipids through already available hydroxyl group at 12(th) position. It resulted in the production of a novel sophorolipids with hydroxyl fatty acid as side chain and has applications as surfactant for novel drug delivery, anti microbial agent, cosmetic ingredient and emulsifier.

Preparation, optimization and characteristic of huperzine a loaded nanostructured lipid carriers.

The objective of the present work was to study the preparation, optimization and characteristics of Huperzine A (Hup A), an effective Traditional Chinese Medicine treatment of Alzheimer's disease (AD), loaded nanostructured lipid carriers (NLC). NLC were successfully prepared by a modified method of melt ultrasonication followed by high pressure homogenization using Cetyl Palmitate (CP) as the solid lipid, Miglyol((R))812 as the liquid lipid, Soybean phosphatidylcholine (Spc) and Solutol HS15 as the emulsifiers. The best formulation was optimized with a three-factor, three-level Box-Behnken design. Independent variables studied were the amount of the mixed lipid, the amount of the emulsifier mixture and lipid/drug ratio in the formulation. The dependent variables were the particle size, entrapment efficiency (EE) and drug loading (DL). Properties of NLC such as the morphology, particle size, zeta potential, EE, DL and drug release behavior were investigated, respectively. As a result, the designed nanoparticles showed nearly spherical particles with a mean particle size of 120 nm and -22.93 + or - 0.91 mV. The EE (%) and DL (%) could reach up to 89.18 + or - 0.28% and 1.46 + or - 0.05%, respectively. Differential scanning calorimetry (DSC) of Hup A loaded NLC indicated no tendency of recrystallisation. In vitro release studies showed a burst release at the initial stage and followed by a prolonged release of Hup A from NLC up to 96 h. The results suggest that the presented Hup A loaded NLC system is a potential delivery system for improving drug loading capacity and controlled drug release.

Preparation and characterization of nanostructured lipid carriers loaded traditional Chinese medicine, zedoary turmeric oil.

BACKGROUND: The objective of this work was to study the preparation and characteristics of zedoary turmeric oil (ZTO), a traditional Chinese oily medicine, loaded with nanostructured lipid carriers (NLCs). METHOD: Aqueous dispersions of NLC were successfully prepared by melt-emulsification technique using Crodamol SS as the solid lipid, Miglyol 812N as the liquid oil, and soybean phosphatidylcholine (SbPC) as the emulsifier. Properties of NLC such as the particle size and its distribution, the transmission electron microscope (TEM), drug entrapment efficiency (EE), and drug release behavior were investigated, respectively. The Germacrone blood concentration after intravenous administration of ZTO-NLC was determined and compared with that of ZTO-injection. RESULT: As a result, the drug EEs were improved by adding the liquid lipid into the solid lipid of nanoparticles (SLNs). In vitro drug release experiments indicated that the prepared NLC could enhance the drug release rate over the SLN, and the drug release rate could be adjusted by the liquid lipid content in lipid nanospheres. X-ray and differential scanning calorimetry (DSC) measurements revealed that imperfect crystallization occurred in the inner core of the NLC particles. CONCLUSION: The results suggest that the presented NLC system might be a promising intravenous dosage form of water-insoluble oily drugs.

Preparation of solid lipid nanoparticles from W/O/W emulsions: preliminary studies on insulin encapsulation.

A method to produce solid lipid nanoparticles (SLN) from W/O/W multiple emulsions was developed applying the solvent-in-water emulsion-diffusion technique. Insulin was chosen as hydrophilic peptide drug to be dissolved in the acidic inner aqueous phase of multiple emulsions and to be consequently carried in SLN. Several partially water-miscible solvents with low toxicity were screened in order to optimize emulsions and SLN composition, after assessing that insulin did not undergo any chemical modification in the presence of the different solvents and under the production process conditions. SLN of spherical shape and with mean diameters in the 600-1200 nm range were obtained by simple water dilution of the W/O/W emulsion. Best results, in terms of SLN mean diameter and encapsulation efficiencies, were obtained using glyceryl monostearate as lipid matrix, butyl lactate as a solvent, and soy lecithin and Pluronic F68 as surfactants. Encapsulation efficiencies up to 40% of the loaded amount were obtained, owing to the actual multiplicity of the system; the use of multiple emulsion-derived SLN can be considered a useful strategy to encapsulate a hydrophilic drug in a lipid matrix.

Evaluation of spray congealing as technique for the preparation of highly loaded solid lipid microparticles containing the sunscreen agent, avobenzone.

Solid lipid microparticles (SLMs) loaded with high amounts of the sunscreen agent, butyl methoxydibenzoylmethane (avobenzone) were prepared in order to reduce its photoinstability. The microparticles were produced, using carnauba wax as lipidic material and phosphatidylcholine as the surfactant, by the classical melt dispersion method or the spray congealing technique with pneumatic atomizer. The sunscreen agent loading was 40.1-48.5% (w/w), with no significant differences between the production methods. However, release studies indicated that spray congealing enabled a more efficient modulation of avobenzone release from the SLMs (26% of encapsulated avobenzone released after 2 h as compared to 60% for melt dispersion). The photoprotective efficacy of the SLMs was evaluated after their introduction in a model cream. A statistically significant decrease of the light-induced degradation of avobenzone was obtained by the SLMs prepared by the melt dispersion procedure (the extent of degradation was 38.6 +/- 3.6% for nonencapsulated avobenzone and 32.1 +/- 4.3% for the microparticle-entrapped sunscreen). On the other hand, the SLMs produced by spray congealing achieved a more marked reduction in avobenzone photodecomposition to 15.4 +/- 4.1%. Therefore, the spray congealing technique was superior to the classical melt dispersion method for rapid and solvent free production of SLMs with a high avobenzone loading capacity.

Síntese de lipídios estruturados por interesterificação de banha e óleo de soja para obtenção de sucedâneo da gordura do leite humano / Synthesis of structure lipids by interesterification of lard and soybean oil for obtain human milk fat substitute

O leite humano é um alimento completo, possui todos os nutrientes em quantidade e qualidade necessárias, proporciona proteção contra infecções e alergias e estimula o sistema imunológico. Os lipídios do leite humano são fonte energética; veículos para as vitaminas lipossolúveis; contêm ácidos graxos poliinsaturados necessários para o desenvolvimento cerebral; contêm precursores de prostaglandinas e hormônios; e são constituintes essenciais para as membranas celulares. Muitas mães, por razões médicas, metabólicas ou econômicas, dependem de fórmulas artificiais para alimentar seus filhos. Portanto, a composição dos ácidos graxos e a sua distribuição nas cadeias dos triacilgliceróis devem ser alvos de estudos em fórmulas infantis, sendo que os triacilgliceróis do leite humano devem servir de modelo para os componentes lipídicos. Recentemente, diversos estudos apontam a interesterificação como alternativa para a produção de sucedâneos da gordura do leite humano. Assim, o objetivo deste trabalho foi explorar diversas possibilidades da modificação lipídica para a obtenção deste sucedâneo. As matérias-primas utilizadas foram banha e óleo de soja, gorduras facilmente obtidas e de baixo custo no Brasil. Neste trabalho, foram produzidos lipídios estruturados por interesterificação química e enzimática, sendo que na interesterificação enzimática foram utilizadas duas lipases puras, a AY30TM (Candida cylindracea) e a M10TM (Mucor circinelloides), e a lipase imobilizada Lipozyme TL IM (Thermomices lanuginosa). Os lipídios estruturados foram submetidos a análises de suas propriedades químicas e físicas, que foram comparadas às propriedades da gordura do leite humano e do lipídio estruturado comercial BetapolTM. Os resultados apresentados demonstraram a viabilidade da interesterificação como método de modificação para obtenção de lipídios estruturados sucedâneos da gordura do leite humano. Tendo em vista a possibilidade de maior controle reacional devido à especificidade das lipases e a busca por processos ambientalmente corretos, a interesterificação enzimática mostra-se alternativa mais interessante para esta modificação lipídica. A mistura de banha e óleo de soja demonstrou ser opção viável para a produção de sucedâneos da gordura do leite humano

Human milk is a complete food with all the nutrients in quantity and quality provides protection against infections and allergies and stimulates the immune system. The lipids of human milk are source of energy; vehicles for liposoluble vitamins; contain polyunsaturated fatty acids for brain development; contain precursors of prostaglandins, hormones; and are essential constituents to the cell membranes. Many mothers, for medical, metabolic or economic reasons, depend on artificial formulas to feed their children. Therefore, the composition of fatty acids and their distribution chains in the triacylglycerols must be targets of studies on infant formula, and the human milk triacylglycerols should be a model for the lipid components. Recently, several studies indicate the interesterification like an alternative for the production of substitutes of human milk fat. The objective of this study was to explore various possibilities of lipid modification to achieve this substitute. The raw materials used were lard and soybean oil, fats easily obtained and cheap in Brazil. In this work, were produced structured lipids by chemical and enzymatic interesterification. For enzymatic interesterification were used two pure lipases, AY30 TM (Candida cylindracea) and M10 (M (Mucor circinelloides) and one immobilized lipase, Lipozyme TL IM (Thermomices lanuginosa). The structured lipids were submitted to analysis of their chemical and physical properties, which were compared with the human milk fat and the structured commercial lipid Betapol TM. The results demonstrated the feasibility of interesterification as a method of modification to obtain structured lipids substitutes of human milk fat. The possibility of greater control reaction because the specificity of lipases and the search for environmentally correct procedures makes enzymatic interesterification the most attractive alternative for modifying lipids. The mixture of soybean oil and lard is a viable alternative for the production of human milk fat substitutes

Lipase-catalyzed transesterification of dihydrocaffeic acid with flaxseed oil for the synthesis of phenolic lipids.

Lipase-catalyzed transesterification reaction of dihydrocaffeic acid (DHCA) with flaxseed oil in organic solvent media was investigated. Using equal molar concentration of DHCA and flaxseed oil, only phenolic monoacylglycerols were obtained with a transesterification yield (TY) of 18.9%. A 1:4 DHCA to flaxseed oil ratio resulted in the production of both phenolic mono and diacylglycerols, with TY of 39.6 and 27.8%, respectively. On the other hand, when 1:8 ratio of DHCA to flaxseed oil was used, the TY of phenolic diacylglycerols (46.0%) was higher than that of the phenolic monoacylglycerols (33.3%). The TY of phenolic diacylglycerols increased from 25.1 to 55.8%, when the ratio of the hexane/2-butanone reaction medium was changed from 65:35 to 85:25 (v/v); however, the TY of phenolic monoacylglycerols decreased slightly from 34.0 to 31.8%. The relative proportion of the C(18:3)n-3 was higher in the phenolic mono and diacylglycerols, 64.9 and 59.5%, respectively, as compared to the original flaxseed oil, 53.1%. The radical scavenging ability of phenolic lipids was significant; however, it was about half than that of alpha-tocopherol.

Etoposide-loaded nanoparticles made from glyceride lipids: formulation, characterization, in vitro drug release, and stability evaluation.

The aim of the study was to prepare etoposide-loaded nanoparticles with glyceride lipids and then characterize and evaluate the in vitro steric stability and drug release characteristics and stability. The nanoparticles were prepared by melt emulsification and homogenization followed by spray drying of nanodispersion. Spray drying created powder nanoparticles with excellent redispersibility and a minimal increase in particle size (20-40 nm). Experimental variables, such as homogenization pressure, number of homogenization cycles, and surfactant concentration, showed a profound influence on the particle size and distribution. Spray drying of Poloxamer 407-stabilized nanodispersion lead to the formation of matrix-like structures surrounding the nanoparticles, resulting in particle growth. The in vitro steric stability test revealed that the lipid nanoparticles stabilized by sodium tauroglycocholate exhibit excellent steric stability compared with Poloxamer 407. All 3 glyceride nanoparticle formulations exhibited sustained release characteristics, and the release pattern followed the Higuchi equation. The spray-dried lipid nanoparticles stored in black polypropylene containers exhibited excellent long-term stability at 25 degrees C and room light conditions. Such stable lipid nanoparticles with in vitro steric stability can be a beneficial delivery system for intravenous administration as long circulating carriers for controlled and targeted drug delivery.

A synthesis of the phenolic lipid, 3-[(Z)-pentadec-8-enyl] catechol, (15:1)-urushiol.

A synthesis of (15:1)-urushiol, urushiol monoene, 3-[(Z)-pentadec-8-enyl] catechol, 1,2-dihydroxy-3-[(Z)-pentadec-8-enyl] benzene, one of the toxic principles of Rhus toxicodendron and of Rhus vernicifera is described. 6-Chlorohexan-1-ol protected at the OH group with ethyl vinyl ether reacted with 2,3-dimethoxybenzaldehyde in the presence of lithium to give, after removal of the protective group with methanolic 4-toluenesulphonic acid, 1-(2,3-dimethoxyphenyl) heptane-1,7-diol. Catalytic hydrogenolysis in ethanol with palladium-carbon selectively afforded 7-(2,3-dimethoxyphenyl)heptane-1-ol accompanied by a small proportion of the 7-(3-methoxyphenyl)heptane-1-diol, formed by demethoxylation. Reaction of the dimethoxy compound with boron tribromide resulted in both bromination and demethylation to give 7-(2,3-dihydroxyphenyl) heptylbromide. This bromide in tetrahydrofuran (THF) containing hexamethylphosphoric triamide reacted with excess lithium oct-1-yne to give 3-(pentadec-8-enyl)catechol which, by catalytic hydrogenation in ethyl acetate containing quinoline, selectively formed the required cis product, 3-[(Z)-pentadec-8-enyl]catechol which was identical chromatographically and spectroscopically with urushiol monoene separated from the natural product.

Selective adhesion, lipid exchange and membrane-fusion processes between vesicles of various sizes bearing complementary molecular recognition groups.

Equimolar mixtures of large unilamellar vesicles (LUVs) obtained from mixtures of egg lecithin and lipids containing complementary hydrogen bonding head groups (barbituric acid (BAR) and 2,4,6-triaminopyrimidine (TAP)) were shown to aggregate and fuse. These events have been studied in detail using electron microscopy and dynamic light scattering, and by fluorimetry using membrane or water-soluble fluorescence probes. It was shown that aggregation was followed by two competitive processes: a) lipid mixing leading to redispersion of the vesicles; b) fusion events generating much larger vesicles. In order to better understand the nature of the interaction, the effects of ionic strength and surface concentration of recognition lipids on the aggregation process were investigated by dynamic light scattering. Additionally, it was possible to inhibit the aggregation kinetics through addition of a soluble barbituric acid competitor. The study was extended to giant unilamellar vesicles (GUVs) to investigate the size effect and visualise the phenomena in situ. The interactions between complementary LUVs and GUVs or GUVs and GUVs were studied by optical microscopy using dual fluorescent labelling of both vesicle populations. A selective adhesion of LUVs onto GUVs was observed by electron and optical microscopies, whereas no aggregation took place in case of a GUV/GUV mixture. Furthermore, a fusion assay of GUV and LUV using the difference of size between GUV and LUV and calceine self-quenching showed that no mixing between the aqueous pools occured.

Synthesis of structured lipids and etherlipids with antioxidants: combination of a selena fatty acid and a selena fatty alcohol with a carotenoic acid in glyceride molecules.

Selenium and carotenoids show similar and complementary properties and protect against a variety of pathological processes. Mixtures of both compounds are found in nutritional supplements and are used to prevent several diseases. The synthetic connection of carotenoids with selenium in glycerols may increase the chemopreventive activity of the individual compounds. Beta-apo-8'-carotenoic acid and 7-selenacapryloic acid were esterified with glycerol to highly unsaturated stable di- and triglycerides. Intramolecular selenium:carotenoid ratios of 1:1, 2:1 and 1:2 were obtained for 1-(7-selenaoctanoyl)-3-(3beta-apo-8 -carotenoyl)-glycerol, 1,3-di-(beta-apo-8'-carotenoyl)-2-(7-selenaoctanoyl)-glycero l and 1,2-di-(7-selenaoctanoyl)-3-(beta-apo-8'-carotenoyl)-glycero l, respectively. The carotenoic acid was likewise connected to the pharmacologically interesting 11-selenalaurylglycerolether forming an alkyl-acylglyceride: 1-(11-selenadodecyl)-3-(beta-apo-8'-carotenoyl)-glycerol.