Different Degrees Of Unsaturation Research Articles

POLYMERS FROM BIOLOGICAL OILS

Vegetable oils, fish oil and oils from algae are excellent raw materials for new polymers. These oils differ in the structure and unsaturation, but each offer specific advantages. Vegetable oils are inexpensive and offer different degrees of unsaturation. Fish oils may have a very high degree of unsaturation. Algal oils are new raw materials with still unexplored possibilities. Most oils are triglycerides but cashew nut oil is an aromatic compound with a long hydrocarbon chain. Direct polymerization of oils has been used in coatings for a long time. Oils can be thermally polymerized by heating at a high temperature. The products are oligomers of high viscosity. We have developed a method for cationic polymerization of oils at mild conditions, useful as lubricants and modifiers for rubber, asphalt etc. However, for high strength materials, it is necessary to introduce functional groups such are hydroxyls, carboxyls, amine etc. Hydroxyls are the most useful ones, since they open the whole area of polyurethanes (foams, coatings, adhesives, elastomers and sealants). One can utilize the triglyceride structure or to use fatty acid derivatives, opening a wide field of combinations to suit different material requirements. This presentation will give a cross-section of different possibilities for creation of new materials from the biological oils.

Quantitation of Hydroperoxy‐, Keto‐ and Hydroxy‐Dienes During Oxidation of FAMEs from High‐Linoleic and High‐Oleic Sunflower Oils

AbstractThe objective of this work was to study the quantitative formation of hydroperoxydienes, ketodienes and hydroxydienes during autoxidation at 40 °C of fatty acid methyl esters derived from two sunflower oils with different degree of unsaturation, high‐linoleic sunflower oil and high‐oleic sunflower oil. The analysis of the oxidation compounds was carried out by NP‐HPLC–UV and results were compared to the specific extinction at 232 nm (K232) and the peroxide value (PV). Analysis of FAME polymers by HPSEC was also performed to discard samples of advanced oxidation. Results showed that the contents of hydroperoxydienes with respect to the PV were higher for the high linoleic (HL) sample. At the end of the period of slow polymerization (ΔPol ≤ 1 wt%), the content of hydroperoxydienes was found to be 86.0 and 30.7 μg/mg for the HL and high oleic (HO) samples, respectively. Throughout this period, hydroperoxydienes constituted around 90 and 50 wt% of the total hydroperoxides in the HL and HO samples, respectively, suggesting that a significant oxidation of oleic acid also occurred in both samples. The contents of ketodienes and hydroxydienes as a whole constituted 2–3 wt% of the diene compounds analyzed at the end of the period of slow polymerization. Higher contents of ketodienes than of hydroxydienes were found throughout the oxidation time, and the ratio between the contents of ketodienes and hydroxydienes increased with a factor that changed from 1 to 2 throughout the period of slow polymerization.

Synthesis of 2‐arylquinolin‐4(1H)‐ones and their transformation to N‐alkylated and O‐alkylated derivatives

Abstract magnified image2‐Aryl‐4‐quinolones are versatile synthetic intermediates and several articles continue to appear in literature describing their synthesis, chemical transformation, structural properties, and biological activities. Their versatility as synthetic intermediates is a consequence of 4‐quinolone moiety, which contains several reactive centers (positions 1, 3, and 4) for possible functionalization and can also enable different degree of unsaturation. In this review, we describe methods developed to‐date for the synthesis of 2‐arylquinolin‐4(1H)‐ones and their N‐alkylated and O‐alkylated derivatives. J. Heterocyclic Chem., 2010.

Hantupeptins B and C, cytotoxic cyclodepsipeptides from the marine cyanobacterium Lyngbya majuscula

Hantupeptins B (2) and C (3) were isolated, along with the previously reported hantupeptin A (1), from the marine cyanobacterium, Lyngbya majuscula, collected from Pulau Hantu Besar, Singapore. Their structures were elucidated by interpretation of extensive 1D and 2D NMR spectroscopic data. Compounds 2 and 3 are cyclic depsipeptides consisting of five alpha-amino/hydroxy acid residues, including phenyllactic acid, proline, N-methyl-valine, valine, N-methyl-isoleucine, and a beta-hydroxy acid unit with different degrees of unsaturation at the terminal end of each molecule. The absolute configurations of the common amino acids and phenyllactic acid were determined by the advanced Marfey's and chiral HPLC analyses, respectively. The complete stereochemistry of 3-hydroxy-2-methyl-7-octynoic acid moiety in hantupeptin A was elucidated by a combination of homonuclear J-resolved 2D NMR experiments and by Mosher's method. Hantupeptins B and C showed moderate in vitro cytotoxicity when tested against MOLT-4 (leukemic) and MCF-7 (breast cancer) cell lines.

Regulation of HMGCoA Reductase Activity by Policosanol and Octacosadienol, a New Synthetic Analogue of Octacosanol

Octacosa-10,19-dien-1-ol is a newly synthesized long-chain alcohol, an unsaturated analogue of 1-octacosanol, the major component of policosanol, the purified natural mixture of different higher aliphatic alcohols obtained from sugarcane wax. Our efficient synthetic protocol (five steps with 50% overall yield) is well suited for gram scale preparations and a rapid generation of analogues with different degrees of unsaturation. Beneficial effects of policosanol in the prevention of atherosclerosis and thromboembolic disorders have been reported and related to the inhibition of sterol biosynthesis possibly by the regulation of the activity of HMGCoA reductase mediated by AMP-dependent kinase AMPK. We have compared the effect of octacosadienol and policosanol on the regulation of HMGCoA reductase in HUVEC and HepG2 human hepatoma cells. Octacosadienol was as effective as policosanol in inhibiting the upregulation of HMGCoA reductase, in inducing the phosphorylation of AMPK and in downregulating the HMGCoA reductase mRNA.

Comparative effects of fatty acids on proinflammatory gene cyclooxygenase 2 and inducible nitric oxide synthase expression in retinal pigment epithelial cells

Dietary fat modification is a promising approach to prevent age-related macular degeneration (AMD). However, which types of fatty acids carry a greater risk for AMD remains unclear. In this study, we compared the effects of 18-carbon fatty acids with different degrees of unsaturation on the expression of the proinflammatory genes cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in human retinal pigment epithelium (RPE). Additionally, we investigated whether lutein could modulate these genes induced by fatty acids in RPE. Treatment with oleic acid, linoleic acid (LA), or linolenic acid increased the expression of iNOS and COX-2 genes and the production of prostaglandin E(2 )and nitric oxide (NO) in RPE, whereas the saturated fatty acid stearic acid had little effect on these genes. Of the fatty acids studied, LA had the greatest effects on the induction of these genes. Furthermore, LA also induced NF-kappaB transcriptional activation the most. Lutein inhibited LA-induced expression of COX-2 and iNOS in a dose-dependent manner. These data suggested that specific unsaturated fatty acids, particularly LA, can stimulate RPE cells to express proinflammatory genes, which may contribute to the pathogenesis of AMD. Lutein inhibited the expression of these genes induced by LA through blockade of NF-kappaB activation.

Relationship between changes in peroxide value and conjugated dienes during oxidation of sunflower oils with different degree of unsaturation

Peroxide value and the determination of conjugated dienes by UV absorption at 232 nm are normally applied alternatively for the evaluation of primary oxidation compounds. The objective of this study was to define the relationship between both indexes during oil oxidation in sunflower oils with different degree of unsaturation. The oils studied were conventional sunflower oil (SO) and high oleic sunflower oil (HOSO). For comparative purposes, methyl linoleate, whose hydroperoxides are conjugated diene hydroperoxides, was also studied. Samples were oxidized at 40 °C in the dark. In order to accelerate oxidation at 40 °C, the natural antioxidants present in the oils were removed, and a high surface to oil volume ratio (0.8 cm -1 ) was applied to guarantee total air availability. Linear regressions with high correlation coefficients between peroxide values and conjugated dienes were found for the three lipid systems studied (0.9988, 0.9991 and 0.9977 for methyl linoleate, SO and HOSO, respectively). Significant differences in the slopes of the lines were found (0.0974, 0.0854 and 0.0503 for methyl linoleate, SO and HOSO, respectively), indicating the formation of non-conjugated hydroperoxides from oleic acid in the oils, even in the oxidation of SO with a high degree of unsaturation. Consequently, only peroxide value would be reliable for the evaluation of primary oxidation compounds in oils of different degree of unsaturation, unless adequate calibration lines (peroxide value versus conjugated dienes) are applied.

The measurement of D/H ratio in alkenones and their isotopic heterogeneity

Abstract Previous paleoenvironmental studies reported the δD values of a mixture of coeluting alkenones. Here, we present a semi-preparative normal-phase high-performance liquid chromatography–mass spectrometry (NP-HPLC–MS) method for purifying long chain (C37 and C38) unsaturated methyl and ethyl ketones (alkenones) on the basis of chain length and degree of unsaturation. The method was applied to purify alkenones in suspended particles and surface sediments from a site in Chesapeake Bay, eastern USA. The hydrogen isotopic composition of di- and triunsaturated C37 and C38 alkenones differed significantly on the basis of chain length and the degree of unsaturation, demonstrating the importance of gas chromatography–isotope ratio-mass spectrometry (GC–irMS) analysis of individual alkenones for accurate paleoenvironmental reconstruction. Constant fractionation factors between alkenones with different chain length but the same degree of unsaturation ( α C 37 : 2 – C 38 : 2 and α C 37 : 3 – C 38 : 3 = 1.01 ) and those with the same chain length but different degree of unsaturation ( α C 37 : 2 – C 37 : 3 and α C 38 : 2 – C 38 : 3 = 0.97 ) in all samples suggest that the values may represent hydrogen isotope fractionation associated with elongation and desaturation during alkenone biosynthesis.

Effects of long chain fatty acid unsaturation on the structure and controlled release properties of amylose complexes

The addition of functional long chain (LC) unsaturated fatty acids to foods is often hampered by their instability. This study aimed to probe the possibility of using molecular inclusion complexes formed by amylose, termed V-amylose, as a possible solution for the delivery of long chain (LC) fatty acids to the consumer. X-ray diffraction, light scattering and atomic force microscopy (AFM) were employed to study the micro- and nano-structure of V-amylose hosting LC fatty acids with different degrees of unsaturation. Additionally, enzymatic digestion tests were conducted to assess the release of the fatty acids from the complexes. X-ray diffraction confirmed the formation of V-amylose while light scattering measurements, and the AFM images revealed that increased fatty acid unsaturation lead to the formation of bigger and more disperse particle populations. Enzymatic digestion tests with mammalian pancreatin illustrated the control over guest release which is induced by enzymatic hydrolysis. In conclusion, this study demonstrates that guest chemistry affects some of the functional properties of V-amylose for the delivery of LC fatty acids.

Formation of oxidation compounds in sunflower and olive oils under oxidative stability index conditions

AbstractThe objective of this work was to study the evolution of oxidation under oxidative stability index (OSI) conditions using the Rancimat apparatus. Sunflower oils with different degrees of unsaturation (conventional high‐linoleic sunflower oil, genetically modified high‐oleic sunflower oil, and a 1 : 1 mixture of both of them) and virgin olive oil were used. The sunflower oils were tested at 100 °C, while the olive oil was assayed at 100, 110 and 120 °C. Samples were analyzed at different time points and conductivity values, until the induction period (IP) was overpassed. A combination of adsorption and size‐exclusion chromatography was used for the quantification of oxidized triacylglycerol (TG) monomers, dimers and polymers. Additionally, peroxide values (PV) and ultraviolet absorption at 270 nm (K270), as well as losses of tocopherols, were measured. The results showed that oxidized TG monomers were the only group of oxidation compounds that increased during the early oxidation stage. The end of the IP was marked by the initiation of polymerization after the exhaustion of tocopherols. In comparison with reported results obtained at room temperature, the main difference found was that the amounts of oxidation compounds at the end of the IP were much lower at OSI test temperatures. With the exception of the K270 values, the results also showed that the IP endpoints provided by the OSI test were slightly higher than those obtained by quantification of oxidized TG monomers or by PV determination.

Emission of Volatile Aldehydes from DAG‐Rich and TAG‐Rich Oils with Different Degrees of Unsaturation During Deep‐Frying

AbstractThe purpose of the present study was to compare the emission of volatile aldehydes from diacylglycerol‐rich oils (DAG‐OILs) and triacylglycerol‐rich oils (TAG‐OILs) with different degrees of unsaturation of fatty acid moieties during the deep‐frying of sliced potatoes. To examine the effect of fatty acid composition, four kinds of oils with different fatty acid compositions were selected: rape seed (RS); sunflower oil as a high oleic (HO); safflower oil as high linoleic (HL); and, perilla oil as high linolenic (HLn) oils. The emissions of volatile aldehydes were determined during the deep‐frying of sliced potatoes by using the above fresh test oils or deteriorated RS oils. The statistical analysis showed no significant difference in volatile aldehyde emission and profile between the DAG‐OIL and TAG‐OIL with the fatty acid composition of RS, HL, and HLn. Although a statistically significant difference was noted in the volatile aldehyde emission between the DAG‐OIL and TAG‐OIL with HO, this difference was extremely small when compared to the variations found in the oils with four types of fatty acid composition. Finally, no difference was found in the volatile aldehyde emissions between the deteriorated DAG‐OIL and TAG‐OIL, although volatile aldehyde emissions increased with frying time. In addition, the acrylamide contents in potato chips prepared with RS–DAG or RS–TAG were at comparable levels.

A rapid method for determination of polar compounds in used frying fats and oils

The determination of polar compounds by adsorption chromatography is the most accepted method for the analysis of used frying fats due to its high precision and accuracy. However, this method is expensive and time consuming. In this study, a rapid analytical method to determine polar compounds is proposed. Starting from milligrams of sample dissolved in a solution of hexane containing methyl oleate as internal standard, the nonpolar fraction, which comprises the non-altered triglycerides (TG) and the internal standard, is obtained by solid phase extraction. Then, the non polar fraction is quantitatively analyzed in 15 min by high-performance size-exclusion chromatography (HPSEC) and the polar fraction is determined by difference of weight. Response factors for pure TG and FAME were calculated. Six samples of sunflower oils of different degrees of unsaturation were analyzed in triplicate and the results were compared with those obtained by the gravimetric method based on silica classical column chromatography. Results showed no significant differences between the two methods. In addition, the repeatability of the proposed method was excellent, as the coefficient of variation ranged from 1.5 to 13% depending on the contents of polar compounds.

Effects of ethanol on the remodeling of neutral lipids and phospholipids in brain mitochondria and microsomes

We have analyzed the effects of ethanol in vitro on the remodeling of neutral lipids and phospholipids in mitochondria and microsomes isolated from chick brain. We used three different fatty acyl-CoAs of similar chain lengths but different degrees of unsaturation. Our results demonstrate the existence of active mechanisms for acyl-CoA transfer into neutral lipids and phospholipids in both mitochondria and microsomes. The profile of fatty acid incorporation was clearly different according to the membrane and lipid fraction in question. Thus, in mitochondrial lipids, the remodeling processes showed a clear preference for the saturated fatty acid whilst the polyunsaturated one was the preferred substrate for microsomal lipid acylation. With regard to the effects of ethanol in vitro, we were able to demonstrate that exposure of the membrane to ethanol led to an increase in the incorporation of polyunsaturated fatty acid into triacylglycerol (TG) in both mitochondria and microsomes, indicating that it directly stimulates the acylation of diacylglycerol (DG) to give TG. This effect may then contribute to the widely reported stimulation of TG biosynthesis in cases of both acute and chronic ethanol ingestion. It is noteworthy that the exposure of microsomes to ethanol in vitro also stimulated the incorporation of oleoyl-CoA into the aminophospholipids phosphatidylethanolamine (PE) and phosphatidylserine (PS). We also demonstrate that both mitochondria and microsomes synthesize fatty acid ethyl esters (FAEEs) from fatty acyl-CoA, although there is a clear difference in preference for the fatty acid used as substrate in the esterification of the alcohol. Thus, mitochondria were capable of forming FAEEs from the polyunsaturated fatty acid whilst in microsomes the saturated fatty acid was the preferred substrate. In both types of membrane, FAEE production was lowest with the monounsaturated fatty acyl-CoA.

From chiral and prochiral N-allylpyrroles to stereodefined pyrrole fused architectures: A particular application of the rhodium-catalyzed hydroformylation

We review our recent results on the rhodium-catalyzed hydroformylation of chiral and prochiral N-allylpyrroles as a synthetic route to stereodefined 5,6-dihydro- and 5,6,7,8-tetrahydroindolizines. The indolizine nucleus at different degrees of unsaturation is a building block of natural and synthetic target compounds; thus new approaches, especially if stereoselective and/or stereospecific, are highly desirable. The construction of the indolizine architectures reported here occurs by formation of a C8–C9 bond through intramolecular cyclization of the 4-pyrrolylbutanal intermediate.

Synthesis and Characterization of New Polyurethane Adhesives

Polyurethane adhesives provide excellent flexibility, impact resistance and durability. Polyurethanes are formed through the reaction of an isocyanate component with polyether or polyester polyols or other active hydrogen compounds. This paper refers to polyurethane adhesives made from polyester polyols with long aliphatic chains (up to 36 carbon atoms) and MDI (diphenylmethane-4,4’-diisocyanate). The polyester polyols have been made from dimer acids obtained from renewable sources and short chain diols. The polyols that were used presented different degrees of unsaturation. The influence of the different raw materials in the adhesives performance is studied. The polyurethanes were produced by reaction between quasi-stoichiometric quantities of polyol and MDI, at several temperatures. The reaction was carried under inert atmosphere and at temperatures below 100°C. Performance of the adhesives was tested by carrying adhesion, hardness and water absorption tests. Characterization of both the polyester polyols and polyurethane adhesives was carried by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Magnetic Nuclear Resonance (NMR), X-Ray Diffraction (WAXD), Scanning RMN Imaging of 1H of Stray- Field b (MRI) and Brookfield viscometry.

Correlating chemical structure and physical properties of vegetable oil esters

AbstractThe influence of FA ester chemical structures on the rheology and crystallization temperature of those compounds was evaluated using methyl, n‐butyl, n‐octyl, and 2‐ethyl‐1‐hexyl FA esters with different chain lengths and different degrees of unsaturation. The rheological properties were analyzed in a high‐precision rheometer at various temperatures, and the crystallization temperatures were determined by DSC. Esters produced from the esterification of pure FA and from the transesterification of vegetable oils (i.e., soybean, corn, linseed, and babassu coconut oils) were evaluated. The length of the FA chain was shown to have a marked influence on the viscosity and crystallization temperature of the systems, whereas branching affected only the crystallization temperature to a significant extent. The viscosity and crystallization temperature of the systems were also influenced by the degree of unsaturation. One double bond was shown to increase viscosity, whereas two or three double bonds caused a decrease in the viscosity of the systems. Unsaturation lowered the crystallization temperature in all cases, regardless of the number of double bonds. From all the oils studied, methyl esters from babassu coconut oil presented the lowest crystallization temperatures.

Monitoring peroxide value in oxidized emulsions by Fourier transform infrared spectroscopy

Soybean oil (SBO) was blended with 10-40% palm kernel olein (PKO) to obtain SBO:PKO blends with different degrees of unsaturation. Oil-in-water (O/W) emulsions were then prepared with 70 wt-% of SBO or SBO:PKO blends and monitored for their chemical destabilization after an accelerated oxidation process up to 12 days at 60°C. The formation rate of hydroperoxides, as demonstrated by peroxide value (PV) evolution, throughout the oxidation period was relatively high for a fully SBO-based emulsion as compared to those with PKO incorporation. Fourier transform infrared (FTIR) spectroscopic method was also performed in parallel with PV determination, providing further information on structural changes of the functional groups due to lipid oxidation in the emulsions. By using a partial least square chemometric method, a developed calibration model that was based on the spectral region between 1800 and 1480 cm-1 was shown to be able to predict the PV in oxidized emulsions over the range of 4-45 meq/kg. With a 'leave-one-out' cross-validation optimization procedure, the calibration model provides a good coefficient of determination of 0.98 and a root mean standard error of cross-validation of 2.09. In general, FTIR spectroscopy is a suitable technique to monitor PV in oxidized emulsions. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.

Effects of antioxidants on the lipase‐catalyzed acidolysis during production of structured lipids

AbstractIn the production process of structured lipids, the influence of the addition of antioxidants before enzymatic acidolysis was investigated. Eight different antioxidants were screened: butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate, ascorbyl palmitate, citric acid, EDTA, a tocopherol blend and lecithin. As substrates, oils with different degrees of unsaturation (rapeseed, safflower or fish oil) as well as caprylic and capric acids were used. Enzyme activity (measured as percent incorporation of caprylic/capric acid into the oils) was not significantly influenced by the addition of antioxidants, neither in a batch process nor in a packed‐bed reactor operation. α‐Tocopherol concentrations remained stable for those mixtures where tocopherols were added. Primary oxidation products (measured as peroxide values) were reduced after acidolysis in the packed‐bed reactor, likely due to the adsorption in the enzyme bed. The study shows that the addition of antioxidants before enzymatic reactions has no negative effects on the reaction progress. None of the antioxidants chosen had a significant positive effect on either the reaction process or the oxidative status of the structured lipid produced.

Molecular and isotopic characterization of lipids in cultured halophilic microorganisms from the Dead Sea and comparison with the sediment record of this hypersaline lake

Cultures of the only photosynthetic green alga ( Dunaliella parva) in the surface waters of the Dead Sea and three halophilic archaea ( Haloarcula marismortui; Haloferax volcanii; Halorubrum sodomense) from the same location were analyzed for their lipid content to investigate the contribution of these organisms to the organic matter in the sediments of this hypersaline lake. Based on distribution patterns and stable carbon isotope ratios, most of the sedimentary short chain saturated and unsaturated fatty acids may be attributed to the green alga, whereas the relatively abundant long chain acids are considered to be predominantly of allochthonous origin. Two Δ 7 sterols in the sediments also occur in the alga. Based on carbon isotope data, sedimentary phytol probably has a mixed origin, whereas n-alkanols and n-alkanes were contributed to the sediments from terrestrial sources. The extractable lipid compositions of the three archaea are very similar and dominated by squalenes with different degrees of unsaturation and by glycerol diphytanyl diether (archaeol). Whereas archaeol is also a major constituent of the extractable organic matter in the sediments, the squalenes apparently do not survive sedimentation unaltered; the same is true for the small amounts of less common unsaturated analogues of archaeol in the archaea.

Soybean Oil Based Greases: Influence of Composition on Thermo-oxidative and Tribochemical Behavior

The biodegradable properties and lubricating ability of greases depend on both the base oil and the thickener. Mineral oils are the most widely used lubricant base fluids due to their inherent lubricity and low cost, but recent environmental awareness has forced consideration of the use of biodegradable fluids such as vegetable oils and certain synthetic fluids in grease formulations. This study presents data on the thermo-oxidation behavior and tribology of biodegradable greases formulated with soybean oil and different compositions of metal soap thickener. The composition of thickener has been varied by using fatty acids with different degrees of unsaturation and fatty acids of different chain lengths. The improvement of thermo-oxidation and tribological properties as a result of changing thickener/base oil ratio and the antioxidative effect of some suitable additives have also been evaluated.