Polyunsaturated Fatty Esters Research Articles

Dose-Response Effects of 7-Dehydrocholesterol Reductase Inhibitors on Sterol Profiles and Vesicular Stomatitis Virus Replication.

Cholesterol is ubiquitous in cells; it plays a critical role in membrane structure and transport as well as in intracellular trafficking processes. There are suggestions that cholesterol metabolism is linked to innate immunity with inhibitors of DHCR7, the last enzyme in the cholesterol pathway, suggested to have potential as viral therapeutics nearly a decade ago. In fact, there are a number of highly prescribed pharmaceuticals that are off-target inhibitors of DHCR7, causing increased cellular levels of 7-dehydrodesmosterol (7-DHD) and 7-dehydrocholesterol (7-DHC). We report here dose-response studies of six such inhibitors on late-stage cholesterol biosynthesis in Neuro2a cells as well as their effect on infection of vesicular stomatitis virus (VSV). Four of the test compounds are FDA-approved drugs (cariprazine, trazodone, metoprolol, and tamoxifen), one (ifenprodil) has been the object of a recent Phase 2b COVID trial, and one (AY9944) is an experimental compound that has seen extensive use as a DHCR7 inhibitor. The three FDA-approved drugs inhibit replication of a GFP-tagged VSV with efficacies that mirror their effect on DHCR7. Ifenprodil and AY9944 have complex inhibitory profiles, acting on both DHCR7 and DHCR14, while tamoxifen does not inhibit DHCR7 and is toxic to Neuro2a at concentrations where it inhibits the Δ7-Δ8 isomerase of the cholesterol pathway. VSV itself affects the sterol profile in Neuro2a cells, showing a dose-response increase of dehydrolathosterol and lathosterol, the substrates for DHCR7, with a corresponding decrease in desmosterol and cholesterol. 7-DHD and 7-DHC are orders of magnitude more vulnerable to free radical chain oxidation than other sterols as well as polyunsaturated fatty esters, and the effect of these sterols on viral infection is likely a reflection of this fact of Nature.

Partial Hydrogenation of Soybean and Waste Cooking Oil Biodiesel over Recyclable-Polymer-Supported Pd and Ni Nanoparticles

Biodiesel obtained through the transesterification in methanol of vegetable oils, such as soybean oil (SO) and waste cooking oil (WCO), cannot be used as a biofuel for automotive applications due to the presence of polyunsaturated fatty esters, which have a detrimental effect on oxidation stability (OS). A method of upgrading this material is the catalytic partial hydrogenation of the fatty acid methyl ester (FAME) mixture. The target molecule of the partial hydrogenation reaction is monounsaturated methyl oleate (C18:1), which represents a good compromise between OS and the cold filter plugging point (CFPP) value, which becomes too high if the biodiesel consists of unsaturated fatty esters only. In the present work, polymer-supported palladium (Pd-pol) and nickel (Ni-pol) nanoparticles were separately tested as catalysts for upgrading SO and WCO biodiesels under mild conditions (room temperature for Pd-pol and T = 100 °C for Ni-pol) using dihydrogen (p = 10 bar) as the reductant. Both catalysts were obtained through co-polymerization of the metal containing monomer M(AAEMA)2 (M = Pd, Ni; AEEMA− = deprotonated form of 2-(acetoacetoxy)ethyl methacrylate)) with co-monomers (ethyl methacrylate for Pd and N,N-dimethylacrilamide for Ni) and cross-linkers (ethylene glycol dimethacrylate for Pd and N,N’-methylene bis-acrylamide for Ni), followed by reduction. The Pd-pol system became very active in the hydrogenation of C=C double bonds, but poorly selective towards the desirable C18:1 product. The Ni-pol catalyst was less active than Pd-pol, but very selective towards the mono-unsaturated product. Recyclability tests demonstrated that the Ni-based system retained its activity and selectivity with both the SO and WCO substrates for at least five subsequent runs, thus representing an opportunity for waste biomass valorization.

Enzymatic synthesis of vanillin and related catalytic mechanism

AbstractThere has been an increasing demand for bio vanillin for a variety of applications. Although vanillin production using biotechnological methods based on microbial fermentation has been extensively explored, the use of isolated enzymes for vanillin synthesis has not yet attracted much attention. Lipoxygenase (LOX) is an iron‐containing dioxygenase well known for catalysing the hydroperoxidation of polyunsaturated fatty acids and esters. Its newly discovered ability to catalyse the oxidative cleavage of isoeugenol to vanillin offers a promising solution for synthesizing bio vanillin. In this study, soybean LOX was used as the catalyst for vanillin synthesis. The reaction was optimised by examining the effects of pH, temperature, substrate concentration, and enzyme dosage. By investigating the impact of various additives, including two denaturants, seven chelators, six surfactants, 10 organic solvents, eight deep eutectic solvents, and 13 natural deep eutectic solvents, it was found that denaturants (urea and guanidine) and some chelators (e.g. ethylenediaminetetraacetic acid, EDTA) are effective in improving synthetic yields, by up to 133 and 406%, respectively, relative to the additive‐free reaction system. Two free‐radical catalytic mechanisms were proposed to explain the new activity of the enzyme for vanillin synthesis.

Synthesis of polyunsaturated fatty boronic esters and their in vitro inhibition to HCT116 cell lines

Five polyunsaturated fatty boronic esters (PUFB) were synthesized using a photoinduced decarboxylative borylation reaction from corresponding polyunsaturated fatty acids (PUFA) and in vitro anti-proliferation activity of these molecules on HCT116 cell lines was tested. The yield of the photoinduced decarboxylative borylation reaction was negatively correlated with the number of double bonds in PUFA. Additionally, application of vacuum to the reaction significantly improved the yield. All PUFBs showed anti-proliferation effect on HCT116 cell lines and the mixture of the 5 PUFBs showed higher toxicity than each individual PUFB. Again, the cytotoxicity was positively correlated with number of double bonds. Furthermore, PUFBs showed weaker anticancer activity than the corresponding PUFAs and this is tentatively attributed to the change of antioxidant potency and we categorize PUFBs to “secondary antioxidants”. We hope our findings deepen the understanding of photoinduced decarboxylative borylation reaction and provide further insights to the design of PUFA based bioactive molecules.

Fast Fourier infrared spectroscopy to characterize the biochemical composition in diatoms

Diatoms are photosynthetic unicellular microalgae and are nature's hidden source of several biosynthetic metabolites with their use in biofuel, food and drug industries. They mainly contain various lipids, sterols, isoprenoids and toxins with their use in apoptotic, fertility controlling and cancer drugs. Chemical studies on diatoms are limited due to various limitations such as variation of nutrients, contaminants and change in seasonal factors in the environment. To overcome these limitations, we obtained axenic cultures of 12 fresh-water diatom strains on the 22nd day of inoculation having a dry weight of 1 mg each and performed their Fourier transform infrared (FTIR) study for the detection of functional groups responsible for their chemical moiety. The spectral mapping showed a varied level of polyunsaturated fatty acids, amides, amines, ketone bodies and esters for their applications in various pharmacological, food and biofuel industries in the exponential phase of their growth in f/2 media. The FTIR study of the 12 diatom strains showed various similarities in the form of some common peak patterns ranging from 3000 to 3600 cm-1 for vO-H absorption. The symmetric stretching vibration frequency of Diadesmis confervaceae (V2) type species showed different behaviour than others in the spectral region starting from 1600 to 1700 cm-1. The absorption between 1500 and 1575 cm-1 reflects the presence of the -N-H group. Infrared (IR) absorptions falling between 1600 and 1700 cm-1 reflect the presence of amide's vC=O in all species. Placoneis elginensis (V8) type species showed an additional absorption band which is centred around 1735-1750 cm-1 which perhaps reflects the presence of ester's vC=O. Diadesmis confervaceae (V2), Nitzschia palea (V4), Placoneis elginensis (V8), Nitzschia palea var. debilis (V6), Nitzschia inconspicua (V10), Gomphonema parvulum (V11) and Sellaphora (V12) showed distinct structural features with important key functionalities that can make them essential drug markers in the pharmaceutical industry.

Bio-lubricants production from fish oil residue by transesterification with trimethylolpropane

The fatty acid ethyl esters mixture, a fish oil residue obtained after the extraction of omega-3 polyunsaturated fatty esters, has been converted into mixtures of mono-, di-, and triesters of trimethylolpropane by transesterification at 100-140 °C under vacuum with sodium ethoxide as catalyst. This method has shown to be more efficient than the enzymatic transesterification using commercially available lipases. The crude reaction mixture (84% conversion of ethyl esters), enriched in trimethylolpropane triesters (96% selectivity) was characterized and its properties compared with those of the starting ethyl esters mixture and the trimethylolpropane esters obtained from vegetal sources.

Effect of microheterogeneity on the kinetics of oxidation of methyl linoleate in micelles

The kinetic results of the radical chain oxidation of methyl linoleate (LH) in micelles were given. The oxidation rate depends on the average number of substrate molecules in the micelle and is almost independent of the micelle concentration under the given conditions. The chain propagation and termination were assumed to predominantly occur inside the micelle. Possible reasons for linear chain termination during the oxidation of polyunsaturated fatty esters in microheterogeneous systems were discussed.

Antioxidants from stem bark of Kigelia africana inhibits free radicals and membrane lipid damage in rat testes in vitro

Objective: Bioactive ingredients of plants have been used as a central source of medicine and chemo-therapies for centuries. Nevertheless, the quantification and characterization of phytochemicals in methanol extract stem bark of Kigelia africana (MESBKA) will be highly advantageous if found affirmative. Methods: MESBKA was taken for gas chromatography-mass spectrometry (GC-MS) analysis. Thereafter, its effect on pro-oxidant induced hydroxyl radical and lipid peroxidation in rat’s testes was evaluated. Results: The GC-MS analysis provided four peaks of eighteen different active compounds. Also, MESBKA contains antioxidants (polyunsaturated fatty acids, esters and poly alcohols) which are prophylactics of hydroxyl radicals and inhibitors of cyclooxygenase-2 (COX-2) in the testes. Furthermore, MESBKA inhibited pro-oxidants induced hydroxyl radicals and lipid peroxidation in rat’s testes in a dose-dependent manner. Conclusion: The antioxidant content of Kigelia africana could have prevented inflammatory responses to enhance male fertility in rat. Isolation and translation of individual components of the plant would help to find new drugs to cure and/or prevent male infertility.

NMR techniques for determination of lipid content in microalgal biomass and their use in monitoring the cultivation with biodiesel potential.

In the present investigation, the application of NMR spectroscopic techniques was extensively used with an objective to explore the biodiesel potential of biomass cultivated on a lab scale using strains of Chlorella vulgaris and Scenedesmus ecornis. The effect of variation in the composition of culturing medium on the neutral and polar lipids productivity, and fatty acid profile of solvent extracts of microalgae biomass was studied. Determination of unsaturated fatty acid composition (C18:N = 1-3, ω3 C20:5, ω3 C22:6), polyunsaturated fatty esters (PUFEs), saturated fatty acids (SFAs), unsaturated fatty acids (UFAs), free fatty acids (FFAs), and iodine value were achieved from a single (1)H NMR spectral analysis. The results were validated by (13)C NMR and GC-MS analyses. It was demonstrated that newly developed methods based on (1)H and (13)C NMR techniques are direct, rapid, and convenient for monitoring the microalgae cultivation process for enhancement of lipid productivity and their quality aspects in the solvent extracts of microalgal biomasses without any sample treatment and prior separation compared to other methods. The fatty acid composition of algae extracts was found to be similar to vegetable and fish oils, mostly rich in C16:0, C18:N (N = 0 to 3), and n-3 omega polyunsaturated fatty acids (PUFAs). The lipid content, particularly neutral lipids, as well as most of the quality parameters were found to be medium specific by both the strains. The newly developed methods based on NMR and ultrasonic procedure developed for efficient extraction of neutral lipids are cost economic and can be an effective aid for rapid screening of algae strains for modulation of lipid productivity with desired biodiesel quality and value-added products including fatty acid profile.

A Comprehensive Evaluation of the Density of Neat Fatty Acids and Esters

AbstractDensity is one of the most important physical properties of a chemical compound, affecting numerous applications. An application in the case of fatty acid esters (biodiesel) is that density is specified in some biodiesel standards. In the present work, the density of fatty acid methyl, ethyl, propyl, and butyl esters as well as triacylglycerols in the C8–C24 range was determined in the range of 15–40 °C with a densitometer utilizing the oscillating U‐tube technique. Literature data on density are compiled and compared, showing that data for these compounds are incomplete with discrepancies existing in some cases. Besides known effects such as density decreasing with increasing chain length and increasing saturation, it is shown that trans fatty compounds exhibit lower density than cis fatty compounds. Density data for several saturated odd‐numbered, C18, as well as C20 and C22 polyunsaturated fatty esters are reported for the first time. The density contribution of compounds with high melting points is predicted. An equation is given for the calculation of the density of mixtures.

Biodiesel Potential of Oleaginous Yeast Biomass by NMR Spectroscopic Techniques

Analytical strategies based on NMR (1H and 13C), IR (infrared), and GC (gas chromatography) techniques have been developed for the molecular level characterization of Soxhlet and ultrasonic solvent extracts of yeast biomass samples generated on a lab scale by different yeast, feed, and diverse culture conditions, with an objective to explore biodiesel potential. The extraction efficiency of each solvent (cyclohexane, chloroform, methanol) toward extraction of neutral lipids (total glycerides (TG), free fatty acids (FFA), and polar lipids have been determined and compared with regards to the nature of fatty acid components extracted in each solvent fractions. The fatty acid composition of yeast extracts has been found to be similar to vegetable oils, mostly rich in C16:0, 18:0, and C18:N (N = 1–3) fatty acids as indicated by the combined NMR, GC, and GC-MS analyses. The analytical protocol developed has established that 1H NMR techniques can be used directly and rapidly without any sample treatment and prior separation to determine total neutral lipid content (TG, FFA), nature of fatty acids/ester, polyunsaturated fatty esters (PUFE), iodine value, etc. NMR results of nature of unsaturated fatty acids/esters (C18:N, N = 1–3) have been validated by GC and GC-MS analyses. The results have shown the presence of C18:1 and C18:2 as the predominant unsaturated fatty acid components besides common saturated fatty acids. The content and composition of biomass has been found to be specific to types of yeast and feed used for cultivation. The NMR methods offer great potential for rapid screening of yeast for generation of yeast biomass with desired lipid content, quality, and biodiesel potential and value added PUFE, keeping in view of the cost economics of overall generation cost of the biomass.

Influence of blending vegetable oil methyl esters on biodiesel fuel properties: Oxidative stability and cold flow properties

Properties of biodiesel can be related to the chemical composition of the biomass source used in transesterification. Saturated fatty acids confer high oxidative stability, while unsaturated fatty acids improve the cold flow properties, which are also influenced by the chain length. In the present study, blends of biodiesel produced from different vegetable oils were evaluated in order to obtain the proper blend to fulfill the European Standard EN14214 in terms of oxidative stability and cold flow properties. Citric acid was used to purify the methyl ester phase. Oxidative stability resulted highly dependent on polyunsaturated fatty esters while fatty ester chain length is a determining factor in cold flow performance of the blends. A preliminary study of the effectiveness of a commercial additive (a Poly alkyl methacrylate) in improving methyl ester flow at low temperatures was done, but no significant changes were found.

A highly efficient, green and recoverable catalytic system for the epoxidation of fatty esters and biodiesel with H2O2

A highly efficient and green strategy for the epoxidation of fatty esters, combining a green oxidant (aqueous hydrogen peroxide) and a recyclable catalyst (a seleninic acid derivative) is presented. The possibility of integrating renewable solvents derived from glycerol in the productive cycle of biodiesel commodities is also explored. Fluorinated solvents (both commercial and glycerol-derived) play a double key role on this methodology: on the one hand, they strongly accelerate epoxidation reaction with respect to common non-fluorinated solvents and, on the other hand, some of them allow catalyst recycling. Mono- and polyunsaturated fatty esters, as well as soy biodiesel have been epoxidized with excellent yields and selectivities towards epoxide under the optimal conditions and with minimum catalyst loads.

Preparation of fatty acid methyl esters from hazelnut, high-oleic peanut and walnut oils and evaluation as biodiesel

Refined hazelnut, walnut and high-oleic peanut oils were converted into fatty acid methyl esters using catalytic sodium methoxide and evaluated as potential biodiesel fuels. These feedstocks were of interest due to their lipid production potentials (780–1780Lha−1yr−1) and suitability for marginal lands. Methyl oleate was the principal constituent identified in hazelnut (HME; 76.9%) and peanut (PME; 78.2%) oil methyl esters. Walnut oil methyl esters (WME) were comprised primarily of methyl esters of linoleic (60.7%), oleic (15.1%) and linolenic (12.8%) acids. PME exhibited excellent oxidative stability (IP 21.1h; EN 14112) but poor cold flow properties (CP 17.8°C) due to its comparatively high content of very-long chain fatty esters. WME provided low derived cetane number and oxidative stability (IP 2.9h) data as a result of its high percentage of polyunsaturated fatty esters. HME yielded a satisfactory balance between all fuel properties when compared to the biodiesel standards ASTM D6751 and EN 14214 due to its high content of monounsaturated fatty esters. Also explored were the properties of blends of HME, PME and WME in ultra-low sulfur (<15ppm) diesel (ULSD) fuel and comparison to petrodiesel standards ASTM D975, D7467 and EN 590. With increasing content of biodiesel, the oxidative stability, cold flow properties and calorific value of ULSD was negatively affected, whereas lubricity was markedly improved. Kinematic viscosity, specific gravity and surface tension were impacted to lesser extents by addition of biodiesel to ULSD. In summary, HME, PME and WME are suitable based on their fuel properties as biodiesel fuels and blend components in ULSD.

Determination of Polyunsaturated Fatty Esters (PUFA) in Biodiesel by GC/GC–MS and 1H‐NMR Techniques

AbstractIn the present work, methods based on Gas Chromatography (GC), Gas Chromatography–Mass Spectrometry (GC–MS) and 1H‐NMR techniques was developed for the characterization and estimation of Polyunsaturated Fatty Esters (PUFA) in biodiesel. The GC method enables the separation, identification and estimation of these polyunsaturated fatty acid methyl esters to be carried out using a highly polar capillary column (100% cyanopropyl silicon). GC–MS was utilized for unambiguous identification and estimation of esters and isomers present in biodiesel. The estimation of PUFA content is important because PUFA content is a part of the EN 14214 specifications of biodiesel. There is no existing standard method for the estimation of total PUFA content in biodiesel. The developed GC method also quantifies EPA and DHA (C20:5 and C22:6) fatty acid methyl esters which can be used as markers for the estimation of fish oil biodiesel. The presence of EPA and DHA indicates the contamination of fish oil in biodiesel. Further, the 1H‐NMR technique has also been employed to identify and estimate PUFA containing ≥3 double bonds. The PUFA content was estimated from the integral intensities of the chemical shift region corresponding to all type of double bonds in the 1H‐NMR spectra. Based on the developed method, GC fingerprinting of various biodiesel samples was carried out to estimate a PUFA content as low as 1,000 ppm.

Impaired Microsomal Oxidation of the Atypical Antipsychotic Agent Clozapine in Hepatic Steatosis

Hepatic lipid infiltration (steatosis) is a complication of the metabolic syndrome and can progress to nonalcoholic steatohepatitis and severe liver injury. Microsomal cytochrome P450 (P450) drug oxidases are down-regulated in experimental steatosis. In this study we evaluated the separate and combined effects of lipid accumulation and P450 down-regulation on the microsomal oxidation of the antipsychotic agent clozapine (CLZ), the use of which is associated with an increased incidence of the metabolic syndrome. Several important drug oxidizing P450s were down-regulated, and the formation of N-desmethyl-CLZ (norCLZ) and CLZ N-oxide was decreased in microsomal fractions from orotic acid-induced early steatotic rat liver. Inclusion of lipids extracted from steatotic, but not control, liver decreased the free concentration of CLZ in microsomes and suppressed norCLZ formation; CLZ N-oxidation was unchanged. Triglycerides increased in steatotic liver to 15-fold of control, whereas increases in the monounsaturated oleic acid to 10-fold of control and total polyunsaturated and saturated fatty acids to 4- and 5-fold of control also occurred. Addition of triglycerides containing esterified omega-6 and omega-3 fatty acids inhibited the microsomal formation of norCLZ but not that of CLZ N-oxide; triglycerides esterified with unsaturated and monounsaturated fatty acids were inactive. Thus, drug oxidation may be suppressed in steatosis by P450 down-regulation and the accumulation of polyunsaturated fatty esters. In contrast, the activity of the flavin-containing monooxygenase that mediates CLZ N-oxidation was unimpaired. Lipid deposition in livers of patients with the metabolic syndrome may necessitate dosage adjustments for toxic drugs, including CLZ.

Mechanisms of the aerobic oxidations catalyzed by N-hydroxyderivatives : Enthalpic, polar and solvent effects, “molecule-induced homolysis” and synthetic involvements

Aminoxyl (R 2N O ), amidoxyl (RCO N(O ) R) and imidoxyl ((RCO) 2N O ) radicals play a key role in the aerobic oxidation catalyzed by N-hydroxyderivatives. The rationalization of the mechanisms of a variety of oxidations is based on thermochemical, kinetic and spectroscopic investigations and on solvent effects and it has suggested new selective synthetic developments. In collaboration with CIBA Speciality Chemicals a new catalytic system resulting from the combination of a persistent macrocyclic aminoxyl radical and the couple Mn(NO 3) 2/Co(NO 3) 2 has been developed; it is particularly effective for the aerobic oxidation of alcohols to aldehydes and ketones under mild conditions (air at room temperature and atmospheric pressure); above all it presents the great advantage of an easy recovery and recycling providing the possibility of practical applications. The kinetic investigation of the substituent effect in the oxidation of benzyl alcohols has allowed identifying the rate-determining step of the oxidation. The amidoxyl radicals, generated “in situ” from N-hydroxyamide, revealed particularly effective catalysts for the aerobic peroxidation of polyunsaturated fatty acids and esters, which is involved in the origin of several important pathologies, such as tumor initiation and atherosclerosis. The kinetic investigation has contributed to explain the mechanism of the oxidation and to develop the most effective methodology for the synthesis of hydroperoxides. The importance of enthalpic, polar, captodative, solvent effects and “molecule-induced homolysis” has been emphasized in the oxidation, halogenation and acetoxylation of a variety of classes of organic compounds (hydrocarbons, alcohols, aldehydes, amines, amides, silanes) by O 2 and N-hydroxyimide catalysis. The high selectivity often observed and the very mild experimental conditions, based on the mechanistic interpretation, provide industrial potentiality to the catalytic processes.

Identification of Residues Responsible for Ligand Recognition and Regioisomeric Selectivity of Lysophosphatidic Acid Receptors Expressed in Mammalian Cells

The endothelial differentiation gene family encodes three highly homologous G protein-coupled receptors for lysophosphatidic acid (LPA). Based on baculoviral overexpression studies, differences have been proposed in the structure-activity relationship (SAR) of these receptors. We have compared the SAR of the individual receptors either overexpressed transiently at high or at lower levels following stable transfection in LPA-nonresponsive RH7777 cells. The SAR in transfected RH7777 cells was markedly different from that described in insect cells. The LPA(3) receptor has been proposed to be selectively activated by unsaturated LPA species and shows a strong preference for sn-2 versus the sn-1 acyl-LPA regioisomer. Because of the short half-life of sn-2 LPA due to acyl migration under some conditions, we have synthesized acyl migration-resistant analogs using an acetyl group in place of the free hydroxyl group in order to evaluate LPA receptor SAR. Only LPA(1) and LPA(2) showed regioisomeric preference and only for the 18:2 fatty acyl-stabilized LPA sn-1 regioisomer. To identify residues involved in ligand recognition of LPA(3), we developed and validated computational models of LPA(3) complexes with the analogs studied. The models revealed that Arg-3.28 and Gln-3.29 conserved within the LPA-selective endothelial differentiation gene receptors and the more variable Lys-7.35 and Arg-5.38 of LPA(3) form critical interactions with the polar headgroup of LPA. The models identified Leu-2.60 and Val-7.39 of LPA(3) underlying the regioisomer-selective interaction with the acetyl group of the stabilized regioisomers. Mutation of Leu-2.60 to alanine selectively increased the EC(50) of the sn-2 acetyl-LPA regioisomers, whereas alanine replacement of Val-7.39 profoundly affected both regioisomers.

Polymorphism of the pig 2,4-dienoyl CoA reductase 1 gene (DECR1) and its association with carcass and meat quality traits1

We characterized the nearly complete coding sequence of the pig 2,4-dienoyl CoA reductase 1 (DECR1) gene, which encodes an enzyme involved in the beta-oxidation of polyunsaturated fatty enoyl-CoA esters and maps on a linoleic QTL located on Chromosome 4. Sequencing of a 937-bp fragment encompassing exons 2 and 10 revealed the existence of two missense SNP at exon 2 (C181 --> G181) and exon 5 (C458 -->G458). These two SNP are associated with Val (C) --> Leu (G) and Ser (C) --> Thr (G) conservative AA replacements at positions 61 and 153 of the DECR1 protein, respectively. Moreover, DECR1 genotyping in a representative sample of 184 pigs from the Large White, Pietrain, Iberian, Duroc, and Landrace breeds demonstrated the existence of disequilibrium linkage between these two SNP (Haplotype 1: C181C458; Haplotype 2: G181G458). An association analysis between DECR1 genotype and growth, carcass, and meat quality traits in a highly selected Landrace population (n = 470) revealed differences among genotypes for isocitrate dehydrogenase activity (highest posterior density [HPD] of 90%), longissimus thoracis pH (HPD of 95%), lightness (HPD of 90 to 95%), and redness (HPD of 95%). Because these associations were not consistently found in the three available genotype comparisons, we believe that exon 2 and 5 polymorphisms at the DECR1 gene might be in linkage disequilibrium with the true causal mutation influencing isocitrate dehydrogenase activity and muscle color and pH.

The metathesis of polyunsaturated fatty esters using the homogeneousW(O-2,6-C6H3X2)2Cl4/Me4Sn catalytic systems

Abstract Promoted with a small amount of Me4Sn, W(O-2,6-C6H3X2)2Cl4 (X=Ph, Cl) complexes are highly active metathesis catalysts for polyunsaturated fatty esters. Upon metathesis of methyl linoleate, substrate conversions of ca. 95 and 78% were obtained in 2 h with the W(O-2,6-C6H3Ph2)2Cl4/Me4Sn and W(O-2,6-C6H3Cl2)2Cl4/Me4Sn catalytic systems respectively. The lower activity of the W(O-2,6-C6H3Cl2)2Cl4/Me4Sn catalytic system was attributed to the highly deactivating nature of the Cl substituents on the o,o′-position of the aryloxide ligand. Highly electron-withdrawing Cl substituents cause the tungsten atom to be electron-deficient and thus more susceptible to attack by the electron-rich ester groups. However, the W(O-2,6-C6H3Cl2)2Cl4/Me4Sn system was more selective towards dicarboxylic esters. The latter are interesting starting materials for the synthesis of polyesters and polyamides. The W(O-2,6-C6H3X2)2Cl4/Me4Sn catalytic systems were rapidly deactivated by bromine-containing olefinic esters. Deactivation was attributed to a side reaction between the Br-group and the electron-deficient W-centre.