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1.
Esters of l-ascorbic acid with long-chain fatty acids (E-304) are employed as antioxidants in foods rich in lipids. Although their enzymatic synthesis offers some advantages compared with the current chemical processes, most of the reported methods employ the immobilized lipase from Candida antarctica as biocatalyst and free fatty acids or activated esters as acyl donors. In order to diminish the cost of the process, we have investigated the synthesis of ascorbyl oleate and ascorbyl palmitate esters with the immobilized Thermomyces lanuginosus lipase Lipozyme TL IM—which is significantly less expensive than Novozym 435—and triglycerides as source of fatty acids. Lipozyme TL IM gave rise to a lower yield of 6-O-ascorbyl oleate than Novozym 435 when using triolein (64 vs. 84%) and olive oil (27 vs. 33%) as acyl donors. Both 6-O-ascorbyl oleate and 6-O-ascorbyl palmitate displayed excellent surfactant and antioxidant properties. The Trolox Equivalent Antioxidant Capability values for the oleate and palmitate were 71 and 84%, respectively, of those obtained with l-ascorbic acid; however, both derivatives were able to stabilize soybean oil towards peroxide formation.  相似文献   

2.
Enzymatic synthesis of fatty acid glucose esters from different fatty acyl donors are performed via enzymatic catalysis in the presence of Candida antarctica lipase B (CALB), using acetonitrile as the solvent. The acyl donor nature (fatty acid or fatty acid vinyl ester) and structure are varied. Lower reaction rates and lower conversions are obtained with fatty acids in comparison to their corresponding vinyl esters. Moreover, the acyl donor with the longest chain length gives the highest conversions. The presence of unsaturation on the acyl donor chain is also shown to be detrimental to the conversion. Practical Applications: The practical applications of the present work are related to the production of gluco‐esters that could be used as nonionic surfactants as detergents, cosmetics and food emulsifiers, emollients or conservatives, respectively. In this study, it is shown that in order to get high production yields, each reaction parameter has to be tuned properly.  相似文献   

3.
Oxidative stability of lipids is one of the most important parameters affecting their quality. Lipase‐catalyzed lipophilic tyrosyl esters with an equivalent carbon alkyl chain but different degrees of unsaturation (C18:0 to C18:4n3) were prepared, characterized, and used as antioxidants. Free fatty acids and fatty acid ethyl esters (substrate molar ratio tyrosol: acyl donor, 1:10) were used as acyl donors and immobilized lipase from Candida antarctica was the biocatalyst (10 %). The phenolipids were isolated and characterized using ESI–MS, 1H‐NMR, and 13C‐NMR. Peroxide value (PV) and para‐anisidine value (p‐AV) were measured to evaluate their antioxidant activities in bulk oil structured lipid (SL) and in an oil‐in‐water emulsion (SL‐based infant formula). No significant difference was found in yield and reaction time between the two types of acyl donors. However, as the unsaturation of the fatty acids increased the reaction time also increased. In SL, tyrosyl esters exhibited lower antioxidant activity than tyrosol whereas the addition of an alkyl chain enhanced the antioxidant efficiency of tyrosol in infant formula. Tyrosyl oleate was the most efficient antioxidant in the emulsion system followed by tyrosyl stearate and tyrosyl linoleate. These results suggest that the synthesized phenolipids may be used as potential antioxidants in lipid‐based products.  相似文献   

4.
Antioxidative properties and enzymatic synthesis of ascorbyl FA esters   总被引:3,自引:0,他引:3  
Efficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants in t-amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl-activated acyl donors (71, 80, and 86% yields of esters with FA excesses of 1∶1, 1∶1.5, and 1∶2, respectively). As very low water activity is needed to achieve sufficiently high yields of product, molecular sieves were used to improve the ascorbyl ester yields. Ascorbyl oleate is more amorphous and has a much lower m.p. and lower enthalpy of fusion than ascorbyl palmitate. This leads to a higher solubility of ascorbyl oleate in oil, resulting in an increased antioxidant effect compared to that of the palmitate. In an accelerated storage test using deodorized rapeseed oil, samples incubated with ascorbyl palmitate showed noticeable oxidation after 1 wk of storage, whereas samples incubated with ascorbyl oleate displayed negligible oxidation for 9 and 4 wk at 30 and 40°C, respectively.  相似文献   

5.
Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30°C. The products were analyzed by gas chromatography. The yield of monoesters was affected by the acyl donors, organic solvents, temperature, water content, pH memory and reaction time. The anhydrous (lyophilized) enzyme and fatty acid anhydrides were best for monoester production. The optimum pH ranges were 4–5 and 8–10. The yields of propylene glycol monolaurate, monomyristate, monopalmitate, monostearate and monooleate with 50 mM fatty acid anhydrides as acyl donors were 97.2, 79.6, 83.7, 89.7 and 93.4 mM, respectively; those with 50 mM fatty acids as acyl donors were 37.3, 28.7, 28.7, 35.3 and 36.2 mM, respectively. The yields of propylene glycol monopalmitate, monostearate and monooleate with 50 mM triglycerides as acyl donors were 87.4, 65.1 and 83.2 mM, respectively.  相似文献   

6.
Rhamnolipids are becoming an important class of glycolipid biosurfactants. Herein, we describe for the first time the enzymatic synthesis of rhamnose fatty acid esters by the transesterification of rhamnose with fatty acid vinyl esters, using lipase from Pseudomonas stutzeri as a biocatalyst. The use of this lipase allows excellent catalytic activity in the synthesis of 4-O-acylrhamnose (99% conversion and full regioselectivity) after 3 h of reaction using tetrahydrofuran (THF) as the reaction media and an excess of vinyl laurate as the acyl donor. The role of reaction conditions, such as temperature, the substrates molar ratio, organic reaction medium and acyl donor chain-length, was studied. Optimum conditions were found using 35 °C, a molar ratio of 1:3 (rhamnose:acyldonor), solvents with a low logP value, and fatty acids with chain lengths from C4 to C18 as acyl donors. In hydrophilic solvents such as THF and acetone, conversions of up to 99–92% were achieved after 3 h of reaction. In a more sustainable solvent such as 2-methyl-THF (2-MeTHF), high conversions were also obtained (86%). Short and medium chain acyl donors (C4–C10) allowed maximum conversions after 3 h, and long chain acyl donors (C12–C18) required longer reactions (5 h) to get 99% conversions. Furthermore, scaled up reactions are feasible without losing catalytic action and regioselectivity. In order to explain enzyme regioselectivity and its ability to accommodate ester chains of different lengths, homology modelling, docking studies and molecular dynamic simulations were performed to explain the behaviour observed.  相似文献   

7.
Antioxidant properties of mono‐ and dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially tocopherol‐stripped sunflower oil (total tocopherols 8.7 mg/kg) and distilled fatty acid methyl esters (FAME) as a tocopherol‐free medium. The chemical reaction of tocopherols with diazomethane tested for the purpose to eliminate their antioxidant activity failed due to the negligible degree of methylation of hydroxyl group in the tocopherol molecule. Caffeic acid and protocatechuic acid (3,4‐dihydroxyphenolic acids) and their alkyl esters were found to be more active antioxidants than monohydroxyphenolic acid (p‐hydroxybenzoic acid), 2,5‐dihydroxyphenolic acid (gentisic acid), 3‐methoxy‐4‐hydroxyphenolic acids (vanillic and ferulic acids) and their corresponding alkyl esters. Naturally present tocopherols in refined sunflower oil proved to have a synergistic effect on gentisic acid but not on its alkyl esters. In contrast, tocopherols showed an antagonistic effect on alkyl esters of caffeic acid, because their protection factors decreased with increasing level of tocopherols in the test medium. Moreover, the antioxidant activity of these alkyl esters decreased with increasing length of their alkyl chain in conformity with the polar paradox hypothesis. Practical applications: Tocopherols as naturally present antioxidants influence considerably the antioxidant activity of other antioxidants added to plant oils used as a test medium. Distilled fatty acid methyl esters prepared from refined sunflower oil may serve as an optimal tocopherol‐free test medium. Some alkyl esters of phenolic acids were evaluated to be applicable as natural more lipophilic antioxidants in comparison with phenolic acids.  相似文献   

8.
Sucrose‐based esters are nonionic biosurfactants, which can be synthesized from the enzyme‐catalyzed esterification/transesterification of sucrose. The multi‐hydroxyl groups of sucrose and the immiscibility of sucrose with the acyl donors are the main bottlenecks in obtaining highly regioselective sucrose‐based esters. In this mini‐review, the effects of reaction conditions such as biocatalysts, design of solvent systems used as reaction media, modification and denaturation of substrates, and coupling with external auxiliary physical fields such as microwave irradiation and ultrasonic waves on the yield of sucrose esters and regioselectivity of products are highlighted. The existing problems in the field of enzymatic synthesis of sucrose esters as well as its future perspectives were pointed out. Copyright © 2011 Society of Chemical Industry  相似文献   

9.
The combination of various functional groups, such as epoxy, acetoxy, methoxy, thiirane, and aziridine, on the fatty acyl chain of soy fatty acid alkyl esters have been synthesized and evaluated as plasticizers in poly(vinyl chloride) (PVC) applications. Numerous synthetic procedures, such as epoxidation, methoxylation, acetylation, thiiration, and aziridination, were used for synthesizing multifunctional soy fatty acid alkyl esters. Epoxidized soybean oil fatty acid alkyl ester served as the key intermediate for functionalization. Partial or complete ring opening of the epoxide by reacting with methanol and the subsequent etherification or acetylation of the hydroxyl function produced epoxy, alkoxy, and acetoxy derivatives. The nucleophilic substitution of epoxide with sulfur by reacting with ammonium thiocyanate produced thiirane and epoxy thiiranes. Although the aziridine derivatives were synthesized by reacting unsaturated fatty acid alkyl esters with chloramine‐T, the compounds were fully characterized and their physical and analytical properties were determined. The high viscosity and darker color of aziridine and thiirane derivatives limit their usefulness, whereas the physical properties of the other derivatives were acceptable. The plasticizer evaluation of methoxy and acetoxy soy fatty acid esters (methyl and n‐butyl) demonstrated good compatibility with PVC, high efficiency (Shore hardness), and gelling properties were comparable to commercial plasticizer, di‐isoonyl phthalate. The abundant availability and cost‐effectiveness of starting materials and the readily adoptable chemical processes make the fatty acid ester derivatives viable bioplasticizers to replace the fossil fuel‐derived phthalates. J. VINYL ADDIT. TECHNOL., 23:93–105, 2017. © 2015 Society of Plastics Engineers  相似文献   

10.
Chlorogenic acid is a dietary polyphenol with important bioactivities. However, its high hydrophilicity prevents its applications as an antioxidant for lipid protection in a complex matrix such as food. Grafting an aliphatic chain onto chlorogenic acid, so‐called lipophilisation, via lipase‐catalysed esterification represents an efficient means of increasing its lipophilicity. A series of alkyl esters with various chain lengths were produced and used to explore the structure‐antioxidant activity relationship of amphiphilic antioxidants. Data obtained from complex systems (oil‐in‐water emulsion and cell culture) concluded that short or medium chain lengths enhance the antioxidant activity while longer chains tend to decrease the antioxidant ability of chlorogenic acid. This phenomenon remains to be fully explained. Acyl esters, in which the carboxylic acid group remains free were also produced and were shown to be interesting antioxidant candidates as well as useful tools for the understanding of antioxidant activities.  相似文献   

11.
The C‐terminal activation of peptides as prerequisite for the formation or ligation of peptide fragments is often associated with the problem of epimerization. We report that ruthenium‐catalyzed alkyne addition with (+)‐2,3‐O‐isopropylidene‐2,3‐dihydroxy‐1,4‐bis(diphenylphosphino)butane as ligand allows the racemization‐free synthesis of peptide enol esters tolerating a wide range of functional groups. The transformation can be performed in a variety of different solvents addressing the solubility issues imposed by peptides with varying amino acid side chain patterns. We show that peptide enol esters with an amide motif in the enol moiety are excellent acyl donors for the peptide condensation with other peptide fragments in organic solvents using serine endopeptidase subtilisin A as catalyst. The reported combination of transition metal catalysis with enzymatic peptide ligations adds an important tool for the racemization‐free synthesis and ligation of peptides which is compatible even with unprotected amino acid side chains.  相似文献   

12.
The ability of immobilized lipases IM60 fromMucor miehei and SP435 fromCandida antarctica to modify the fatty acid composition of selected vegetable oils by incorporation of n−3 polyunsaturated fatty acids into the vegetable oils was studied. The transesterification was carried out in organic solvent with free acid and ethyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as acyl donors. With free EPA as acyl donor, IM60 gave higher incorporation of EPA than SP435. However, when ethyl esters of EPA and DHA were the acyl donors, SP435 gave higher incorporation of EPA and DHA than IM60. When IM60 and free acid were used, the addition of 5 μL water increased EPA incorporation into soybean oil by 4.9%. With ethyl ester of EPA as acyl donor, addition of 2 μL water increased EPA incorporation by 3.9%. For SP435, addition of water up to 2μL resulted in increased EPA incorporation, but the incorporation declined when the added water exceeded this amount. The addition of water increased the EPA incorporation into Trisun 90 after 24 h reaction but not the reaction rate at early stages of the reaction.  相似文献   

13.
In the quest to use antioxidant compounds occurring in nature or related compounds, extensive studies have been made on vegetable oils, animal fats, apocarotenal, and vitamin A as substrates with ascorbyl palmitate, tocopherols, and ascorbic acid as antioxidants. Antioxidant efficiency varies with the substrate. Ascorbyl palmitate at a level of 0.01% provides a useful increase in the shelf-life of vegetable oils. Alone it is better than butylated hydroxytoluene and butylated hydroxyanisole and in combinations with other known antioxidants improves the shelf-life of all vegetable oils, as well as potato chips. Solubility problems with ascorbyl palmitate and other esters of ascorbic acid are discussed. The tocopherols have their greatest effect in protection of animal fats, carotenoids, and vitamin A. Experiments utilizing tocopherols and tocopherol combinations are presented. The activity of ascorbic acid, an excellent scavenger of oxygen, is reviewed. Quenchers of singlet oxygen do not inhibit the direct oxidation of fats and oils under the conditions used.  相似文献   

14.
Furan fatty acids (F‐acids) are a class of natural antioxidants with a furan moiety in the acyl chain. These minor fatty acids have been reported to occur with high proportions in the cholesteryl ester fraction of fish livers. Here we present a method for the direct analysis of intact cholesteryl esters with F‐acids and other fatty acids in cod liver lipids. For this purpose, the cholesteryl ester fraction was isolated by solid phase extraction (SPE) and subsequently analyzed by gas chromatography with mass spectrometry (GC/MS) using a cool‐on‐column inlet. Pentadecanoic acid esterified with cholesterol was used as an internal standard. GC/MS spectra of F‐acid cholesteryl esters featured the molecular ion along with characteristic fragment ions for both the cholesterol and the F‐acid moiety. All investigated cod liver samples (n = 8) showed cholesteryl esters of F‐acids and, to a lower degree, of conventional fatty acids. By means of GC/MS‐SIM up to ten F‐acid cholesteryl esters could be determined in the samples. The concentrations of cholesteryl esters with conventional fatty acids amounted to 78–140 mg/100 g lipids (mean 97 mg/100 g lipids), while F‐acid cholesteryl esters were present at 47–270 mg/100 g lipids (mean 130 mg/100 g lipids).  相似文献   

15.
Tsujita T  Sumiyoshi M  Okuda H 《Lipids》1999,34(11):1159-1166
The synthesis/hydrolysis of wax esters was studied in an aqueous solution using purified rat pancreatic lipase, porcine pancreatic carboxylester lipase, and Pseudomonas fluorescens lipase. The equilibrium between wax ester synthesis and hydrolysis favored ester formation at neutral pH. The synthesizing activities were measured using free fatty acid or triacylglycerol as the acyl donor and an equimolar amount of long-chain alcohol as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with these lipases, was ester was synthesized, in a dose- and time-dependent manner, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was about 0.9/0.1. These lipases catalyzed the hydrolysis of palmityl oleate emulsified with gum arabic, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was also about 0.9/0.1. The apparent equilibrium ratio of wax ester/free fatty acid catalyzed by lipase depended on incubation pH and fatty alcohol chain length. When equimolar amounts of trioleoylglycerol and fatty acyl alcohol were incubated with pancreatic lipase, carboxylester lipase, or P. fluorescens lipase, wax esters were synthesized dose-dependently. These results suggest that lipases can catalyze the synthesis of wax esters from free fatty acids or through degradation of triacylglycerol in an aqueous medium.  相似文献   

16.
Lipase-catalyzed synthesis of sugar fatty acid esters was performed in a heterogeneous reaction system in the presence of an organic solvent serving as adjuvant. Although the sugar is almost insoluble in such a system, high conversions to the corresponding sugar esters were achieved, due to crystallization of the product. Acylation occurred regioselectively at the primary hydroxyl group and subsequent diacylation was observed only in the case of caprylic acid (2–5%). Best conditions were found for solvents having low log P values and low product solubility such as acetone, using immobilized lipase from Candida antarctica (CAL-B, Novo SP435) and fatty acids with chain lengths from C12 to C8 as acyl donors. The esterification of β-D(+)-glucose with stearic acid resulted in up to 100% conversion after 48 hours equal to a productivity of 0.4 mmol sugar ester per gram lipase and hour.  相似文献   

17.
Certain N-acylethanolamines interact with cannabinoid receptors and have anorexic and neuroprotective effects. Traditional methods for the synthesis of N-acylethanolamines use fatty acid chlorides, fatty acid methyl esters, free fatty acids and triacylglycerols as acyl donors to react with ethanolamine. In the present study, we investigated the feasibility of using fatty acid vinyl esters as the acyl donor to synthesize N-stearoyl and N-palmitoylethanolamine. Theoretically, the use of fatty acid vinyl esters should lead to an irreversible reaction because the volatile acetaldehyde by-product is easily removed. Four reaction conditions, i.e. catalyst concentration, substrate ratio, temperature, and time were evaluated. The reaction performed at mild temperatures and with an excess amount of ethanolamine which acted as both reactant and solvent resulted in the formation of high purity N-stearoyl and N-palmitoylethanolamine. When 20 mmol ethanolamine was reacted with 1 mmol vinyl stearate at 80 °C for 1 h with 1% sodium methoxide as catalyst, N-stearoylethanolamine with 96% purity was obtained after the removal of excess ethanolamine without further purification, while N-palmitoylethanolamine with 98% purity was obtained by reacting with the same substrate ratio at 60 °C for 1.5 h with 3% catalyst. Complete conversion of vinyl stearate and palmitate was achieved.  相似文献   

18.
A study was made with sheep on the formation in vitro of long chain fatty acid esters of cholesterol by the lecithin-cholesterol-acyltransferase system present in the plasma and the acyl CoA-cholesterol-acyltransferase system present in the liver. The rate of cholesterol esterification in the plasma was 0.024 μmoles/ml/hr. The relative pattern of fatty acids esterified during incubation of the plasma remained constant over the 8 hr period of incubation and was similar to the fatty acids in the plasma cholesteryl esters before incubation began and to the fatty acids in the 2-position of the plasma lecithin. The predominant cholesteryl esters synthesized contained monoenoic and dienoic fatty acids. Unlike the bovine, there was no apparent discrimination in favor of the 18∶2 containing species of plasma lecithin as donors of fatty acids. This difference could be accounted for by the similarity in the 18∶2 content of the phospholipids present in the high density (density >1.062 and < 1.21) and the low density (density > 1.006 and <1.063) lipoprotein fractions of the sheep plasma. The possibility of some discrimination against 20∶4 during cholesterol ester synthesis in the plasma of the sheep cannot be excluded. In the liver, the predominant cholesteryl esters synthesized contained saturated and monoenoic fatty acids; cholesteryl linoleate was synthesized to a very much less extent. There was considerable similarity between the composition of the unesterified fatty acid fraction of the liver before incubation began and the fatty acid composition of the cholesteryl esters synthesized during incubation. Addition of sonicated suspensions of free fatty acids altered markedly the fatty acid pattern of the cholesteryl esters synthesized by the liver slices. From the evidence presented it is concluded that the cholesteryl esters in sheep plasma are syntheized mainly by the plasma lecithin-cholesterol-acyltransferase system. The results are discussed in relation to cholesterol esterification systems demonstrated in the plasma and liver of monogastric animals.  相似文献   

19.
Regioisomerically pure 1(3)-rac-monoacylglycerols are conveniently prepared in high yields (>75%) and in multigram quantities by enzymatic esterification of glycerol in the presence of various lipases(Chromobacterium viscosum, Rhizopus delemar, Rhizomucor miehei) with a variety of different acyl donors, such as free fatty acids, fatty acid alkyl esters, vinyl esters and triacylglycerols, as well as natural fats and oils. All reactions are carried out in aprotic organic solvents with low water content, namelyn-hexane, diethyl ether, tBuOMe or mixtures of these solvents. Essential for the success of these transformations were the following two factors. First, the creation of an artificial interphase between the solvent-immiscible hydrophilic glycerol and the hydrophobic reaction medium by its adsorption onto a solid support. Second, a facile system for the separation of the desired monoacylglycerol from the reaction mixture, coupled with the continuous recycling of acyl donor and undesirable by-products.  相似文献   

20.
The total oil production capacity of isano oil is estimated at about 10,000 tons annually. Previous studies of this oil revealed that it is rich in fatty acids including a conjugated diyne moiety. This makes isano oil an excellent candidate for sustainable applications development. However, only a few of its fatty acids have been isolated and identified so far. In this study, we have reinvestigated this oil by characterizing its physicochemical properties and isolating several of its fatty acids as ethyl esters for their detailed structural analysis and identification. Six ethyl esters of fatty acids constituting isanic oil were isolated by flash column chromatography and semipreparative HPLC. The detailed structural analysis of these fatty acid esters by infrared, high resolution, mass spectroscopy, and nuclear magnetic resonance (1‐D and 2‐D) allowed determining unequivocally their chemical structure. The main fatty acid component of the oil (35.7 %) was identified as isanic acid. Four minor acids were found to possess also two conjugated triple bonds, while the sixth fatty acid does not contain carbon–carbon triple bonds nor double bonds but possessed a cis epoxide function. Results obtained in this study are currently being used to explore potential applications of isano oil.  相似文献   

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