- Enantioselective chromatography in analysis of triacylglycerols common in edible fats and oils
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Enantiomers of racemic triacylglycerol (TAG) mixtures were separated using two chiral HPLC columns with a sample recycling system and a UV detector. A closed system without sample derivatisation enabled separation and identification by using enantiopure reference compounds of eleven racemic TAGs with C12-C22 fatty acids with 0-2 double bonds. The prolonged separation time was compensated for byfewer pretreatment steps. Presence of one saturated and one unsaturated fatty acid in the asymmetricTAG favoured the separation. Enantiomeric resolution, at the same time with stronger retention of TAGs,increased with increasing fatty acid chain length in the sn-1(3) position. Triunsaturated TAGs containingoleic, linoleic or palmitoleic acids did not separate. The elution order of enantiomers was determined bychemoenzymatically synthesised enantiopure TAGs with a co-injection method. The method is applicableto many natural fats and oils of low unsaturation level assisting advanced investigation of lipid synthesisand metabolism.
- Kalpio, Marika,Nylund, Matts,Linderborg, Kaisa M.,Yang, Baoru,Kristinsson, Bj?rn,Haraldsson, Gudmundur G.,Kallio, Heikki
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p. 718 - 724
(2015/02/02)
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- Synthesis of enantiopure structured triacylglycerols
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The synthesis of nine enantiopure structured triacylglycerols (TAGs) of the AAB type is described, all possessing the (S)-absolute configuration. Six of them possess one saturated and two identical unsaturated fatty acyl chains, whereas the remaining three possess two identical saturated fatty acids along with one unsaturated fatty acid. The former group was synthesized by a five-step chemoenzymatic route involving a highly regioselective immobilized Candida antarctica lipase, starting from enantiopure (R)-solketal. The second group was prepared by a fully chemical five-step approach based on the same chiral precursor. Such enantiopure TAGs are strongly required as standards for the enantiospecific analysis of intact TAGs in fats and oils.
- Kristinsson, Bjoern,Linderborg, Kaisa M.,Kallio, Heikki,Haraldsson, Gudmundur G.
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p. 125 - 132
(2014/02/14)
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- Regioisomeric characterization of triacylglycerols using silver-ion HPLC/MS and randomization synthesis of standards
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Silver-ion normal-phase high-performance liquid chromatography (HPLC) provides a superior separation selectivity for lipids differing in the number and position of double bonds in fatty acid chains including the resolution of triacylglycerol (TG) regioiso
- Lisa, Miroslav,Velinska, Hana,Holcapek, Michal
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experimental part
p. 3903 - 3910
(2010/03/23)
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- Synthesis and physical properties of symmetrical and non-symmetrical triacylglycerols containing two palmitic fatty acids
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A series of symmetrical (ABA) and non-symmetrical (AAB) triacylglycerol (TAG) isomers containing "A," palmitic (P; 16:0) acid, and "B," either oleic (O; 9c-18:1), elaidic (E; 9t-18:1), linoleic (L; 9c,12c-18:2) or linolenic (Ln; 9c,12c,15c-18:3) fatty acids were synthesized by esterification of the thermodynamically more-stable 1,3-di- or 1(3)-monoacylglycerols [1,3-DAG or 1(3)-MAG], respectively. 1,3- dipalmitoylglycerol (1,3P-DAG) was esterified with O, L or Ln acid to prepare the symmetrical TAG isomers POP, PLP and PLnP, while the O- E-, L- and Ln-1(3)MAG precursors, synthesized or obtained commercially, were esterified with P acid to prepare the non-symmetrical TAG isomers OPP, EPP, LPP and LnPP, respectively. The drop point(s), solid fat content and melting point values of the synthesized TAG were determined. The 1,3-dipalmitoylglycerol (1,3P-DAG) and 1(3)P-MAG precursors were prepared, in multi-gram quantities, by partial glycerolysis (glycerol/p-toluenesulfonic acid) of tripalmitin. After fractionation by silica gel chromatography, the 1(3)P-MAG and 1,3P-DAG isomers (ca. 80% of total MAG or DAG) were purified (>98%) by crystallization from acetone [silver ion-HPLC was utilized to determine the structural purities of the DAG (or MAG) precursors, and the synthesized TAG]. Esterification of the appropriate, thermodynamically more-stable MAG or DAG precursors was found to be a very versatile method for synthesis (in 80-90% yields) of multi-gram (3-5 g) quantities of symmetrical and non-symmetrical TAG isomers, in chemical and structural purities of >96 and 97-99%, respectively.
- Adlof,List
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- Regioselective and stereospecific acylation across oxirane- and silyloxy systems as a novel strategy to the synthesis of enantiomerically pure mono-, di- and triglycerides
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A trifluoroacetate-catalyzed opening of the oxirane ring of glycidyl derivatives bearing allylic acyl or alkyl functionalities with trifluoroacetic anhydride (TFAA), provides an efficient entry to configurationally homogeneous 1(3)-acyl- or 1(3)-O-alkyl-sn-glycerols. Selective introduction of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl- (TIPS) transient protections at the terminal sites within these key intermediates secures 1(3)-acyl- or 1(3)-O-alkyl-3(1)-O-TBDMS (or TIPS)-sn-glycerols as general bifunctional precursors to 1,2(2,3)-diacyl-, 1(3)-O-alkyl-2-acyl- and 1,3-diacyl-sn-glycerols and hence triester isosters. Incorporation of a requisite acyl residue at the central carbon of the silylated synthons with a subsequent Et3N·3HF-promoted, direct trichloroacetylation across the siloxy system by trichloroacetic anhydride (TCAA), followed by cleavage of the trichloroacetyl group, affords the respective 1,2(2,3)-diacyl- or 1(3)-O-alkyl-2-acyl-sn-glycerols. Alternatively, a reaction sequence involving: (i) attachment of a trichloroacetyl fragment at the stereogenic C2-centre of the monosilylated glycerides; (ii) replacement of the silyl moiety by a short- or long-chain carboxylic acid residue by means of the acylating agent: tetra-n-butylammonium bromide (TBABr)-carboxylic acid anhydride (CAA)-trimethylsilyl bromide (TMSBr); and (iii) removal of the trichloroacetyl replacement, provides pure 1,3-diacyl-sn-glycerols. The TBABr-CAA-TMSBr reagent system allows also a one-step conversion of 1,2-diacylglycerol silyl ethers into homochiral triglycerides with predefined asymmetry and degree of unsaturation. These compounds can also be accessed via a two-step one-pot approach where the trichloroacetyl derivatives of 1,2(2,3)- or 1,3-diacyl-sn-glycerols serve as triester building blocks for establishing the third ester bond at preselected C3(1)- or C2-positions within the glycerol skeleton at the very last synthetic stage. In all instances, the target compounds were produced under mild conditions, in high enantiomeric purity, and in practically quantitative yields. The Royal Society of Chemistry 2007.
- Stamatov, Stephan D.,Stawinski, Jacek
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p. 3787 - 3800
(2008/10/09)
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- Synthesis of the structured lipid 1,3-dioleoyl-2-palmitoylglycerol from palm oil
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Human milk fat contains 20-25% palmitic acid (16:0) and 30-35% oleic acid (18:1). More than 60% of the palmitic acid occurs at the sn-2 position of the glycerol backbone. Palm oil is a rich source of both palmitic and oleic acids. The structured lipid 1,3-dioleoyl-2-palmitoylglycerol (OPO) is an important ingredient in infant formula. OPO was synthesized from palm oil by a three-step method. In the first step, low-temperature fractionation was applied to palm oil FA, yielding a palmitic acid-rich fraction (87.8%) and an oleic acid-rich fraction (96%). The palmitic acid content was further increased to 98.3% by transforming palmitic acid into ethyl palmitate. In the second step, esterificalion of ethyl palmitate and glycerol catalyzed by lipase Novozym 435 under vacuum (40 mm Hg) was employed for the synthesis of tripalmitin. Finally, OPO was obtained by the reaction of tripalmitin with oleic acid catalyzed by Lipase IM 60. In this final step, the TAG content in the product acylglycerol mixture was 97%, and 66.1 % oleic acid was incorporated into TAG. Analysis of the FA composition at the sn-2 position of TAG showed 90.7 mol% of palmitic acid and 9.3 mol% of oleic acid. OPO content in the product TAG was ca. 74 mol%. Thus, an efficient method was developed for the synthesis of OPO from palm oil.
- Chen, Ming-Lung,Vali, Shaik Ramjan,Lin, Jih-Yao,Ju, Yi-Hsu
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p. 525 - 532
(2007/10/03)
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- Host-recognizing kairomones for parasitic wasp, Anisopteromalus calandrae, from larvae of azuki bean weevil, Callosobruchus chinensis.
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Host-recognizing kairomones for the stinging behavior of the parasitic wasp, Anisopteromalus calandrae, were identified on host azuki bean weevil larvae, Callosobruchus chinensis (L.). The kairomones were extracted with acetone from Chinese green beans, from which emerged wasps and host weevils had been removed. The kairomones are a mixture of triacylglycerols and fatty acids, each of which is separately active, and with no observable synergistic effect between them. These compounds are known to be constituents of an oviposition-marking pheromone of host azuki bean weevils. However, they differ from the previously reported saturated hydrocarbons and diacylglycerols of the kairomone that another parasitic wasp, Dinarmus basalis, uses for the host recognition of C. chinensis. Thus, A. calandrae and D. basalis selectively utilize different constituents of the oviposition-marking pheromone of C. chinensis as host-recognizing kairomones.
- Onodera, Junko,Matsuyama, Shigeru,Suzuki, Takahisa,Fujii, Koichi
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p. 1209 - 1220
(2007/10/03)
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- Synthesis and physicochemical characterization of mixed diacid triglycerides that contain elaidic acid
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The synthesis of symmetrical and asymmetrical palmito- and stearo-elaidic triglycerides (PEP, SES, EPP, PEE, ESS, and SEE, in which P = palmitic, S = stearic, and E = elaidic acid) was undertaken to investigate their polymorphism. The chemical pathways and the purification steps, including crystallization and adsorption chromatography, are described. The different chromatographic analyses (gas-liquid chromatography: carbon number profile and fatty acid methyl ester profile, and high-performance liquid chromatography) revealed that the purity of the synthesized products was superior to 99% except for SES (>96%). The thermal behavior, as well as the polymorphism of these triglycerides, has been investigated by means of differential scanning calorimetry and powder X-ray diffraction spectroscopy at variable temperatures. The six compounds crystallize according to a double chainlength packing. The most stable polymorphic form of palmito-elaidic triglycerides belongs to the β′ variety, whereas the stearo-elaidic triglycerides are β stable.
- Elisabettini,Lognay,Desmedt,Culot,Istasse,Deffense,Durant
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p. 285 - 291
(2007/10/03)
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