- 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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- Preparation of Triacylglycerol Molecular Species by Interesterification Using Endocellular Lipase in n-Hexane
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The interesterification of triacylglycerol with fatty acid was done to prepare triacylglycerol molecular species.Optimum operating conditions for the interesterification using a 1,3-positional specific endocellular lipase from Rhizopus japonicus NR400 in a batch system were investigated.The reaction was done at 40 deg C for 5 hr in the following system: Trioleoylglycerol palmitic acid = 1:3.5 (mol/mol), 10 ml n-hexane/g trioleoylglycerol, and 2500 units of enzyme/g trioleoylglycerol.Under these conditions, the content of palmitoyl groups in 1,3-positions of triacylglycerol was about 60 molpercent.Additional interesterification (2-cycle reaction) using palmitic acid and the novel triacylglycerol prepared by one-step interesterification (1-cycle reaction) resulted in a preparation of highly pure 1,3-dipalmitoyl-2-oleoylglycerol.
- Kimura, Masami,Hasegawa, Kiyozo,Takamura, Hitoshi,Matoba, Teruyoshi
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p. 3039 - 3044
(2007/10/02)
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- Synthesis of Triglycerides from 1,3-Dibromopropan-2-ol
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1,3-Dibromopropan-2-ol (I) was converted into an acyl derivative (VI) by reaction with an appropriate acyl chloride in the presence of pyridine.The acyl derivative (VI) was subjected to nucleophilic substitution with 3 mol. equiv. tris(decyl)methylammonium carboxylate in refluxing hexane.This led to symmetrical diacid triglycerides in 90-94percent yield.Substitution with an equimolar amount of the carboxylate afforded, predominantly, the 1,2-bisacyloxy-3-bromopropane (VII) which could be easily isolated and further substituted to give unsymmetrical diacid- and triacid-triglycerides in ca. 96percent yield.Lipolysis showed the synthetic triglycerides to be ca. 99percent pure.
- Bhati, Asharam,Hamilton, Richard J.,Steven, David A.,Aneja, Rajender,Padley, Frederick B.
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p. 1553 - 1558
(2007/10/02)
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