Synthesis and nuclear magnetic resonance properties of all geometrical isomers of conjugated linoleic acids

Jie, Marcel S. F. Lie Ken; Pasha, Mohammed Khysar; Alam, Mohammad Shahidul

doi:10.1007/s11745-997-0134-9

Cited by 56 publications

(43 citation statements)

References 14 publications

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“…9-cis,11-trans CLA methyl ester was purchased from Matreya Inc. (Pleasant Gap, PA). The presence of only one CLA methyl ester isomer was confirmed by 13 C NMR (7). α-Tocopherol was obtained from Merck (Darmstadt, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…Thus, addition of oxygen to the pentadienyl radical 2, which is the same radical as the one formed from methyl 9-cis,12-translinoleate, leads to the preferential formation of the 13-peroxyl radical 6 having a cis,trans geometry over the 9-peroxyl radical 4, which has the more stable trans,trans configuration. When the oxidation occurs in the presence of the good hydrogen atom donor, α-tocopherol, the next step is relatively fast and selectively produces 13-OOH-9c,11t (7). Smaller amounts of the other three primary or kinetic hydroperoxides, 5, 12, and 14, are also expected to form.…”

Section: Table 1 Fragment Ions From Trimethylsilyl Ethers Of Stearic mentioning

confidence: 99%

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Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Hämäläinen

Sundberg

Hase

et al. 2002

Lipids

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The initial steps in the autoxidation of CLA methyl ester are poorly understood. The aim of this study was to determine the stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of a good hydrogen atom donor. For this purpose, 9-cis,11-trans CLA methyl ester was autoxidized in the presence of alpha-tocopherol under atmospheric oxygen at 40 degrees C in the dark. The CLA methyl ester hydroperoxides were isolated, reduced to the corresponding hydroxy derivatives, and separated by HPLC. The stereochemistry of seven hydroxy-CLA methyl esters was investigated. The position of the hydroxy group was determined by GC-MS. The geometry as well as the position of the double bonds in the alkyl chain was determined by NMR. In addition, the 13C NMR spectra of six hydroxy-CLA methyl esters were assigned using COSY, gradient heteronuclear multiple bond correlation, gradient heteronuclear single quantum correlation, and total correlation spectroscopy experiments. The autoxidation of 9-cis,11-trans CLA methyl ester in the presence of a good hydrogen atom donor is stereoselective in favor of one geometric isomer, namely the 13-(R,S)-hydroperoxy-9-cis,11-trans-octadecadienoic acid methyl ester. Three types of conjugated diene hydroperoxides are formed as primary hydroperoxides: trans,trans hydroperoxides (12-OOH-8t,10t and 9-OOH-10t,12t), a cis,trans hydroperoxide with the trans double bond adjacent to the hydroperoxide-bearing carbon atom (13-OOH-9c,11t), and a new type of cis,trans lipid hydroperoxide with the cis double bond adjacent to the hydroperoxide-bearing carbon atom (8-OOH-9c,11t). In addition, three nonkinetic hydroperoxides (13-OOH-9t,11t, 8-OOH-9t,11t, and 9-OOH-10t,12c) are formed. This study supports the theory that CLA methyl ester autoxidizes at least partly through an autocatalytic free radical reaction. The complexity of the hydroperoxide mixture is due to formation of two different pentadienyl radicals. Moreover, the stereoselectivity in favor of one geometric isomer can be explained by the selectivity of the two previous steps: the preferential formation of a W-conformer of the pentadienyl radical over the Z-conformer, and regioselectivity of the oxygen addition to the pentadienyl radical.

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Section: Methodsmentioning

confidence: 99%

Section: Table 1 Fragment Ions From Trimethylsilyl Ethers Of Stearic mentioning

confidence: 99%

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Hämäläinen

Sundberg

Hase

et al. 2002

Lipids

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“…Conjugated linoleic acid (CLA) is a term used to describe a mixture of positional and geometric isomers of linoleic acid (1,2). Dietary CLA has been shown to inhibit tumorigenesis in a number of animal models, which is in distinct contrast to the effects of the parent compound linoleic acid (3)(4)(5)(6)(7)(8).…”

mentioning

confidence: 99%

Modulation of prostaglandin H synthase activity by conjugated linoleic acid (CLA) and specific CLA isomers

Bulgarella

Patton

Bull

2001

Lipids

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Conjugated linoleic acid (CLA) has been shown to inhibit tumorigenesis in animal models and is cytostatic to numerous cell lines in vitro. However, the mechanism of action is unknown. In the current study, we determined the effects of CLA and specific isomers of CLA on the rate of oxygenation of arachidonic acid by prostaglandin H synthase (PGHS) in ram seminal vesicle microsomes. The enzyme was incubated with 0.1 to 100 microM CLA or specific isomers of CLA for 2 min prior to the addition of 44 to 176 microM arachidonate. The isomers tested were 9(E),11(E) CLA; 9(Z),11(E) CLA; 9(Z),11(Z) CLA, and 10(E),12(2) CLA. For a positive inhibitor control, flurbiprofen was used at 0.75 to 2.50 microM. Enzyme activity was assessed by measuring the rate of oxygen consumption. Inclusion of CLA or specific isomers of CLA in the incubation mixtures inhibits PGHS. The efficacy differs for each isomer, with the 9(Z),11 (E) CLA isomer being the most effective and the 9(Z),11 (Z) CLA isomer being the least effective inhibitor among the four CLA isomers tested. The Ki values obtained by Dixon replots range from 18.7 microM for the most effective isomer, 9(Z),11 (E) CLA, to 105.3 microM for the least effective isomer, 9(2),11(2) CLA. The Ki value for flurbiprofen with ram seminal vesicle microsomes was 0.33 microM. As the concentration of arachidonate was increased, the CLA-dependent inhibition of PGHS decreased, suggesting competitive inhibition. The results of this study demonstrate the potential of CLA and specific isomers of CLA to modulate prostaglandin biosynthesis.

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“…The study was conducted on a synthetic sample of C18:2(9Z,11E), which was prepared from ricinoleic acid (castor oil, Ricinus cummunis) as outlined in Fig. 1 [14].…”

Section: Introductionmentioning

confidence: 99%

Epoxidation of a conjugated linoleic acid isomer

Jie

Lam

et al. 2003

Euro J Lipid Sci & Tech

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Epoxidation of a conjugated linoleic acid isomerEpoxidation of methyl (9Z,11E)-octadecadienoate (1) with various epoxidizing agents viz. m-chloroperoxybenzoic acid, dimethyl dioxirane, methyltrioxorhenium/hydrogen peroxide, potassium peroxomonosulfate (Oxone, 2KHSO 5 · KHSO 4 · K 2 SO 4 )/tetrahydrothiopyran-4-one, and Novozyme 435/hydrogen peroxide is described. The reactions furnished the corresponding mono-epoxy [methyl (11,12E)-epoxy-(9Z)-octadecenoate (2) and methyl (9,10Z)-epoxy-(11E)-octadecenoate (3)] and a mixture of diastereomers of syn-and anti-diepoxy-stearate [methyl (9,10Z;11,12E)-diepoxystearate (4a-4d)], which were identified by a combination of spectroscopic and spectrometric analyses.

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Synthesis and nuclear magnetic resonance properties of all geometrical isomers of conjugated linoleic acids

Cited by 56 publications

References 14 publications

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Modulation of prostaglandin H synthase activity by conjugated linoleic acid (CLA) and specific CLA isomers

Epoxidation of a conjugated linoleic acid isomer

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