Physical Properties of Two Isomers of Conjugated Linoleic Acid

Uehara, Hidetaka; Suganuma, Tomomi; Negishi, Satoshi; Uda, Yukihiro; Furukawa, Yoshinori; Ueno, Satoru; Sato, Kiyotaka

doi:10.1007/s11746-007-1164-z

Cited by 13 publications

(11 citation statements)

References 23 publications

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“…The two natural CLA-containing PCs differed in their effects, with the c9t11 CLA-PC showing a more ‘fluidizing’ effect than the t10c12 isomer. This is consistent with previous studies on free CLA, which showed that c9t11 CLA had lower Tm than that of t10c12 CLA [29]. The double cis CLA-PC showed the maximum decrease in T m , while the double trans CLA-PC isomer showed the smallest change.…”

Section: Resultssupporting

confidence: 92%

Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes

Subbaiah

Sircar

Aizezi

et al. 2010

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Conjugated linoleic acids (CLA) are known to exert several isomer-specific biological effects, but their mechanisms of action are unclear. In order to determine whether the physicochemical effects of CLA on membranes play a role in their isomer-specific effects, we synthesized phosphatidylcholines (PCs) with 16:0 at sn-1 position and one of four CLA isomers (trans10 cis12 (A), trans9 trans11 (B), cis9 trans11 (C), and cis9 cis11 (D)) at sn-2, and determined their biophysical properties in monolayers and bilayers. The surface areas of the PCs with the two natural CLA (A and C) were similar at all pressures, but they differed significantly in presence of cholesterol, with PC-A condensing more than PC-C. Liposomes of PC-A similarly showed increased binding of cholesterol compared to PC-C liposomes. PC-A liposomes were less permeable to carboxyfluorescein compared to PC-C liposomes. The PC with two trans double bonds (B) showed the highest affinity to cholesterol and lowest permeability. The two natural CLA PCs (A and C) stimulated lecithin-cholesterol acyltransferase activity by 2-fold, whereas the unnatural CLA PCs (B and D) were inhibitory. These results suggest that the differences in the biophysical properties of CLA isomers A and C may partly contribute to the known differences in their biological effects.

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Section: Resultssupporting

confidence: 92%

Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes

Subbaiah

Sircar

Aizezi

et al. 2010

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…As t10,c12 CLA was incorporated into the cell membrane to a greater extent than c9,t11 CLA (33% vs. 22%, respectively) in the present study, this suggests that the membrane might be more disrupted by t10,c12 CLA treatment. In support of this, recently, it was demonstrated that the physical properties of these two isomers are quite different [41]. The greater incorporation of t10,c12 CLA was at the expense of SFA as compared to the LA-and c9,t11 CLA-treated groups.…”

Section: Discussionmentioning

confidence: 90%

Conjugated Linoleic Acid Decreases MCF‐7 Human Breast Cancer Cell Growth and Insulin‐Like Growth Factor‐1 Receptor Levels

Amarù

Field

2009

Lipids

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In vitro work suggests that conjugated linoleic acid (CLA) isomers (c9,t11 and t10,c12) are cytotoxic to human breast cancer cells, however the mechanism remains unknown. Using human MCF-7 breast cancer cells, we examined the effects of c9,t11 and t10,c12 CLA compared to oleic acid (OA), linoleic acid (LA), or untreated cells on cell membrane phospholipid composition, cell survival, and the insulin-like growth factor-I (IGF-I) and the downstream insulin receptor substrate-1 (IRS-1). Both CLA isomers were incorporated into membrane phospholipids (p < 0.05). Compared to untreated cells, c9,t11 or t10,c12 CLA significantly reduced the metabolic activity of IGF-I stimulated MCF-7 cells, increased lactate dehydrogenase (LDH) release, and decreased cellular concentrations of the IGF-I receptor (IGF-IR) and insulin receptor substrate-1 (p < 0.05). Incubation with t10,c12 CLA also reduced the levels of phosphorylated IGF-1R. The effects on all of these measures were greater (p < 0.05) for t10,c12 CLA compared to c9,t11 CLA. There were few differences between LA-treated and c9,t11 CLA-treated cells, whereas cellular metabolic activity, LDH release, and IGF-IR concentrations differed between t10,c12 CLA-treated and LA-treated cells (p < 0.05). OA stimulated growth compared to the untreated condition (p < 0.05). In summary, this study demonstrated that the t10,c12 CLA isomer inhibits growth of MCF-7 cells and suggested that this may be mediated through incorporation into cellular phospholipids and interference with the function of IGF-I and related signaling proteins.

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“…In addition to the monolayer isotherm data discussed earlier (37), thermal properties of the two isomers are also similar. (50) the melting temperature of C9T11 is 14.9 °C and the enthalpy of fusion is 38.7 kJ/mol. For T10C12, the melting temperature of C9T11 is 19.8 °C and the enthalpy of fusion is 35.6kJ/mol.…”

Section: Discussionmentioning

confidence: 96%

“…For T10C12, the melting temperature of C9T11 is 19.8 °C and the enthalpy of fusion is 35.6kJ/mol. (50) In this paper we have used MD simulations to examine atomic level differences in structure and interactions in CLA bilayers composed of the two isomers C9T11 and T10C12. In our CLA simulations, we have found that the different degrees of chain segmental ordering in the two isomers does not appear to significantly affect certain large scale bilayer structural properties.…”

Section: Discussionmentioning

confidence: 99%

Conjugated double bonds in lipid bilayers: A molecular dynamics simulation study

Zhao

Subbaiah

Chiu

et al. 2011

Chemistry and Physics of Lipids

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Conjugated linoleic acids (CLA) are found naturally in dairy products. Two isomers of CLA, that differ only in the location of cis and trans double bonds, are found to have distinct and different biological effects. The cis 9 trans 11 (C9T11) isomer is attributed to have the anti-carcinogenic effects, while the trans 10 cis 12 (T10C12) isomer is believed to be responsible for the anti-obesity effects. Since dietary CLA are incorporated into membrane phospholipids, we have used Molecular Dynamics (MD) simulations to investigate the comparative effects of the two isomers on lipid bilayer structure. Specifically, simulations of phosphatidylcholine lipid bilayers in which the sn-2 chains contained one of the two isomers of CLA were performed. Force field parameters for the torsional potential of double bonds were obtained from ab initio calculations. From the MD trajectories we calculated and compared structural properties of the two lipid bilayers, including areas per molecule, density profiles, thickness of bilayers, tilt angle of tail chains, order parameters profiles, radial distribution function (RDF) and lateral pressure profiles. The main differences found between bilayers of the two CLA isomers, are (1) the order parameter profile for C9T11 has a dip in the middle of sn-2 chain while the profile for T10C12 has a deeper dip close to terminal of sn-2 chain, and (2) the lateral pressure profiles show differences between the two isomers. Our simulation results reveal localized physical structural differences between bilayers of the two CLA isomers that may contribute to different biological effects through differential interactions with membrane proteins or cholesterol.

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Physical Properties of Two Isomers of Conjugated Linoleic Acid

Cited by 13 publications

References 23 publications

Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes

Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes

Conjugated Linoleic Acid Decreases MCF‐7 Human Breast Cancer Cell Growth and Insulin‐Like Growth Factor‐1 Receptor Levels

Conjugated double bonds in lipid bilayers: A molecular dynamics simulation study

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