Effects of Conjugated Linoleic Acid (CLA) Isomers on Oxygen Diffusion−Concentration Products in Liposomes and Phospholipid Solutions

Abstract

Conjugated linoleic acids (CLAs) are a group of octadecadienoic acids (18:2) that are naturally present in food products and may have beneficial health effects. Liposomes and ethanol solutions were prepared by mixing synthetic phosphatidylcholines (PCs) with c9,t11-CLA, t10,c12-CLA, and linoleic acid (LA) in the sn-2 position into natural PCs from soybean, egg yolk, rat brain, and rat heart at 5 mol %. The oxygen diffusion-concentration products were measured using electron spin resonance spin-label oximetry methods. Individual synthetic PCs, the phospholipid matrix, and the tested lipid systems all exhibited influence on oxygen diffusion-concentration products during lipid peroxidation. Incorporating 5 mol % PC(c9,t11-CLA) into soy and egg yolk PC increased oxygen consumption in liposome suspensions while it was decreased in rat heart and brain PCs. On the other hand, PC(t10,c12-CLA) increased oxygen consumption in mixtures with egg yolk and rat heart PC but decreased it in soybean and rat brain PC. By comparison, PC(LA) decreased oxygen consumption in every case. In ethanol solutions, all of the synthetic PCs suppressed the capacity to generate peroxide radicals in the order of LA > c9,t11-CLA > t10,c12-CLA. In addition, PCs containing individual CLA isomers and LA differed in their capacities to react with and quench DPPH radicals in both ethanol solution and liposome, suggesting differences between CLA isomers and LA in DPPH radical-fatty acid interactions. Incorporation of CLA isomers and LA into dimyristyl-PC reduced the phase transition temperature from 23.6 to 23.1 and 23.3 degrees C, respectively. The results of this study provide evidence that the behavior of CLA isomers differs in the microenvironment of membranes possibly due to structural differences that affect the permeability of membranes to oxygen and lipid peroxidation.

Differential effects of conjugated linoleic acid isomers on macrophage glycerophospholipid metabolism

“…2A ) using the abovedescribed model for CCT activation by membrane curvature stress. It is also supported by data from Yin et al showing that incorporation of c9,t11 -CLA into phospholipids substantially alters physical membrane properties and function ( 36,37 ). However, another possible explanation for the enhanced PL synthesis rates might be that c9,t11 -CLA treatment enhances PC and PE synthesis by increasing the diacylglycerol (DAG) content necessary for the last step of the Kennedy pathway (supplementary Fig.…”

Inhibition of Tumor Growth by Endohedral Metallofullerenol Nanoparticles Optimized as Reactive Oxygen Species Scavenger

“…Following our previously established methodology (Yin et al, 2006), ESR spectroscopy was used to measure scavenging of the DPPH ⅐ free radical by [Gd@C 82 (OH) 22 ] n nanoparticles (Murias et al, 2005). Although DPPH ⅐ is a stable, nitrogen-centered radical that has no involvement in physiological processes, attenuation of the ESR signal for DPPH ⅐ is one of the methods widely used to demonstrate the ability of a chemical to scavenge reactive oxygen species through donation of a hydrogen atom, or, in some cases, electron transfer (Huang et al, 2005).…”

“…Because O 2 is paramagnetic, this collision results in spin exchange between O 2 and the spin probe, resulting in shorter relaxation times (both T 1 and T 2 ). Consequently, ESR signals with broader line widths are observed for the spin probe (Yin et al, 2006). Because the integrated area of the ESR signal over the scanning range is unaffected by these effects on the relaxation times, broadening of the ESR signal of the spin probe is necessarily accompanied by a decrease in the peak height of the ESR signal.…”

Effect of dietary conjugated linoleic acid isomers on water and glycerol permeability of kidney membranes

“…An increase in bilayer permeability has also been reported 335 for liposomes containing CLA isomers [29].…”

“…Dietary CLA has been associated with various health benefits 27 although details of its molecular mode of action remain elusive. The effect of CLA supplemented to palm 28 oil-based diets in Wistar rats, as a mixture of both or isolated c9,t11 and t10,c12 isomers, was examined 29 on water and glycerol membrane permeability of kidney proximal tubule. Although water permeability 30 was unaltered, an increase in glycerol permeability was obtained for the group supplemented with CLA 31 mixture, even though the activation energy for glycerol permeation remained high.…”