Partitioning of Tetrachlorophenol into Lipid Bilayers and Sarcoplasmic Reticulum: Effect of Length of Acyl Chains, Carbonyl Group of Lipids and Biomembrane Structure

Word, Robert Campbell; Smejtek, P.

doi:10.1007/s00232-005-0737-8

Cited by 7 publications

(7 citation statements)

References 35 publications

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“…Figure 3 shows generally higher Klipw for the neutral species than for the ionic ones. The uptake of the latter is decreased due to their charge (12,38,39). Nevertheless, the uptake of the charged species is only one to two magnitudes lower than that for the neutral species.…”

Section: Resultsmentioning

confidence: 97%

The Evaluation of Liposome-Water Partitioning of 8-Hydroxyquinolines and Their Copper Complexes

Kaiser

Escher

2006

Environ. Sci. Technol.

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Bioavailability and toxicity of mixtures are urgent research issues, but usually mixtures of exclusively organic chemicals or exclusively metals are investigated. In our study, we explored the role of combinations of hydrophobic ionogenic organic compounds (HIOCs) with copper (Cu2+)for uptake and bioavailability of metals and hydrophobic metal complexes in an in vitro membrane system. We investigated the influence of the interactions of copper and 8-hydroxyquinolines, both components used in formulations of pesticides, on their partitioning into liposomes, which are model systems for biological membranes and are composed of lipid bilayers made of phosphatidylcholine. The test set of compounds comprised the parent compound 8-hydroxyquinoline and 8-hydroxyquinolines with hydrophobic (e.g., 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline) and with hydrophilic (e.g., 8-hydroxyquinoline-5-sulfonic acid) substituents. Hydrophobic 8-hydroxyquinolines facilitate the passive uptake of copper into phospholipid bilayers by complex formation. Not only the neutral species of the ligands and their neutral copper ligand complexes are significantly taken up into the membrane, but also the cationic and anionic species of the ligands and the cationic complexes. The neutral, anionic, and cationic species of 8-hydroxyquinoline and the hydrophobic substituted 8-hydroxyquinolines exhibit linear correlations between their logarithmic liposome-water partitioning coefficients (log Klipw) and the logarithmic octanol-water partitioning coefficients of their neutral species (log Kow, neutral). The neutral species show the strongest partitioning followed by the anionic and cationic species. The associated quantitative structure activity relationships describing the dependency of log Klipw of the various species from log Kow, neutral of the neutral ligand species have slopes between 0.9 and 1. In contrast, the partitioning of the neutral and cationic copper-8-hydroxyquinoline complexes is dependent on several factors including the hydrophobicity of the ligand, the effective molecular size, and the polarization of the complex itself. In consequence, there is no linear relationship between log Klipw of these complexes and log Kow of the neutral species of their ligands. The complexes with very bulky substituents showed a reduced uptake. The Klipw of the nominally neutral complexes, where Cu2+ is coordinated with two ligands, were a factor three to four higher than the Klipw of the positively charged complexes with only one ligand. Although liposome-water partitioning merely describes one element of the uptake process into biological membranes, it is a key process for bioavailability of hydrophobic compounds and, presumably, also plays a crucial role for biological uptake of the described metal organic complexes.

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Section: Resultsmentioning

confidence: 97%

The Evaluation of Liposome-Water Partitioning of 8-Hydroxyquinolines and Their Copper Complexes

Kaiser

Escher

2006

Environ. Sci. Technol.

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“…In theory, the partition coefficient in an octanol−water mixture (log P ) is independent of the concentration. However, a negative concentration dependency could be expected for the membrane−water partitioning because the binding sites in the bilayer are limited, , which will probably be achieved at higher EBA concentrations. The experimentally determined increase in sorption may be explained from the fluidizing effect, emphasizing again the importance of the membrane fluidity of the bilayer on the sorption affinity.…”

Section: Resultsmentioning

confidence: 99%

NMR Study of the Sorption Behavior of Benzyl Alcohol Derivatives into Sonicated and Extruded Dioctadecyldimethylammonium Chloride (DODAC) Dispersions: The Relevance of Membrane Fluidity

et al. 2008

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The sorption behavior of three benzyl alcohol derivatives with different hydrophobicities into sonicated and extruded DODAC dispersions has been studied using NMR spectroscopy and NMR diffusometry. We show that there is an increased sorption into a sonicated dispersion below the phase-transition temperature (T(m)) as compared to an extruded dispersion. This may be explained by the incomplete lipid chain freezing of charged lipids as a result of the sonication process. Around T(m), a sorption maximum is found that is attributed to the high bilayer disorder under this condition. In addition, a sorption increase and a fluidizing effect at increasing benzyl alcohol derivative concentrations are observed that provide additional evidence for the relevance of the bilayer fluidity on the sorption of hydrophobic components.

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“…1 The properties of both the drug and the membrane affect partitioning of the drug into lipid bilayers. [2][3][4][5][6] Below the gelto-liquid-crystalline phase transition temperature (T m ), the surfactant molecules in the vesicle bilayer possess more solid phase-like alkyl chains. Above T m , the surfactant molecules are in the liquidcrystalline state and conformational disorder predominates in the alkyl chains.…”

Section: Introductionmentioning

confidence: 99%

“…5 Word et al reported a constant membranewater molar partitioning with a decrease in alkyl chain length or, in other words, equal sorption with a decrease in alkyl chain length when the molar concentration of the lipids is kept constant. 6 To investigate whether sorption can be predicted well by a water-bilayer partition coefficient in which the lipid volume is the main factor, we investigated the effect of the bilayer structure on the sorption behavior of 4-ethylbenzyl alcohol (EBA) in either phosphatidylcholine or DODAB vesicles. Phosphatidylcholines were selected because different chain lengths are commercialy available in highly pure form.…”

Section: Introductionmentioning

confidence: 99%

“…Liu et al reported that lipids with short chains or more unsaturation provide a more fluid membrane environment that favors drug partitioning in phosphatidylcholines . Word et al reported a constant membrane−water molar partitioning with a decrease in alkyl chain length or, in other words, equal sorption with a decrease in alkyl chain length when the molar concentration of the lipids is kept constant . To investigate whether sorption can be predicted well by a water−bilayer partition coefficient in which the lipid volume is the main factor, we investigated the effect of the bilayer structure on the sorption behavior of 4-ethylbenzyl alcohol (EBA) in either phosphatidylcholine or DODAB vesicles.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Vesicular Bilayer Structure on the Sorption of Ethylbenzyl Alcohol

et al. 2009

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The influence of the physicochemical properties of the vesicular bilayer on the sorption of poorly water soluble compounds was investigated with pulsed field gradient 1H nuclear magnetic resonance (PFG-NMR) for the case of phosphatidylcholine and dioctadecyldimethylammonium bromide (DODAB), using 4-ethylbenzyl alcohol as a model compound. Hereby, the effect of bilayer thickness at a constant physicochemical state was studied using a range of phosphatidylcholines of varying chain lengths, whereas DODAB was preferred to check the influence of the bilayer physicochemical state since this cationic lipid is characterized by three different states within the studied temperature range. When the phospholipid alkyl chain length was changed, no differences were observed in the sorption which was linked to the surface-mediated sorption. On the other hand, when the chemical composition was preserved but the temperature and thus the physical state of the bilayer were changed, the sorption in dioctadecyldimethylammonium bromide (DODAB) vesicles changed dramatically. From those experiments, a strong relationship between the ordering of the surfactant molecules and the sorption can be assumed.

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Partitioning of Tetrachlorophenol into Lipid Bilayers and Sarcoplasmic Reticulum: Effect of Length of Acyl Chains, Carbonyl Group of Lipids and Biomembrane Structure

Cited by 7 publications

References 35 publications

The Evaluation of Liposome-Water Partitioning of 8-Hydroxyquinolines and Their Copper Complexes

The Evaluation of Liposome-Water Partitioning of 8-Hydroxyquinolines and Their Copper Complexes

NMR Study of the Sorption Behavior of Benzyl Alcohol Derivatives into Sonicated and Extruded Dioctadecyldimethylammonium Chloride (DODAC) Dispersions: The Relevance of Membrane Fluidity

Influence of the Vesicular Bilayer Structure on the Sorption of Ethylbenzyl Alcohol

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