The role of lipophilicity in transmembrane anion transport

Saggiomo, Vittorio; Otto, Sijbren; Marques, Igor; Félix, Vı́tor; Torroba, Tomás; Quesada, Roberto

doi:10.1039/c2cc31825c

Cited by 93 publications

(75 citation statements)

References 28 publications

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“…It has often been suggested that ion transport across lipid bilayers is diminished when receptors become too lipophilic to interact with the ions at the lipid-water interphase. 12,24,41,42 In order to obtain an estimate of the lipophilicity of compounds 1–8, experimental retention times on reversed-phase HPLC 43 were determined (Table 3). It is clear that the three inactive transporters are also the receptors with the highest lipophilicity (highest retention time), suggesting that lipophilicity may also contribute to the inactivity of 4, 7 and 8 .…”

Section: Resultsmentioning

confidence: 99%

Thiosquaramides: pH switchable anion transporters

et al. 2014

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The transport of anions across cellular membranes is an important biological function governed by specialised proteins. In recent years, many small molecules have emerged that mimick the anion transport behaviour of these proteins, but only a few of these synthetic molecules also display the gating/switching behaviour seen in biological systems. A small series of thiosquaramides was synthesised and their pH-dependent chloride binding and anion transport behaviour was investigated using 1H NMR titrations, single crystal X-ray diffraction and a variety of vesicle-based techniques. Spectrophotometric titrations and DFT calculations revealed that the thiosquaramides are significantly more acidic than their oxosquaramide analogues, with pKa values between 4.0 and 9.0. This led to the observation that at pH 7.2 the anion transport ability of the thiosquaramides is fully switched OFF due to deprotonation of the receptor, but is completely switched ON at lower pH.

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Section: Resultsmentioning

confidence: 99%

Thiosquaramides: pH switchable anion transporters

et al. 2014

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“…The vesicles were dispersed in an aqueous external solution of sodium nitrate (489 mM NaNO 3 buffered to pH 7.2 with 5 mM sodium phosphate salts). 26 The most active compounds in this series lie either in or just outside this range. Receptors 1-6 were loaded at an appropriate molar percentage relative to the moles of lipid as a DMSO solution at 0 s and the resulting chloride efflux from the vesicles detected by a chloride selective electrode (Accumet).…”

Section: Anion Transport Studies and Hill Analysismentioning

confidence: 99%

Aromatic isophthalamides aggregate in lipid bilayers: evidence for a cooperative transport mechanism

et al. 2015

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The synthesis and anion transport properties of a series of transmembrane anion transporters based on an isophthalamide scaffold with phenyl, naphthyl or anthracenyl central rings are reported. Anion transport studies using POPC vesicles, showed that the compounds have Hill coefficients >1. This is indicative of higher order complex formation, evidence that leads us to suggest that the compounds are not functioning solely as mobile carriers but rather that a cooperative transport mechanism is being observed. Fluorescence spectroscopy was used to show that the compounds aggregate in the phospholipid bilayer, which provides evidence that these compounds function as a self-assembled anion-conducting aggregate.

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“…Figure 2 shows their transport takes longer to begin following the addition of the receptor to the system, giving more of a sigmoidal shape to the curve, receptor 6 also displays a more sigmoidal shape in the Hill plot. This behaviour has previously been noted by Haynes et al (24) which was attributed to the receptors lying outside the optimum lipophilicity values proposed by Saggiomo et al (25) Receptors 5 and 6 possess log P values of 5.1 and 5.44 respectively as calculated by VCC labs, (26) which lie above the optimum lipophilicity values proposed (log P < 4) (25). This would allow the slow start to transport to be rationalised, as delivery through the aqueous external solution is hindered.…”

Section: Resultsmentioning

confidence: 53%

Anion transport and binding properties of N N′-(phenylmethylene)dibenzamide based receptors

Clarke

Rossom

Light

et al. 2015

Supramolecular Chemistry

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Dedicated to friend and mentor Professor Jonathan L. Sessler on the occasion of his 60th birthday.The anion transport and binding properties of a series of bis-amide based compounds have been studied in POPC lipid bilayers. The compounds display evidence of aggregation in solution with single crystal X-ray crystallographic analysis showing hydrogen bonding between the amide substituents of adjacent receptors in the solid state.

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The role of lipophilicity in transmembrane anion transport

Abstract: The transmembrane anion transport activity of a series of synthetic molecules inspired by the structure of tambjamine alkaloids can be tuned by varying the lipophilicity of the receptor, with carriers within a certain log P range performing best.

Cited by 93 publications

References 28 publications

Thiosquaramides: pH switchable anion transporters

Thiosquaramides: pH switchable anion transporters

Aromatic isophthalamides aggregate in lipid bilayers: evidence for a cooperative transport mechanism

Anion transport and binding properties of N N′-(phenylmethylene)dibenzamide based receptors

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