Thermodynamic characterization of the prevailing molecular interactions in mixed floating monolayers of phospholipids and usnic acid

Andrade, César A.S.; Santos-Magalhães, Nereide Stela; Melo, Celso P. de

doi:10.1016/j.jcis.2005.11.066

Cited by 17 publications

(18 citation statements)

References 26 publications

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“…Among several lichen constituents, (þ)-usnic acid (UA) enantiomer exhibits a stronger tumors inhibitory activity than that of (À)-enantiomer (Yamamoto et al, 1995). Nevertheless, practical use of this molecule in anticancer therapy has been rather limited due to its poor solubility in water (less than 0.1 mg Á ml À1 at 258C) (Andrade et al, 2006). Since solubility improvements represent a serious challenge when foreseeing biomedical applications of (þ)-UA, it was the aim of this work to investigate the possibility for (þ)-UA to interact with cyclodextrins (CDs) and to determine the thermodynamic characteristics of their complexes.…”

Section: Introductionmentioning

confidence: 99%

Elucidation of the complexation mechanism between (+)‐usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase‐solubility diagram experiments

Segura‐Sánchez¹,

Bouchemal²,

Lebas³

et al. 2009

J of Molecular Recognition

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In the present work the complexation mechanism between (+)-usnic acid (UA) and cyclodextrins (CDs) has been investigated by isothermal titration calorimetry (ITC) and phase-solubility diagrams using pH as a tool for modifying the molecule ionization. ITC experiments have been employed to evaluate the stoichiometry of interaction (N), affinity constants (K), and thermodynamic parameter variation associated with complexation between (+)-UA and alpha-, beta-, HP-beta-, SBE-beta-, and gamma-CD. It was shown that (+)-UA did not interact with alpha-CD and tended to interact more favorably with gamma-CD (K = 1030 M(-1), DeltaG = -17.18 kJ x mol(-1)) than beta-CD (K = 153 M(-1), DeltaG = -12.46 kJ x mol(-1)) forming 1:1 complexes. It was also demonstrated using ITC and solubilization experiments that chemical modifications of the parent beta-CD resulted in stronger and more spontaneous interactions (K = 281 M(-1), DeltaG = -13.97 kJ x mol(-1) for SBE-beta-CD and K = 405 M(-1), DeltaG = -14.87 kJ x mol(-1) for HP-beta-CD). Analysis of the thermodynamic data suggested that van der Waals forces and hydrogen bonds were responsible for the formation of complexes with a predominance of van der Waals forces. Finally, pH induced modifications of (+)-UA ionization provided important informations relative to the topology of the interaction between (+)-UA molecule and the gamma-CD cavity, which were confirmed by molecular modeling.

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Section: Introductionmentioning

confidence: 99%

Elucidation of the complexation mechanism between (+)‐usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase‐solubility diagram experiments

Segura‐Sánchez¹,

Bouchemal²,

Lebas³

et al. 2009

J of Molecular Recognition

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“…The values of A 0 of the Chol-HDL or Chol-LDL mixed monolayers were less than the A 0 of the pure HDL or LDL monolayers ( Table 2 ). The ideal mean molecular areas of a mixed monolayer ( A id ) can be calculated using [ 25 ]:

Here, X 1 and X 2 are the molar fractions of component 1 or 2 in the mixed monolayers. A 1 and A 2 are the area per molecules of components 1 and 2, respectively, in a pure monolayer of component 1 or component 2.…”

Section: Resultsmentioning

confidence: 99%

Interaction of different lipoprotein types with cholesterol at the air/water interface

Ninomiya

McNamee

2020

Heliyon

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Cholesterol (Chol) interacts with lipoproteins, in order to be transported through the aqueous bloodstream. High density lipoproteins (HDL) and low density lipoproteins (LDL) transport cholesterol differently, a result that may be due to a difference in their interactions with cholesterol. Here, we investigated how the lipoprotein type affects the interaction with cholesterol by using a Langmuir trough and fluorescence microscope. We studied pure monolayers of 1) Chol, 2) LDL, and 3) HDL, and mixed monolayers of 1) Chol-LDL, and 2) Chol-HDL at air/water interfaces. Images of the Chol-LDL mixed monolayer showed many small sterol domains distributed in the non-sterol molecules (e.g. phospholids, proteins and lipids) of LDL. The sterol domains that were seen in the Chol-HDL mixed monolayer were larger in size but smaller in number than those seen in the Chol-LDL mixed monolayers. These images and the excess area, excess free energy, and free energy of mixing values obtained from the thermodynamic analysis of the surface pressure-area per molecule isotherms suggested that the cholesterol phase separated more from HDL than from LDL. Cholesterol was therefore concluded to interact with LDL better than with HDL. This more favorable interaction was explained by the presence of hydrophobic interactions between cholesterol and Apo-B, the major apoprotein of LDL.

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“…Such monolayer studies can be used to thermodynamically analyse interactions between components in mixed monolayers, allowing interactions between lipid components and their molecular arrangement at the air/water interface 26. It is clear that the structural differences of lipids influence the interactions among them and these interactions dominate the organisation of membranes 27. Many studies have been conducted on the behaviour of different lipids in mixed monolayers28,29 and these can be used to interpret the interaction in liposome bilayers 20,30.…”

Section: Resultsmentioning

confidence: 99%

“…26 It is clear that the structural differences of lipids influence the interactions among them and these interactions dominate the organisation of membranes. 27 Many studies have been conducted on the behaviour of different lipids in mixed monolayers 28,29 and these can be used to interpret the interaction in liposome bilayers. 20,30 Surface properties of mixed monolayers are generally studied on the basis of surface pressure (π)/mean molecular area (A) measurements in which bidimensional phases can be detected, each separated by a phase transition.…”

Section: Langmuir-blodgett Isothermsmentioning

confidence: 99%

Preparation, Characterisation and Entrapment of a Non-glycosidic Threitol Ceramide into Liposomes for Presentation to Invariant Natural Killer T Cells

Kaur

Chen

Dawoodji

et al. 2011

Journal of Pharmaceutical Sciences

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Dendritic cells (DCs) are able to present glycolipids to invariant natural killer T (iNKT) cells in vivo. Very few compounds have been found to stimulate iNKT cells, and of these, the best characterised is the glycolipid α-galactosylceramide, which stimulates the production of large quantities of interferon-gamma (IFN-γ) and interleukin-4 (IL-4). However, αGalCer leads to overstimulation of iNKT cells. It has been demonstrated that the αGalCer analogue, threitol ceramide (ThrCer 2), successfully activates iNKT cells and overcomes the problematic iNKT cell activation-induced anergy. In this study, ThrCer 2 has been inserted into the bilayers of liposomes composed of a neutral lipid, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), or dimethyldioctadecylammonium bromide (DDA), a cationic lipid. Incorporation efficiencies of ThrCer within the liposomes was 96% for DSPC liposomes and 80% for DDA liposomes, with the vesicle size (large multilamellar vs. small unilamellar vesicles) making no significant difference. Langmuir-Blodgett studies suggest that both DSPC and DDA stack within the monolayer co-operatively with the ThrCer molecules with no condensing effect. In terms of cellular responses, IFN-γ secretion was higher for cells treated with small DDA liposomes compared with the other liposome formulations, suggesting that ThrCer encapsulation in this liposome formulation resulted in a higher uptake by DCs.

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Thermodynamic characterization of the prevailing molecular interactions in mixed floating monolayers of phospholipids and usnic acid

Cited by 17 publications

References 26 publications

Elucidation of the complexation mechanism between (+)‐usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase‐solubility diagram experiments

Elucidation of the complexation mechanism between (+)‐usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase‐solubility diagram experiments

Interaction of different lipoprotein types with cholesterol at the air/water interface

Preparation, Characterisation and Entrapment of a Non-glycosidic Threitol Ceramide into Liposomes for Presentation to Invariant Natural Killer T Cells

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