Gel-state metastability and nature of the azeotropic points in mixtures of saturated phosphatidylcholines and fatty acids

Koynova, Rumiana; Boyanov, A.; Tenchov, Boris

doi:10.1016/0005-2736(87)90168-4

Cited by 53 publications

(29 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Calculated amounts of DPPC and nicotinate were dissolved in chloroform-methanol (3:1, v/v) at the appropriate mole fractions (25). The solvent was removed under a stream of nitrogen, and the mixtures were further dried under vacuum for at least 3 h. The samples (a mixture of phospholipid and nicotinate or pure phospholipid) were hydrated in an excess of water (three times by weight).…”

Section: Preparation Of Samples For Dscmentioning

confidence: 99%

“…The DSC cell and the refrigerated cooling system were purged with 60 and 120 ml/min dry nitrogen, respectively. Samples were cooled to 4 Њ C at a cooling rate of 10 Њ C/min and then heated from 4 Њ C to 80 Њ C with a heating rate of 5 Њ C/min (16,(24)(25)(26). All samples were subjected to two subsequent heating cycles.…”

Section: Preparation Of Samples For Dscmentioning

confidence: 99%

See 1 more Smart Citation

Interaction of long-chain nicotinates with dipalmitoylphosphatidylcholine

Lehmler

Fortis-Santiago

Nauduri

et al. 2005

Journal of Lipid Research

View full text Add to dashboard Cite

The interaction of four long-chain nicotinates, compounds that are of interest as potential chemopreventive agents, with dipalmitoylphosphatidylcholine (DPPC) was investigated in monolayers at the air-water interface and in fully hydrated bilayers. For the monolayer studies, the compression isotherms of mixtures of the respective nicotinate with DPPC were recorded at various compositions on a hydrochloric acid subphase (pH 1.9-2.1, 37 ؎ 2 ؇ C). The headgroup of the nicotinates (24-29 Å 2 /molecule) is larger than that of the hydrophobic tail (20 Å 2 /molecule). The pure nicotinates exhibit a temperature-and chain lengthdependent transition from an expanded to a condensed phase. Analysis of the concentration dependence of the average molecular area at constant film pressure and the concentration dependence of the breakpoint of the phase transition from the expanded to the condensed state suggests that all four DPPC-nicotinate mixtures are partially miscible at the air-water interface. Although a complex phase behavior with several phase transitions was observed, differential scanning calorimetry studies of the four mixtures are also indicative of the partial miscibility of DPPC and the respective nicotinate.Overall, the complex phase behavior most likely results from the head-tail mismatch of the nicotinates and the geometric packing constraints in the twocomponent lipid bilayer. Nicotinic acid and its alkyl esters are of considerable biological and pharmacological importance. Besides being the precursor of cofactors to many vital enzymes, nicotinic acid is a drug possessing vasodilating and fibrinolytic properties. Nicotinic acid itself has been proven beneficial against bleomycin-and cyclophosphamide-induced lung injury in animal models (1-5). Dietary supplements of nicotinic acid and dermatologic formulations of its longchain esters are under investigation for the prevention and treatment of skin carcinogenesis (6). Therefore, nicotinic acid esters may be useful as a chemopreventive agent for the prevention of lung cancer.Currently, there is significant interest in the pulmonary administration of several chemopreventive agents, such as steroids and retinoids, directly to the lung because of reduced systemic toxicity (7-11). This route of administration may also be advantageous for the administration of nicotinic acid esters, by using either an aerosol or a perfluorocarbon vehicle (12, 13). Although the interaction of various chemopreventive agents, especially retinoids, with phospholipids has been investigated (14, 15), there is no current knowledge about the factors that determine the interaction (i.e., phase behavior) of nicotinates with biological lipids such as the phospholipids present in pulmonary surfactant. A better understanding of these interactions, however, is a prerequisite for the rational design of nicotinates for pulmonary administration, especially using a perfluorocarbon-based drug delivery system (12, 13). The aim of this study is to understand which molecular characteristics influe...

show abstract

Section: Preparation Of Samples For Dscmentioning

confidence: 99%

Section: Preparation Of Samples For Dscmentioning

confidence: 99%

Interaction of long-chain nicotinates with dipalmitoylphosphatidylcholine

Lehmler

Fortis-Santiago

Nauduri

et al. 2005

Journal of Lipid Research

View full text Add to dashboard Cite

show abstract

“…DPPC and 10-(perfluorohexyl)-decanol were dissolved in chloroform -methanol (3:1,v\v) at the appropriate mole fractions [21]. The solvent was removed under a stream of nitrogen, and the mixtures were further dried under vacuum for at least 3 hours.…”

Section: Differential Scanning Calorimetry Experimentsmentioning

confidence: 99%

“…The DSC cell and the refrigerated cooling system were purged with 60 mL\min and 120 mL/min of dry nitrogen, respectively. Samples were cooled to 4°C at a heating rate of 10°C/min and then heated from 4°C to 80°C with a heating rate of 5°C/min [13,14,21,22]. All samples were subjected to two subsequent heating cycles.…”

Section: Differential Scanning Calorimetry Experimentsmentioning

confidence: 99%

Mixing behavior of 10-(perfluorohexyl)-decanol and DPPC

Lehmler

Bummer

2005

Colloids and Surfaces B: Biointerfaces

View full text Add to dashboard Cite

Fluorocarbon alcohol such as 10-(perfluorohexyl)-decanol are of interest for novel pulmonary drug delivery approaches. The purpose of this study was to investigate the mixing behavior of 10-(perfluorohexyl)-decanol with dipalmitoylphosphatidylcholine (DPPC), the major component of lung surfactant, as an aid in assessing usefulness for this and other biomedical applications. The impact of 10-(perfluorohexyl)-decanol on the phase transitions of DPPC bilayers fully hydrated with a 0.15 M sodium chloride solution were studied using differential scanning calorimetry (DSC). No peak corresponding to excess alcohol was observed. The fluorinated alcohol caused DPPC peak broadening, especially below X DPPC < 0.95, and elimination of the pretransition of DPPC at X DPPC ∼ 0.91. The onset of the main phase transition remains constant down to X DPPC ∼ 0.91, suggesting limited miscibility in the gel phase. Hydration of the 10-(perfluorohexyl)-decanol-DPPC mixtures with calcium chloride (2 mM) in place of sodium chloride did not alter the macroscopic phase behavior. In addition to the thermal properties, the miscibility of 10-(perfluorohexyl)-decanol in DPPC in monolayers at the air water interface was investigated on water, sodium chloride (0.15 M), calcium chloride (2 mM) or hydrochloric acid (pH=1.9) subphases. The concentration dependence of the onset pressure of the liquid-expanded to liquid condensed phase transition of DPPC showed a slight change with increasing mole fraction on all four subphases. The surface areamole fraction diagrams of 10-(perfluorohexyl)-decanol and DPPC on water, sodium chloride and calcium chloride showed near ideal behavior with slight negative deviations at higher surface pressure. A more significant negative deviation was observed for the hydrochloric acid subphase. Overall, both the DSC and the monolayer studies suggest that 10-(perfluorohexyl)-decanol and DPPC are partially miscible in biological mono-and bilayers. The macroscopic phase behavior 10-(perfluorohexyl)-decanol-DPPC system is significantly different from the analogous hydrocarbon system, which is attributed to a less favorable packing of the partially fluorinated hydrophobic tails in the mono-and bilayer.

show abstract

“…The thermotropic phase transitions in the lipid dispersions were recorded using a high-sensitivity DASM-1M microcalorimeter as described previously [ 16 ]. The heating rate was 0.5 ° C min-1.…”

Section: Calorimetric Measurementsmentioning

confidence: 99%

Liposome—glass interaction. Influence of the lipid bilayer phase state

Tenchov

Petsev

Koynova

et al. 1989

Colloids and Surfaces

View full text Add to dashboard Cite

The adsorption of dipalmitoylphosphatidylcholine (DPPC) and palmitic acid from multilamellar lipid dispersions in excess water onto hydrophilic and hydrophobic glass surfaces was studied. Adsorption isotherms at different temperatures were obtained. The adsorbed lipid amount at saturation, F~, was found to depend strongly on the phase state of the lipid dispersion. For DPPC, a sharp decrease of F~o was observed at the gel-liquid crystal phase transition at 41 °C (P~-L~). The DPPC adsorption from the gel phases Lp. and Pz' was significantly greater than that from the low-temperature crystalline Lc phase. The Lc-isotropic phase transition of palmitic acid was also clearly reflected in the temperature dependence of F~ for this lipid. Electron microscopy yielded direct evidence for the presence of lipid aggregates and restructured liposomes on the glass surface. In combination with the adsorption data, this shows that fluid liposomes bind less to glass surfaces than solid liposomes.

show abstract

Gel-state metastability and nature of the azeotropic points in mixtures of saturated phosphatidylcholines and fatty acids

Cited by 53 publications

References 23 publications

Interaction of long-chain nicotinates with dipalmitoylphosphatidylcholine

Interaction of long-chain nicotinates with dipalmitoylphosphatidylcholine

Mixing behavior of 10-(perfluorohexyl)-decanol and DPPC

Liposome—glass interaction. Influence of the lipid bilayer phase state

Contact Info

Product

Resources

About