Evaluation of phase transition temperature of liposomes by using the tautomerism of α-Benzoylacetoanilide

Ueno, Minoru; Katoh, Shinji; Kobayashi, Shinichi; Tomoyama, E; Ohsawa, Shigemitsu; Koyama, Noritoshi; Morita, Yutaka

doi:10.1016/0021-9797(90)90167-m

Cited by 12 publications

(8 citation statements)

References 16 publications

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“…The DSPC model was tested by running two simulations under different conditions, to reproduce the different phases characteristic of this lipid species. In fact, DSPC membranes are observed experimentally to form solid (gel) bilayers at temperatures below [103] , [104] ; above , DSPC forms fluid-phase bilayers. One simulation was therefore run under “gel phase conditions”; in particular, run G was conducted at and 12 waters/lipid (as in corresponding experiments [105] ).…”

Section: Resultsmentioning

confidence: 99%

The ELBA Force Field for Coarse-Grain Modeling of Lipid Membranes

2011

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A new coarse-grain model for molecular dynamics simulation of lipid membranes is presented. Following a simple and conventional approach, lipid molecules are modeled by spherical sites, each representing a group of several atoms. In contrast to common coarse-grain methods, two original (interdependent) features are here adopted. First, the main electrostatics are modeled explicitly by charges and dipoles, which interact realistically through a relative dielectric constant of unity (). Second, water molecules are represented individually through a new parametrization of the simple Stockmayer potential for polar fluids; each water molecule is therefore described by a single spherical site embedded with a point dipole. The force field is shown to accurately reproduce the main physical properties of single-species phospholipid bilayers comprising dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE) in the liquid crystal phase, as well as distearoylphosphatidylcholine (DSPC) in the liquid crystal and gel phases. Insights are presented into fundamental properties and phenomena that can be difficult or impossible to study with alternative computational or experimental methods. For example, we investigate the internal pressure distribution, dipole potential, lipid diffusion, and spontaneous self-assembly. Simulations lasting up to 1.5 microseconds were conducted for systems of different sizes (128, 512 and 1058 lipids); this also allowed us to identify size-dependent artifacts that are expected to affect membrane simulations in general. Future extensions and applications are discussed, particularly in relation to the methodology's inherent multiscale capabilities.

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Section: Resultsmentioning

confidence: 99%

The ELBA Force Field for Coarse-Grain Modeling of Lipid Membranes

2011

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“…The decrease in r values at 50 ºC is low in DSPC:DMPG (5:1) vesicles, due to the higher melting transition temperature of DSPC (T m = 55 ºC [13]), as this phospholipid is still in the gel phase at 50 ºC. This fact can also contribute to the more hydrated environment reported by these compounds in DSPC:DMPG liposomes, as the rigidity of these membranes can prevent the compounds to penetrate more deeper in the lipid membranes.…”

Section: Fluorescence Studies In Nanoliposomesmentioning

confidence: 96%

“…Melting points ( o C) were determined in a SMP3 Stuart apparatus and are uncorrected. 1 H and 13 C NMR spectra were recorded on a Bruker Avance III at 400 and 100.6 MHz, respectively. Heteronuclear correlations, 1 H- 13 C, HMQC or HSQC were performed to attribute some signals.…”

Section: 11general Remarksmentioning

confidence: 99%

“…1 H NMR (CDCl 3 , 400 MHz): δ 3.81 (3H, s, OMe), 3.89 (3H, s, OMe), 6.21 (2H, s largo, NH 2 ), 6.99-7.01 (1H, m, Ar-H), 7.06 (1H, dd, J = 8.4 e 1.6 Hz, ArH), 7.12 (1H, dd, J = 8.0 e 1.6 Hz, ArH), 7.24-7.38 (1H, m, Ar-H), 7.34 (1H, d, J = 2.4 Hz, HetAr), 8.46 (1H, d, J = 2.4 Hz, HetAr) ppm. 13 Thieno [3,2-b]pyridine 1 (150 mg, 0.545 mmol) and 3-methoxyphenol (1.3 equiv, 0.1 mL, 0.709 mmol), were heated and the reaction mixture was treated according to the general procedure. Column chromatography using 40% diethylether/petroleum ether gave compound 2b as a yellow solid (96.0 mg, 53%), m.p.…”

Section: General Procedures For the Copper-catalyzed C-o (Scheme 1)mentioning

confidence: 99%

“…All the solutions were prepared using spectroscopic grade solvents and ultrapure water Nanoliposomes were prepared by evaporation of a mixture of lipids and compound in chloroform under vacuum for 12 h. The lipid/compound film was then hydrated with an aqueous buffer solution (10 mM Tris-HCl buffer, pH=7.4), above the lipids melting transition temperature (ca. 41 ºC for DPPC [11], 23 ºC for DMPG [12], 55 ºC for DSPC [13] and 45 ºC for DODAB [14]), followed by six extrusion cycles (using a LIPEX TM extruder) through 100 nm polycarbonate membranes. Between the extrusion cycles, the solutions were allowed to equilibrate for 1 h. The final total lipid concentration was 1 mM, with a compound/lipid molar ratio of 1:333.…”

Section: Liposomes Preparationmentioning

confidence: 99%

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New potential antitumoral di(hetero)arylether derivatives in the thieno[3,2-b]pyridine series: Synthesis and fluorescence studies in solution and in nanoliposomes

Queiroz

Dias

Peixoto

et al. 2012

Journal of Photochemistry and Photobiology A: Chemistry

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New fluorescent methoxylated di(hetero)arylethers in the thieno [3,2-b]pyridine series were prepared by a copper-catalyzed Ullmann-type C-O coupling of the methyl 3-amino-6-bromothieno[3,2b]pyridine-2-carboxylate with ortho, meta and para-methoxyphenols, using N,N-dimethylglycine as the ligand and Cs 2 CO 3 as the base. The compounds obtained were tested for their inhibitory growth activity in three human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer). The di(hetero)arylethers bearing a methoxy group in the ortho and meta positions showed very low GI 50 values (1.1−2.5 µM) in all the three tumor cell lines. Their fluorescence properties in solution and when encapsulated in different nanoliposome formulations, composed either by egg-yolk phosphatidylcholine (Egg-PC), dipalmitoyl phosphatidylcholine (DPPC), dimyristoyl phosphatidylglycerol (DMPG), dioctadecyldimethylammonium bromide (DODAB), distearoyl phosphatidylcholine (DSPC), with or without cholesterol (Ch), or distearoyl phosphatidylethanolamine-(polyethylene glycol)2000 (DSPE-PEG), were studied. All compounds can be carried in the hydrophobic region of the liposome membrane. The liposomes with incorporated compounds are nanometric in size (diameter lower than 150 nm) and have generally low polydispersity.

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