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Meier AR, Yehl JB, Eckenroad KW, Manley GA, Strein TG, Rovnyak D. Stepwise Aggregation of Cholate and Deoxycholate Dictates the Formation and Loss of Surface-Available Chirally Selective Binding Sites. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6489-6501. [PMID: 29733655 DOI: 10.1021/acs.langmuir.8b00467] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bile salts are facially amphiphilic, naturally occurring chemicals that aggregate to perform numerous biochemical processes. Because of their unique intermolecular properties, bile salts have also been employed as functional materials in medicine and separation science (e.g., drug delivery, chiral solubilization, purification of single-walled carbon nanotubes). Bile micelle formation is structurally complex, and it remains a topic of considerable study. Here, the exposed functionalities on the surface of cholate and deoxycholate micelles are shown to vary from one another and with the micelle aggregation state. Collectively, data from NMR and capillary electrophoresis reveal preliminary, primary, and secondary stepwise aggregation of the salts of cholic (CA) and deoxycholic (DC) acid in basic conditions (pH 12, 298 K), and address how the surface availability of chirally selective binding sites is dependent on these sequential stages of aggregation. Prior work has demonstrated sequential CA aggregation (pH 12, 298 K) including a preliminary CMC at ca. 7 mM (no chiral selection), followed by a primary CMC at ca. 14 mM that allows chiral selection of binaphthyl enantiomers. In this work, DC is also shown to form stepwise preliminary and primary aggregates (ca. 3 mM DC and 9 mM DC, respectively, pH 12, 298 K) but the preliminary 3 mM DC aggregate is capable of chirally selective solubilization of the binaphthyl enantiomers. Higher-order, secondary bile aggregates of each of CA and DC show significantly degraded chiral selectivity. Diffusion NMR reveals that secondary micelles of CA exclude the BNDHP guests, while secondary micelles of DC accommodate guests, but with a loss of chiral selectivity. These data lead to the hypothesis that secondary aggregates of DC have an exposed binding site, possibly the 7α-edge of a bile dimeric unit, while secondary CA micelles do not present binding edges to the solution, potentially instead exposing the three alcohol groups on the hydrophilic α-face to the solution.
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Affiliation(s)
- Adam R Meier
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
| | - Jenna B Yehl
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
| | - Kyle W Eckenroad
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
| | - Gregory A Manley
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
| | - Timothy G Strein
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
| | - David Rovnyak
- Department of Chemistry , Bucknell University , 1 Dent Drive , Lewisburg , Pennsylvania 17837 , United States
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Gubitosi M, Meijide F, D'Annibale A, Vázquez Tato J, Jover A, Galantini L, Travaglini L, di Gregorio MC, Pavel NV. Crystal structure of a lithium salt of a glucosyl derivative of lithocholic acid. Steroids 2016; 113:87-94. [PMID: 27394960 DOI: 10.1016/j.steroids.2016.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 06/01/2016] [Accepted: 07/04/2016] [Indexed: 11/30/2022]
Abstract
The crystal structure of a Li(+) salt of a glucosyl derivative of lithocholic acid (lithium 3α-(α-d-glucopyranosyl)-5β-cholan-24-oate) has been solved. The crystal belongs to the orthorhombic system, P212121 spatial group, and includes acetone and water in the structure with a 1:1:2 stoichiometry. Monolayers, having a hydrophobic interior and hydrophilic edges, are recognized in the crystal structure. Li(+) is coordinated to three hydroxyl groups of three different glucose residues, with two of them belonging to the same monolayer. A fourth molecule, located in this monolayer, is involved in the coordination of the cation through the carboxylate ion by an electrostatic interaction, thus completing a distorted tetrahedron. All Li(+)-oxygen distances values are very close to the sum of the ionic radius of Li(+) and van der Waals radius of oxygen. Each steroid molecule is linked to other five steroid molecules through hydrogen bonds. Water and acetone are also involved in the hydrogen bond network. A hierarchical organization can be recognized in the crystal, the helical assembly along 21 screw axes being left-handed.
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Affiliation(s)
- Marta Gubitosi
- Dipartimento di Chimica, Università di Roma "La Sapienza", P. le A. Moro 5, 00185 Roma, Italy
| | - Francisco Meijide
- Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain.
| | - Andrea D'Annibale
- Dipartimento di Chimica, Università di Roma "La Sapienza", P. le A. Moro 5, 00185 Roma, Italy
| | - José Vázquez Tato
- Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain
| | - Aida Jover
- Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain
| | - Luciano Galantini
- Dipartimento di Chimica, Università di Roma "La Sapienza", P. le A. Moro 5, 00185 Roma, Italy
| | - Leana Travaglini
- Dipartimento di Chimica, Università di Roma "La Sapienza", P. le A. Moro 5, 00185 Roma, Italy
| | | | - Nicolae V Pavel
- Dipartimento di Chimica, Università di Roma "La Sapienza", P. le A. Moro 5, 00185 Roma, Italy
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Anderson SL, Rovnyak D, Strein TG. Direct Measurement of the Thermodynamics of Chiral Recognition in Bile Salt Micelles. Chirality 2016; 28:290-8. [DOI: 10.1002/chir.22580] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 12/21/2015] [Accepted: 01/05/2015] [Indexed: 01/20/2023]
Affiliation(s)
- Shauna L. Anderson
- Department of Chemistry; Bucknell University; Lewisburg Pennsylvania USA
| | - David Rovnyak
- Department of Chemistry; Bucknell University; Lewisburg Pennsylvania USA
| | - Timothy G. Strein
- Department of Chemistry; Bucknell University; Lewisburg Pennsylvania USA
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Kabir-ud-Din, Al-dahbali GA, Naqvi AZ, Akram M. Adsorption and Micellization Behavior of Mixtures of Amphiphilic Drugs with Small Amounts of Bile Salts. TENSIDE SURFACT DET 2015. [DOI: 10.3139/113.110375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
AbstractBile acid salts are the most important biological surfactant-like molecules. These compounds play an active role in the cholesterol and lipid solubilization. They are also used as drug carriers. The salts give anionic amphiphilic moiety in aqueous solution and will interact strongly when mixed with cationic amphiphiles. With this aim we have investigated mixed systems of three bile acid salts (sodium cholate (NaC), sodium deoxycholate (NaDC) and sodium taurocholate (NaTC)) with two cationic drugs (adiphenine hydrochloride (ADP) and clomipramine hydrochloride (CLP)) by surface tension measurements. It was found that the two components mix nonideally, i.e., the cmc values of the mixtures decrease with the stoichiometric mole fraction (α1) of bile salts and are lower than cmc* values (cmc at ideal mixing condition). The interaction parameters, βm and βσ, come out to be negative and large in magnitude which is obvious from the fact that the two components are of opposite charge and would experience attractive interactions. The results suggest that the contribution of bile salts in the mixed micelles (X1m) is greater than both the α1 and X1id (the contribution in ideal mixing condition). These components also form mixed interface where the contribution of bile salts is more than α1 (i.e., X1σ > α1). The minimum area occupied by a monomer decreases with increase in the content of bile salts in the solution. This confirms that the opposite charges on the two components decrease the repulsion among the head groups. All the evaluated thermodynamic parameters (i.e., ΔG0m, ΔGex, ΔG°ads and Gmin) support the above explanations.
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Chen Z, Wang J, Chen D, Fan G, Wu Y. Sodium desoxycholate-assisted capillary electrochromatography with methacrylate ester-based monolithic column on fast separation and determination of coumarin analogs in Angelica dahurica extract. Electrophoresis 2012; 33:2884-91. [PMID: 22930555 DOI: 10.1002/elps.201200120] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 05/11/2012] [Accepted: 05/14/2012] [Indexed: 11/11/2022]
Abstract
A rapid and sensitive CEC method with methacrylate ester-based monolithic column has been developed for separation and determination of five coumarins (byakangelicin, oxypeucedanin hydrate, xanthotoxol, 5-hydroxy-8-methoxypsoralen and bergapten) in Angelica dahurica extract. Surfactant sodium desoxycholate (SDC) was introduced into the mobile phase as the pseudostationary to dynamically increase the selectivity of analytes instead of increasing the hydrophobicity of stationary phase. In addition, other factors, pH of phosphate buffer, ACN content and applied voltage, for instance, have also an obvious effect on the resolution but little on the retention time. Satisfactory separation of these five coumarins was achieved within 6 min under a 30:70 v/v ACN-buffer containing 20 mM sodium dihydrogen phosphate (NaH(2) PO(4) ) and 0.25 mM SDC at pH 2.51. The RSDs of intraday and interday for relative peak areas were less than 3.0% and 4.7%, respectively; and the recoveries were between 87.5% and 95.0%. The LODs were lower than 0.15 μg/mL and the LOQs were lower than 0.30 μg/mL, respectively, while calibration curves showed a good linearity (r(2) > 0.9979). Finally, five target coumarins from the crude extracts of A. dahurica were separated, purified, and concentrated by D-101 macroporous resin, and were successfully separated and quantitatively determined within 6 min.
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Affiliation(s)
- Zhao Chen
- Department of Pharmaceutical Analysis, Second Military Medical University, Shanghai, People's Republic of China. cz04101103@ hotmail.com
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Bogdanova LR, Gnezdilov OI, Idiyatullin BZ, Kurbanov RK, Zuev YF, Us’yarov OG. Micellization in sodium deoxycholate solutions. COLLOID JOURNAL 2012. [DOI: 10.1134/s1061933x12010036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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de Petris G, Festa MR, Galantini L, Giglio E, Leggio C, Pavel NV, Troiani A. Sodium Glycodeoxycholate and Glycocholate Mixed Aggregates in Gas and Solution Phases. J Phys Chem B 2009; 113:7162-9. [DOI: 10.1021/jp9010586] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Giulia de Petris
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Maria Rosa Festa
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Luciano Galantini
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Edoardo Giglio
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Claudia Leggio
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Nicolae Viorel Pavel
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Anna Troiani
- Dipartimento di Chimica, Research Center SOFT-INFM-CNR, and Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
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Bremer S, Trapp O. Investigation of the stereodynamics of tris-(α-diimine)-transition metal complexes by enantioselective dynamic MEKC. Electrophoresis 2009; 30:329-36. [DOI: 10.1002/elps.200800320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Aggregation behavior of sodium deoxycholate and its interaction with cetyltrimethylammonium bromide in aqueous solution studied by NMR spectroscopy. Colloid Polym Sci 2008. [DOI: 10.1007/s00396-008-1938-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Amundson LL, Li R, Bohne C. Effect of the guest size and shape on its binding dynamics with sodium cholate aggregates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8491-500. [PMID: 18637697 DOI: 10.1021/la800439m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The binding dynamics of the guests acenaphthene, phenanthrene, fluorene, and acenaphthenol with sodium cholate aggregates were studied using laser flash photolysis and fluorescence. The location of the guests in the bile salt aggregate is determined by the guest's hydrophobicity, where acenaphthene, phenanthrene, and fluorene bind to the primary aggregates, while acenaphthenol binds to the secondary bile salt aggregates. The residence time of the guests in the primary aggregates and the access of ionic species from the aqueous phase to the guest in the aggregate depend on the size and the shape of the guest. These results show that bile salt aggregates are adaptable supramolecular host systems.
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Affiliation(s)
- Laurie L Amundson
- Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC, Canada
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Youssry M, Coppola L, Furia E, Oliviero C, Nicotera I. A new physicochemical characterization of sodium taurodeoxycholate/water system. Phys Chem Chem Phys 2008; 10:6880-9. [DOI: 10.1039/b809582e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Calabresi M, Andreozzi P, La Mesa C. Supra-molecular association and polymorphic behaviour in systems containing bile acid salts. Molecules 2007; 12:1731-54. [PMID: 17960084 DOI: 10.3390/12081731] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 07/12/2007] [Accepted: 07/12/2007] [Indexed: 11/16/2022] Open
Abstract
A wide number of supra-molecular association modes are observed in mixtures containing water and bile salts, BS, (with, eventually, other components). Molecular or micellar solutions transform into hydrated solids, fibres, lyotropic liquid crystals and/or gels by raising the concentration, the temperature, adding electrolytes, surfactants, lipids and proteins. Amorphous or ordered phases may be formed accordingly. The forces responsible for this very rich polymorphism presumably arise from the unusual combination of electrostatic, hydrophobic and hydrogen-bond contributions to the system stability, with subsequent control of the supra-molecular organisation modes. The stabilising effect due to hydrogen bonds does not occur in almost all surfactants or lipids and is peculiar to bile acids and salts. Some supra-molecular organisation modes, supposed to be related to malfunctions and dis-metabolic diseases in vivo, are briefly reported and discussed.
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Affiliation(s)
- Marco Calabresi
- Dipartimento di Chimica and SOFT-INFM-CNR Research Centre, Università La Sapienza, P.le A. Moro 5, Roma, I-00185, Italy
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14
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Trapp O. A dynamic molecular probe to investigate catalytic effects and Joule heating in enantioselective MEKC. Electrophoresis 2007; 28:691-6. [PMID: 17226759 DOI: 10.1002/elps.200600596] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Enantiomerization of ferroin [tris(1,10-phenanthroline)-iron(II)-complex] was investigated by enantioselective dynamic micellar EKC. The enantiomer separation was performed in an aqueous 50 mM sodium borate/sodium dihydrogenphosphate buffer at pH 8.0 in the presence of the chiral surfactant sodium cholate. The unified equation of dynamic chromatography was employed to determine reaction rate constants from the electropherograms featured with distinct plateau formation. Activation parameters DeltaH( not equal) = 124.0 +/- 0.5 kJ/mol and DeltaS( not equal) = 121 +/- 1 J.K(-1)mol(-1) were calculated from temperature-dependent measurements between 10.0 and 27.5 degrees C in 2.5 K steps. Considering the data obtained by polarimetry of enantiomeric pure ferroin in water, it was found that enantiomerization rate in the micelle is accelerated by a factor of 12. Because of the highly positive activation entropy DeltaS( not equal), ferroin was used as a temperature-sensitive dynamic molecular probe to determine temperature deviations caused by Joule heating.
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Affiliation(s)
- Oliver Trapp
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
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15
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Orioni B, Roversi M, La Mesa C, Asaro F, Pellizer G, D'Errico G. Polymorphic Behavior in Protein−Surfactant Mixtures: The Water−Bovine Serum Albumin−Sodium Taurodeoxycholate System. J Phys Chem B 2006; 110:12129-40. [PMID: 16800527 DOI: 10.1021/jp055950r] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mixtures containing water, bovine serum albumin (BSA), and sodium taurodeoxycholate (NaTDC), a component of the bile in mammals, have been investigated in a wide range of composition and pH. Depending on the concentration of both solutes and the pH, solutions, precipitates, and gels are formed. Under spontaneous pH conditions, the transport properties in dilute solutions indicate the occurrence of significant interactions between BSA and the surfactant. Conversely, acidic media favor the formation of nonsoluble protein-surfactant complexes, with subsequent precipitation. The nucleation kinetics of the protein-surfactant complexes in solid form and the related precipitation processes can be slow or fast, depending on the overall solute content and the mole ratio. At high concentrations, a gel, extending on both sides of the charge neutralization line, and two-phase regions are observed. Gels shrink in open air and swell in the presence of excess water. Depending on concentration and temperature, the gels transform from an essentially liquidlike behavior to that peculiar to true gels (when G' > or = G''). The thermal gelation threshold, the temperature above which G' > or = G'', depends on BSA and NaTDC content and is concomitant to moderate heat effects, inferred by differential scanning calorimetry (DSC). The above data also indicate that the protein thermal denaturation in the gel is shifted to higher temperatures compared to water. Such a stabilizing effect is presumably related to the occurrence of both electrostatic and hydrophobic interactions with NaTDC. Water self-diffusion in the gels is slightly slower than that in the bulk and poorly sensitive to composition: it is about 65% the value of neat H2O in a wide concentration range, irrespective of the BSA, or NaTDC, concentration. A peculiar behavior is also observed in 23Na longitudinal and transverse relaxation rates. The T1 and T2 values, measured at 105.75 MHz on BSA-NaTDC gels, indicate that the motions determining the NMR relaxation of the sodium ions in the hydration layer of the protein-surfactant aggregates are not slow, having frequencies comparable with the Larmor one. The above properties, especially the rheological and the spectroscopic ones, are important for understanding the behavior of gels based on protein-surfactant mixtures.
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Affiliation(s)
- Barbara Orioni
- Dipartimento di Chimica and SOFT-INFM-CNR Research Center, Università La Sapienza, P.le A. Moro 5, 00185 Roma, Italy
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Waissbluth OL, Morales MC, Bohne C. Influence of Planarity and Size on Guest Binding with Sodium Cholate Aggregates. Photochem Photobiol 2006; 82:1030-8. [PMID: 16555923 DOI: 10.1562/2006-02-14-ra-803] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bile salt aggregates are supramolecular structures with two types of binding sites, called primary and secondary sites. The objective of this work was to explore how the nonplanarity and size of guests (biphenyl [BP], 1-1'-binaphthyl [BNP] and dibenz[b,f]oxepin [DBX]) affected their binding affinity and dynamics to sodium cholate (NaC) aggregates. Fluorescence and laser-flash photolysis experiments were performed to obtain information on the binding environment for the guests, the accessibility of quenchers to guests in the aggregate and the dissociation rate constants of the guests from the aggregates. All guests were bound to the more hydrophobic primary aggregate, showing that this site can accommodate nonplanar molecules. However, the structure of the guest affects the structure of the primary aggregates, leading to changes in the accessibility of anions to aggregate-bound guests and to changes for the guest dissociation rate constants from the aggregates.
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Terech P, Sangeetha NM, Demé B, Maitra U. Self-Assembled Networks of Ribbons in Molecular Hydrogels of Cationic Deoxycholic Acid Analogues. J Phys Chem B 2005; 109:12270-6. [PMID: 16852514 DOI: 10.1021/jp050666l] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aqueous gels derived from three cationic 24-nor 3,12-dihydroxy cholane (DC) derivatives with N-methyl-2-pyrrolidinone (NMP), N-methylmorpholine (NMM), and 1,4-diazabicyclo[2.2.2]octane (DABCO) at the side chain positions have been exhaustively characterized by small-angle neutron-scattering experiments. Although the molecular structures differ slightly by the heterocycle grafted to the steroid core, the derived gels exhibit a range of structural behaviors at the nanoscale that depart from those observed with simple deoxycholate systems. The NMM-DC aggregates are ribbons with a bimolecular thickness of t = 37 A and an anisotropy of the section b/a approximately 0.1. DABCO-DC exhibits a remarkable transition from ribbons (t = 29.5 A, b/a = 0.18) to thicker cylindrical fibers (R approximately 59 A), involving four original ribbons, upon a concentration increase. The NMP-DC system forms thick cylindrical fibers (R approximately 68 A) with steroid molecules organized in a specific morphology. Bilayered or interdigited structures are formed and favored by the presence of multiple polar interaction centers in the DC molecules. Secondary aggregation mechanisms are invoked in the formation of bundles having a lower cross-sectional anisotropic symmetry and exhibiting Bragg peaks corresponding to molecular length periodicities. The relations between the structural information and the rheological properties are discussed.
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Affiliation(s)
- Pierre Terech
- UMR5819, CEA-CNRS, Université J. Fourier, DRFMC-SI3M, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble, Cedex 9, France.
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Rinco O, Nolet MC, Ovans R, Bohne C. Probing the binding dynamics to sodium cholate aggregates using naphthalene derivatives as guests. Photochem Photobiol Sci 2005; 2:1140-51. [PMID: 14690227 DOI: 10.1039/b308335g] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The binding dynamics with bile salt aggregates for a series of naphthalene derivatives of different polarities was studied using fluorescence and laser flash photolysis. Fluorescence was employed to determine the nature of the binding site for each guest and the accessibility of the bound guest to quenchers. Laser flash photolysis was employed to study the mobility of the triplet states of the naphthalenes between the sodium cholate aggregates and the aqueous phase. Primary aggregates, which provide an environment protected from quenchers in the aqueous phase, bind 1- and 2-ethylnaphthalene as guests. The complexation dynamics with this type of aggregate is slow. 1- and 2-Naphthyl-1-ethanol, and 1- and 2-acetonaphthone bind to the secondary aggregates, which provide moderate protection from quenching and faster binding dynamics. The addition of salts lowered the cholate concentration at which primary aggregates were formed, but did not influence the formation of secondary aggregates.
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Affiliation(s)
- Olga Rinco
- Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC, Canada V8W 3V6
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Galantini L, Giglio E, Pavel NV, Punzo F. QELS and X-ray study of two dihydroxy bile salt aqueous solutions. Colloids Surf A Physicochem Eng Asp 2004. [DOI: 10.1016/j.colsurfa.2004.06.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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20
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Amenitsch H, Edlund H, Khan A, Marques E, La Mesa C. Bile salts form lyotropic liquid crystals. Colloids Surf A Physicochem Eng Asp 2003. [DOI: 10.1016/s0927-7757(02)00360-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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Zhang SZ, Xie JW, Liu CS. Microenvironmental properties and chiral discrimination abilities of bile salt micelles by fluorescence probe technique. Anal Chem 2003; 75:91-7. [PMID: 12530823 DOI: 10.1021/ac020373d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The microenvironmental properties as well as the chiral discrimination abilities of four kinds of bile salt micelles were investigated by the fluorescence probe technique. A new fluorescence probe, 1,1'-bi-2-naphthol, was exploited to study the aggregation of bile salts, size, micropolarity, and microrigidity of the micelles with or without the presence of inorganic salts. Based on these results, the chiral discrimination abilities of bile salt micelles were further investigated by using (R)- and (S)-1,1'-bi-2-naphthol as chiral fluorescence probes. Different chiral discrimination ability was revealed by fluorescence spectra, fluorescence increase rate, and fluorescence quenching constants. The chiral discrimination mechanism of bile salt micelles was discussed.
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Affiliation(s)
- Shu-Zhen Zhang
- Beijing Institute of Pharmacology and Toxicology, Beijing, P.R. China
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Bielejewska A, Duszczyk K, Kwaterczak A, Sybilska D. Comparative study on the enantiomer separation of 1,1'-binaphthyl-2,2'diyl hydrogenphosphate and 1,1'-bi-2-naphthol by liquid chromatography and capillary electrophoresis using single and combined chiral selector systems. J Chromatogr A 2002; 977:225-37. [PMID: 12456112 DOI: 10.1016/s0021-9673(02)01389-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The chiral recognition ability of single and dual selectors, that were used as additives, have been investigated by HPLC and CE. Native beta- and gamma-cyclodextrins, permethylated beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin, cholic acid and taurodeoxycholic acid sodium salts were applied as chiral selectors, whereas the atropisomers of 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate, and 1,1'-bi-2-naphthol served as model compounds. It was found that all investigated selectors, except for gamma-cyclodextrin, display the same affinity pattern for binaphthyl enantiomers, i.e., binding the S more strongly than the R enantiomer. However, the differences in the phase distribution of chiral selectors led to the opposit elution order of enantiomers: with cyclodextrins, the first eluted is S enantiomer, while R is the first eluted for bile salts. Under the conditions studied, cyclodextrins (except gamma-cyclodextrin), as well as cholic acid sodium salts acting singly, enable the separation of 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate enantiomers both by HPLC and CE methods, while 1,1'-bi-2-naphthol enantiomers were resolved only under CE conditions with permethylated cyclodextrin or bile salts. In both techniques the application of dual systems could improve resolution or make it worse (oreven cancel), depending on the sign of enantioselectivity of particular selectors, their concentrations and localization: mobile or stationary phase. It has been found that the mechanism of separation as well as interactions occurring between two selectors may be followed by using combined HPLC and CE methods. The obtained results proved that, as well as beta-CD, TM-beta-D and gamma-CD also form inclusion complexes with cholic acid sodium salts. The reversal of elution order may be realized by two procedures: changing a single selector, i.e., cyclodextrin on cholic acid sodium salt or vice versa, and by changing the proportion of selectors in the combined bile salt-cyclodextrin system.
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Affiliation(s)
- Anna Bielejewska
- Institute of Physical Chemistry of the Polish Academy of Sciences, Kasprzaka 44.52, 01-224 Warsaw, Poland
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23
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Elshihabi S, Black KD, Sutton JK, Woody KA, Burke JA, Bushey MM. Micellar electrokinetic chromatography of tri aza aromatic ligand compounds of iron (II): influence of bile salt type on enantiomeric separation. Electrophoresis 2001; 22:3771-7. [PMID: 11699917 DOI: 10.1002/1522-2683(200109)22:17<3771::aid-elps3771>3.0.co;2-j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Micellar electrokinetic chromatography is used with a variety of bile salt micelles to separate the enantiomers of bis(8-((pyridine-2-methylene)amino)quinoline)iron(II) hexafluorophosphate, Fe(PMAQ)2(PF6)2; bis(8-((pyridine-2-methylene)amino)lepidine iron(II) hexafluorophosphate, Fe(PMAL)2(PF6)2; and bis(1-(2-pyridinyl)ethylidine)-8-aminoquinoline iron(II) hexafluorophosphate, Fe(PEAQ)2(PF6)2. The influence of ten different bile salts on the resolution of each pair of enantiomers is investigated. Significant changes in resolution are seen depending upon the bile salt used. The dihydroxy bile salts are superior to the trihydroxy bile salts in terms of resolution, and the taurine or glycine conjugated bile salts yield better results than the unconjugated bile salts. Resolution for most enantiomers is maximized in a buffer solution containing 10-15% acetone and employing either taurochenodeoxycholic or glycochenodeoxycholic acid as the bile salt. Evidence for the separation of the corresponding Fe(III) complexes is presented.
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Affiliation(s)
- S Elshihabi
- Department of Chemistry, Trinity University, San Antonio, TX 78212, USA
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24
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Herrero-Martínez JM, Fernández-Martí M, Simó-Alfonso E, Ramis-Ramos G. Determination of alkylphenol ethoxylates by micellar electrokinetic chromatography with bile salts. Electrophoresis 2001; 22:526-34. [PMID: 11258765 DOI: 10.1002/1522-2683(200102)22:3<526::aid-elps526>3.0.co;2-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Octyl- and nonylphenol ethoxylates (OPEs and NPEs) with different numbers of ethoxy units (average values: n = 10 and N = 40 for OPEs, and n = 10 for NPEs) were separated by micellar electrokinetic chromatography under positive polarity using an 80 mM borate buffer of pH 8.5 containing sodium deoxycholate (SDC) or sodium cholate (SC). When sodium dodecyl sulfate (SDS) was added to the background electrolyte (BGE) in the absence of the bile salt, a single peak at a migration time longer than that of the EOF was obtained. Substituting the SDS by a bile salt, the homologues were resolved. At the same bile salt concentration, resolution between the homologues was higher with SDC than using SC. Optimum resolution between consecutive homologues was obtained with 50 mM SDC. In the presence of low or moderate amounts of acetonitrile or n-propanol, the background line improved significantly, whereas resolution may increase or decrease slightly. We propose a procedure for the determination of OPEs and NPEs with optimum resolution between the homologues as well as a modified procedure with improved selectivity for the single-run determination of other absorbing nonionic, cationic, and anionic (such as linear alkylbenzene sulfonates) surfactants in industrial and household cleaning products and its application to a variety of samples. The detection limit was ca. 28 microg x mL(-1) of total NPE (n = 10), and peak area repeatabilities at 50 microg x mL(-1) were 1.7% (intraday) and 5.6% (interday).
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Affiliation(s)
- J M Herrero-Martínez
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Burjassot, Spain
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25
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Herrero-Martínez JM, Simó-Alfonso EF, Mongay-Fernández C, Ramis-Ramos G. Determination of cationic surfactants by capillary zone electrophoresis and micellar electrokinetic chromatography with deoxycholate micelles in the presence of large organic solvent concentrations. J Chromatogr A 2000; 895:227-35. [PMID: 11105866 DOI: 10.1016/s0021-9673(00)00592-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mixtures of the cationic surfactants benzalkonium chloride (BKC) and cetylpyridinium chloride (CPC) were quickly resolved and reproducibly and reliably determined by using background electrolytes (BGEs) containing 80 mM borate, pH 8.5, bile salts and large concentrations of an organic solvent. When the bile salt is present, the separation mechanism changes from capillary zone electrophoresis (CZE) to a mixed micellar electrokinetic chromatography (MEKC)-CZE, with predominant MEKC interactions, which lead to an excellent resolution of all the solutes, including the C12-C18 homologues of BKC and CPC. A BGE containing 50 mM sodium deoxycholate and 30% ethanol for an extreme resolution, or 20% tetrahydrofuran for an adequate resolution within a much shorter analysis time, is recommended. The procedure was applied to the determination of the surfactants in industrial and household formulations, with excellent resolution between the homologues, detection limits of a few microg ml(-1) and reproducibilities below 2%.
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Affiliation(s)
- J M Herrero-Martínez
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Burjassot, Spain
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26
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Otsuka K, Terabe S. Enantiomer separation of drugs by micellar electrokinetic chromatography using chiral surfactants. J Chromatogr A 2000; 875:163-78. [PMID: 10839143 DOI: 10.1016/s0021-9673(99)01167-x] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A review surveying enantiomer separations by micellar electrokinetic chromatography (MEKC) using chiral surfactants is described. MEKC is one of the most popular techniques in capillary electrophoresis, where neutral compounds can be analyzed as well as charged ones, and the use of chiral micelles enable one to achieve the enantioseparation. The chiral MEKC systems are briefly reviewed according to the types of chiral surfactants along with typical applications. As chiral micelles or pseudostationary phases in MEKC, various natural and synthetic chiral surfactants are used, including several low-molecular-mass surfactants and polymerized surfactants or high-molecular-mass surfactants. Cyclodextrin modified MEKC using chiral micelles is also considered.
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Affiliation(s)
- K Otsuka
- Department of Material Science, Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo, Japan.
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27
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Maeder C, Beaudoin GM, Hsu E, Escobar VA, Chambers SM, Kurtin WE, Bushey MM. Measurement of bilirubin partition coefficients in bile salt micelle/aqueous buffer solutions by micellar electrokinetic chromatography. Electrophoresis 2000; 21:706-14. [PMID: 10733210 DOI: 10.1002/(sici)1522-2683(20000301)21:4<706::aid-elps706>3.0.co;2-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The partition coefficients for the distribution of bilirubin between aqueous phosphateborate buffer and cholic, taurocholic, taurodeoxycholic, and taurochenodeoxycholic micelles have been measured by micellar electrokinetic chromatography at pH 8.5. Determination of the partition coefficients required that the critical micelle concentration and partial specific volumes be determined for each bile salt. Critical micelle concentrations were slightly higher for the trihydroxy bile salts. Partial specific volumes of the bile salt micelles differed very little from each other, and for each bile salt they were constant over the concentration range studied, which was typically from slightly above the critical micelle concentration to 35 mM. Capacity factors were corrected for the effects of applied voltage by extrapolation of the capacity factor to zero applied volts. The free solution mobility of bilirubin, determined in the absence of bile salt, was also corrected for the effects of applied voltage. Plots of extrapolated capacity factor versus phase ratio yield the partition coefficient as the slope of a linear fit to the data. Partition coefficients for bilirubin were significantly higher for dihydroxy bile salts than for trihydroxy bile salts.
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Affiliation(s)
- C Maeder
- Department of Chemistry, Trinity University, San Antonio, TX 78212, USA
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28
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Lin JM, Nakagawa M, Uchiyama K, Hobo T. Determination of critical micelle concentration of SDS in formamide by capillary electrophoresis. Chromatographia 1999. [DOI: 10.1007/bf02497314] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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29
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Bonincontro A, D'Archivi AA, Galantini L, Giglio E, Punzo F. On the Micellar Aggregates of Alkali Metal Salts of Deoxycholic Acid. J Phys Chem B 1999. [DOI: 10.1021/jp990278h] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Adalberto Bonincontro
- INFM, Dipartimento di Fisica, Università di Roma “La Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
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30
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Abstract
This review presents the different chiral selectors used in capillary electrophoresis (CE) for the separation of enantiomers. The use of charged cyclodextrins, crown ethers, polysaccharides, proteins, natural and synthetic micelles, macrocyclic antibiotics and ergot alkaloids is discussed in detail. Neutral native and derivatized cyclodextrins are not treated because several review articles have already been published on this topic. Recent developments like the application of two chiral selectors in the same background electrolyte are highlighted.
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Affiliation(s)
- K Verleysen
- Department of Organic Chemistry, University of Gent, Belgium
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31
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Crego AL, Gonzalez MJ, Marina ML. Chiral separation of polychlorinated biphenyls by micellar electrokinetic chromatography with sodium cholate. Electrophoresis 1998; 19:2113-8. [PMID: 9761190 DOI: 10.1002/elps.1150191212] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Micellar electrokinetic chromatography (MEKC) with one kind of bile salt (sodium cholate) was used to separate three chiral polychlorinated biphenyls (PCBs; 84, 95, and 176), each one in its two enantiomers. Sodium cholate was used as chiral surfactant in a 2-(N-cyclohexylamino) ethanesulfonic acid (CHES) buffer under alkaline (pH 10) conditions containing urea (2 M). The influence of bile salt concentration on the efficiency and the resolution between the two enantiomers of PCBs 84 and 95 was established. The chiral separation of three PCBs was successfully achieved in less than 30 min (approximately 23 min for PCB 176 and approximately 29 min for PCBs 84 and 95).
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Affiliation(s)
- A L Crego
- Departamento de Química Analítica, Facultad de Ciencias, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain.
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32
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Goswami A, Pal MK. Spectroscopic probes of the interactions of the dye Stains-all with deoxycholate and cholate. Colloids Surf B Biointerfaces 1998. [DOI: 10.1016/s0927-7765(97)00057-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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33
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34
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Bonincontro A, Briganti G, D'Archivio AA, Galantini L, Giglio E. Structural Study of the Micellar Aggregates of Sodium Taurodeoxycholate. J Phys Chem B 1997. [DOI: 10.1021/jp964004v] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Micelles as separation media in high-performance liquid chromatography and high-performance capillary electrophoresis: overview and perspective. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(97)00610-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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36
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Dobashi A, Hamada M. Molecular recognition with micellar and micelle-like aggregates in aqueous media. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(97)00546-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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37
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Nittler MP, Desai RA, Salikof DA, Kurtin WE, Bushey MM. Bile salt micellar electrokinetic chromatography of bilirubin and related compounds. J Chromatogr A 1997; 779:205-14. [PMID: 9335123 DOI: 10.1016/s0021-9673(97)00426-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The interaction of bilirubin, biliverdin, bilirubin dimethyl ester, biliverdin dimethyl ester, xanthobilirubic acid, and xanthobilirubin methyl ester with trihydroxy and dihydroxy bile salt solutions is investigated by micellar electrokinetic chromatography (MEKC). The capacity factor of each compound is measured in solutions of the different bile salts over the pH range of 6.5-9.0. The capacity factor of bilirubin increases with pH below 7 in all bile salt solutions. Biliverdin and xanthobilirubin show essentially identical capacity factors for all bile salts. Biliverdin dimethyl ester and xanthobilirubin methyl ester also have very similar capacity factors, which are greater than those of the carboxy analogs, in trihydroxy bile salts. The capacity factors of these esters are higher in the dihydroxy bile salts, with the capacity factor of biliverdin dimethyl ester being twice that of xanthobilirubin methyl ester. Factors involved in the MEKC analysis of these compounds are discussed.
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Affiliation(s)
- M P Nittler
- Department of Chemistry, Trinity University, San Antonio, TX 78212, USA
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38
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Shamsi SA, Warner IM. Monomeric and polymeric chiral surfactants as pseudo-stationary phases for chiral separations. Electrophoresis 1997; 18:853-72. [PMID: 9221871 DOI: 10.1002/elps.1150180604] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- S A Shamsi
- Department of Chemistry, Louisiana State University, Baton Rouge 70803, USA
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39
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Bumgarner JG, Khaledi MG. Mixed micelles of short chain alkyl surfactants and bile salts in electrokinetic chromatography: enhanced separation of corticosteroids. J Chromatogr A 1996; 738:275-83. [PMID: 8696507 DOI: 10.1016/0021-9673(96)00081-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The separation of a complex mixture of 17 corticosteroids was investigated by mixed micellar electrokinetic chromatography (MMEKC) employing various bile salts and/or alkylsulfonates. In this study, influence of individual surfactants and mixed micelles of hydrocarbon-bile salt surfactants on retention behavior, selectivity and the size of the elution window is investigated. Retention behavior of corticosteroids in SDS and bile salt micelles is examined using linear solvation energy relationships (LSER). In addition, the effects of type of bile salt surfactant on elution patterns were investigated. It was found that separation patterns are mostly influenced by the number of hydroxyl functional groups on the steroidal backbone of the bile salts, while the type of ionic head group has little, if any, effect on the steroids separation. Comparisons between mixed micellar techniques and the inclusion of conventional modifiers to various single and binary surfactant systems were made. The addition of modifiers such as acetonitrile, urea and beta-cyclodextrin to SDS surfactant systems, as well as mixed bile salt systems of sodium taurocholate and sodium glycodeoxycholate, did not improve the separation of the steroids. On the other hand, the addition of the short-chain alkylsulfonate sodium butanesulfonate to the mixture of taurocholate and glycodeoxycholate greatly improved the separation of the 17 corticosteroids and provided a baseline separation of all solutes. The effects of carbon chain length and concentration of alkylsulfonate on capacity factor, selectivity, efficiency and the size of the elution window were investigated.
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Affiliation(s)
- J G Bumgarner
- Department of Chemistry, North Carolina State University, Raleigh 27695-8204, USA
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40
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Enantiomeric separation of local anaesthetic drugs by micellar electrokinetic capillary chromatography with taurodeoxycholate as chiral selector. J Chromatogr A 1996. [DOI: 10.1016/0021-9673(95)01195-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Abstract
This review surveys the enantiomer separation of drugs by electrokinetic chromatography (EKC). EKC is one option of capillary electrophoretic (CE) techniques, which permits the separation of electrically neutral drugs. In enantiomer separation by EKC, ionic pseudo-stationary phases such as chiral micelles and proteins, which can migrate with its electrophoretic mobility and can interact with the solutes, are employed as chiral selectors. Addition of electrically neutral chiral selectors such as cyclodextrins and precolumn conversion of solutes into diastereomers are also successful in EKC. A brief theory of separation and modes of EKC enantiomer separation are described with some typical applications.
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Affiliation(s)
- H Nishi
- Analytical Research Laboratory, Tanabe Seiyaku Co., Ltd., Osaka, Japan
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42
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43
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Beijersten I, Westerlund D. Capillary zone electrophoresis and micellar electrokinetic chromatography, with taurodeoxycholate as micellar agent, of protein kinase A peptide substrates. Electrophoresis 1996; 17:161-7. [PMID: 8907534 DOI: 10.1002/elps.1150170126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The separation of protein kinase A peptide substrates with the general formula -X-Arg-Arg-Ala-Ser-Y-, where X and Y may be the same or different amino acids, was studied by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Taurodeoxycholate (TDC) was used as the micellar agent. CZE was effective in separating a peptide series differing in the number of amino acids, but not for a series with a difference in the terminating amino acid. For the latter series, MEKC generally gave a higher selectivity, but some of the peptide pairs were more easily separated by CZE, demonstrating the complementary character of the two techniques. The efficiency of the MEKC system was typically < 50% of that of CZE, but its higher selectivity generally outbalanced the lower efficiency regarding resolution. The distribution of the peptides to the micelles was studied by determination of retention factors. Electrostatic and hydrophobic forces were found to be determining factors in the distribution; the most highly charged basic peptides were most heavily distributed, and for peptides with the same charge those containing more hydrophobic amino acids were more strongly distributed. The contribution of some structural features to the distribution degree was also determined.
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Affiliation(s)
- I Beijersten
- Analytical Pharmaceutical Chemistry, Faculty of Pharmacy, Uppsala University, Sweden
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44
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See MM, Elshihabi S, Burke JA, Bushey MM. Resolution effects of organic additives on the MEKC enantiomeric separations of tri aza aromatic ligand compounds of iron(II). ACTA ACUST UNITED AC 1995. [DOI: 10.1002/mcs.1220070303] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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45
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46
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Aumatell A, Wells RJ. Enantiomeric differentiation of a wide range of pharmacologically active substances by cyclodextrin-modified micellar electrokinetic capillary chromatography using a bile salt. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)00885-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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47
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Bjergegaard C, Simonsen H, Sørensen H. Determination of heterocyclic compounds by micellar electrokinetic capillary chromatography. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)85155-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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48
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Abstract
Mixed micellar electrokinetic chromatography (MMEKC) using mixtures of bile salt surfactants and/or sodium dodecyl sulfate (SDS) was employed to separate a group of corticosteroids. Resolution of electrokinetic chromatography (EKC) can be greatly enhanced by the use of mixed micellar systems due to the fact that the composition of the mixed micelles has a great influence on retention, selectivity and the size of the elution window. By combining surfactants with different structural properties, solute-micelle interactions were manipulated in order to elicit specific separations. Various combinations of bile salts and/or SDS at different mole fractions as well as total micelle concentrations were used in order to enhance the resolution of corticosteroid separations. Large changes in retention and selectivity were observed that often resulted in frequent variations in elution order. In addition, the composition of mixed micellar systems had a great influence on the elution window in EKC, as measured by the ratio of tmc/teo. Addition of SDS to the mixtures of bile salt micelles resulted in significant extension of the elution window and subsequently improvement in resolution. A separation of seventeen corticosteroids was achieved. Finally, MMEKC was applied in order to separate the steroidal components of a mixture of three anti-inflammatory creams.
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Affiliation(s)
- J G Bumgarner
- Department of Chemistry, North Carolina State University, Raleigh 27695-8204
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49
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Ostrow JD, Mukerjee P, Tiribelli C. Structure and binding of unconjugated bilirubin: relevance for physiological and pathophysiological function. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)39768-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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50
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Coello A, Meijide F, Rodríguez Núñez E, Vázquez Tato J. Aggregation behavior of sodium fusidate in aqueous solution. J Pharm Sci 1994; 83:828-32. [PMID: 9120815 DOI: 10.1002/jps.2600830614] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We analyzed the freezing point depression and pNa measurements for aqueous solutions of sodium fusidate. At concentrations lower than 0.011 mol kg(-1), sodium fusidate behaves as a strong 1:1 electrolyte. At higher concentrations, sodium fusidate self-aggregates. To analyze the results two hypotheses on the monomer concentration are presented and discussed. The first one accepts that the monomer concentration, C(A), is constant and equal to 0.023 mol kg(-1). This concentration corresponds to a break point in the plot of the freezing point depression vs total sodium fusidate concentration, C(A)t. The second hypothesis accepts that C(A) increases with C(A)t following a leveling-off curve. Measurements of hydrodynamic radii and comparison with similar systems, such as sodium taurocholate, strongly support the second hypothesis. The results indicate that at concentrations lower than 0.08 mol kg(-1) the aggregation number increases from 2 to 3. Above this concentration, both the aggregation number and the fraction of bound counterions remain constant, with average values of 3.13 +/- 0.10 and 0.31 +/- 0.05, respectively. Such results indicate that for trimers only one Na+ counterion is involved per aggregate. We propose that this counterion shields the repulsion between the two nearest carboxylate groups which, according to a disklike model in which the monomers are packed with that group alternatively oriented up and down, should hold together. Values for the formation equilibrium constant of aggregates are also calculated. Its dependence with the aggregation number allows the determination of the reversible transfer of a free surfactant ion together with the associated counterions from the bulk solution to the aggregate, the resulting value being w(0) = -4.2k(B)T.
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Affiliation(s)
- A Coello
- Universidade de Santiago, Campus de Lugo, Facultade de Ciencias, Departamentos de Química Física e Física Aplicada, Spain
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