Solubilization of food bioactives within lyotropic liquid crystalline mesophases

Liquid crystals are widely utilized as model systems to mimic biological processes where the phase behavior of lipids plays a mediating role. In various foods and pharmaceutical and biotechnical applications, the liquid crystalline phases formed by surfactants in an aqueous medium represent useful host systems for drugs, amino acids, peptides, proteins and vitamins.Various biologically active food additives are soluble in neither aqueous nor oil phase and require environmental protection against hydrolysis or oxidation. Lyotropic liquid crystals meet these requirements mainly due to their high solubilization capacities for hydrophilic, lipophilic and amphiphilic guest molecules. Moreover, recent studies demonstrated controlled and/or sustained release of solubilized molecules from different liquid crystalline matrices.This paper surveys the solubilization of hydrophilic, lipophilic and amphiphilic guest molecules for food applications and illustrates the corresponding structural transformations. Recent developments in liquid crystal characterization methods are discussed.     

The dependence on temperature and concentration of 129Xe NMR chemical shift values of organoxenon(II) salts [RXe][Y] and of the parent molecule XeF2

The dependence of the 129Xe NMR chemical shift value of XeF2 on temperature and concentration was determined in a variety of prototypic media: in acidic (anhydrous HF, aHF), nonprotic but polar (dichloromethane), and basic (CD3CN-EtCN, 1:3 v/v) solvents. The 129Xe NMR spectra of a representative series of organoxenon(II) salts [RXe][Y] (R = C6F5, heptafluoro-1,4-cyclohexadien-1-yl (cyclo-1,4-C6F7), pentafluoro-1,4-cyclohexadien-3-on-1-yl (cyclo-3-O-1,4-C6F5), CF2=C(CF3), (CF3)2CFC[triple bond]C, C4H9C[triple bond]C; Y = BF4, AsF6) in aHF showed, compared with XeF2-aHF, a quantitatively less distinct but qualitatively related dependence of delta(129Xe) vs temperature. The dependence of their delta(129Xe) values on concentration in aHF is negligible. An explanation for the different behavior of [RXe][Y] and XeF2 is offered.     

Ring contraction in the reaction of polyfluorinated tetralines with antimony pentafluoride. Formation of polyfluorinated indanes from tetralines

Heating of solutions of polyfluorinated tetralines containing chlorine or bromine atoms in the position 2 (2, 3) in SbF₅ at 200 - 240° leads to the contraction of the alicylic ring of tetraline to form polyfluorinated 1 - methylindanes. The six - membered alicyclic ring of perfluorotetraline and 1,1,4,4,- tetrachlorooctafluorotetraline doesn't undergo any changes under the same conditions. The probable route of this reaction is discussed.     

Reactions of pentafluorophenylxenon(II) hexafluoroarsenate [C6F5Ze] [AsF6] with halide anions in acetonitrile

Reactions of [C₆F₅Xe]⁺ [AsF₆]⁻ in acetonitrile with halide anions X⁻ show different results depending on X. If X = I, Br or Cl, then C₆F₅X is obtained. If X = F, then C₆F₅H and C₆F₅---C₆F₅ are produced, and if X = HF₂, then C₆F₆, C₆F₅H and C₆F₅---C₆F₅ are formed.     

Quantification of amorphous content in mixed systems: amorphous trehalose with lactose

There has been a lot of interest in quantification of the amorphous content of materials, especially when the amorphous content is a small percentage of the total mass. Whilst there has been success in studies on single materials, there has been little work showing how quantification of the amorphous content of one material can be undertaken in the presence of another. In this work isothermal microcalorimetry was used to measure the content of amorphous trehalose following mixing with crystalline lactose. Gravimetric water sorption studies revealed that trehalose did not form a complete dihydrate when exposed to 75% RH, presumably due to the rapid crystallisation of the outer regions of the particles. At 53% RH, the gravimetric studies showed dihydrate formation. The calorimetry data revealed that the crystallisation response was directly related to the mass of amorphous material in the mixture and was not affected by the mass of non-crystallising sample. It was shown that as long as there was a minimum mass of amorphous material (in this case 4 mg), it was possible to measure a crystallisation response with sufficient accuracy to allow quantification. Lower masses of amorphous content allowed detection, but less accurate quantification, as the response was superimposed on the initial calorimetric heat flow response. It was also found that the response at 53% RH in the TAM was less accurate due to the low peak height and long duration (compared to that seen at 75% RH). It can be concluded that the TAM method is well suited to both detection and quantification of amorphous content when there is one amorphous sample mixed with another (and thus presumably more than one) non-crystallising material.     

Diversity oriented synthesis of benzoxazoles and benzothiazoles

A combinatorial synthetic route yielding benzoxazoles and benzothiazoles is described. The use of o-halophenylisocyanides in the Ugi reaction (U-4CR) followed by a copper-catalyzed cyclization affords the benzoxazole as well as the benzothiazole moiety in good yield and high diversity.     

Trifluoropropynylxenon(II) tetrafluoroborate [CF3C[triple bond]CXe] [BF4]--isolation of an alkynylxenon(II) compound for the first time

The salt [CF3C[triple bond]CXe] [BF4] was prepared as neat compound by the reaction of the hitherto unknown alkynyldifluoroborane CF3C[triple bond]CBF2 with XeF2 in 1,1,1,3,3-pentafluoropropane (PFP) at -45 degrees C in 59% yield. [CF3C[triple bond]CXe] [BF4] was unambiguously characterised by multinuclear NMR spectroscopy in anhydrous HF (aHF) solution.     

The Reaction of 2‐X‐1, 2‐Difluoroalk‐1‐enyldifluoroboranes with Xenon Difluoride. A Methodical Approach to 1, 2‐Difluoroalk‐1‐enylxenon(II) Salts

2‐X‐1, 2‐Difluoroalk‐1‐enylxenon(II) salts were prepared by the reaction of XeF₂ with XCF=CFBF₂ (X = F, trans‐H, cis‐Cl, trans‐Cl, cis‐CF₃, cis‐C₂F₅) but no organoxenon(II) compounds were obtained when the trans‐isomers of boranes, trans‐XCF=CFBF₂ (X = CF₃, C₄F₉, C₄H₉, Et₃Si), were used under similar conditions.     

Liquid chromatographic-tandem mass spectrometric assay for the simultaneous quantification of Camptosar and its metabolite SN-38 in mouse plasma and tissues

A simple, rapid and sensitive LC-MS/MS bioanalytical method has been developed to simultaneously quantify Camptosar (CPT-11) and its active metabolite, SN-38, in mouse plasma and tissues. A single step protein precipitation with acetonitrile in 96-well plates was used for sample preparation. Camptothecin (CPT) was used as the internal standard. Fast separation of SN-38, CPT-11 and CPT was carried out isocratically on a C18, 2 mm x 50 mm, 5 microm HPLC column with a mobile phase containing acetonitrile and 20 mM ammonium acetate (pH 3.5) and a 2.5 min chromatographic run time. The API 4000 MS/MS system was operated in positive ionization multiple reaction monitoring mode, and the transitions for SN-38, CPT-11 and CPT were 393.4 --> 349.3, 587.6 --> 167.2 and 349.3 --> 305.3, respectively. The SN-38 and CPT-11 concentrations in samples were calculated from a standard curve of peak area ratios of the analyte to that of the internal standard using a 1/chi2 weighted linear regression. The quantitation limit of 0.5 ng/mL was achieved by using a low sample volume (100 microL) of plasma or tissue homogenates. The assay was linear over the concentration range of 0.5-500 ng/mL with acceptable precision and accuracy. The method was used for the quantification of CPT-11 and SN-38 in plasma and tissues to support a preclinical pharmacokinetics and tissue distribution study of CPT-11 in mice.