Separation of O- and C-allyl glycoside anomeric mixtures by capillary electrophoresis and high-performance liquid chromatography

Rapid and reliable methods for the analysis of O- and C-allyl galactopyranosides and glucopyranosides are presented, based on capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC). In MEKC, the formation of chromophoric and charged complexes between the saccharides and borate as well as the hydrophobic interactions with micelles jointly contributed to the selective separation and sensitive detection of all the investigated anomeric couples. Some non-purified synthesis mixtures of C-allyl glycosides were successfully characterised without pre-treatment. MEKC buffer conditions for which glycosides separation was successfully achieved were then exported and applied to reverse-phase liquid chromatography (RP-HPLC), for the quantitative isolation of each allyl glycoside anomer. Identification of the obtained anomeric products was performed by electrospray mass spectrometry and (13)C NMR spectroscopy. Glycoside-solvent interactions driving the selective anomeric separation were shortly addressed and discussed on the basis of sugar derivatives structural differences.     

Unsupervised classification of children’s bodies using currents

Object classification according to their shape and size is of key importance in many scientific fields. This work focuses on the case where the size and shape of an object is characterized by a current. A current is a mathematical object which has been proved relevant to the modeling of geometrical data, like submanifolds, through integration of vector fields along them. As a consequence of the choice of a vector-valued reproducing kernel Hilbert space (RKHS) as a test space for integrating manifolds, it is possible to consider that shapes are embedded in this Hilbert Space. A vector-valued RKHS is a Hilbert space of vector fields; therefore, it is possible to compute a mean of shapes, or to calculate a distance between two manifolds. This embedding enables us to consider size-and-shape clustering algorithms. These algorithms are applied to a 3D database obtained from an anthropometric survey of the Spanish child population with a potential application to online sales of children’s wear.     

A novel enantiospecific route to 10-hydroxyfenchone: a convenient intermediate for C(10)-O-substituted fenchones

A novel, highly efficient enantiospecific preparation of 10-hydroxyfenchone from commercially available fenchone is described. The three-step synthetic route is based on two consecutive Wagner–Meerwein rearrangements of the fenchone skeleton, taking place with a high overall yield. This straightforward access to optically active 10-hydroxyfenchone, together with the scope for further functionalisation of the hydroxyl group, makes 10-hydroxyfenchone a convenient key intermediate to other optically active C(10)-O-substituted fenchones, which are analogues of well-known C(10)-O-substituted camphor-derived chiral sources.     

1,3-dipolar cycloadditions of diazoalkanes to activated sulfoxides: influence of Lewis acids

[reaction: see text] The reactions of diazomethane and diazoethane with (S)-3-p-tolylsulfinylfuran-2(5H)-one (3) and its 4-methyl derivative (4) have been studied. The sulfinyl group was able to completely control the pi-facial selectivity of all these reactions, which decreased when the polarity of the solvent increased and could be inverted in the presence of Lewis acids, Yb(OTf)(3) being the most efficient catalyst. This behavior made possible the stereodivergent synthesis of diastereoisomeric pyrazolines in almost quantitative yields and de's higher than 98%. The endo/exo selectivity was also complete in reactions of 3 with diazoethane, whereas 4 afforded an easily separable 1:1 mixture of diastereoisomers. Steric factors accounts for the endo/exo selectivity, whereas electrostatic interactions must also be considered to explain the facial selectivity.     

Molecular mechanics studies of the conformations of metal complexes of 1,4,7,10,13,16-hexaazacyclooctadecane: Calculations of macrocyclic cavity size

Molecular mechanics calculations are reported on metal complexes of 18-azacrown-6. Four possible conformations are considered which encapsulate the metal in different geometric environments, namely, chiral octahedral, meso octahedral, trigonal prismatic, and hexagonal bipyramidal. Crystal structures are available for all but the last geometry, and molecular mechanics calculations show an excellent fit to the experimental data. The strain energy of the macrocycle has been calculated for a range of M-N distances, and thus the hole size of the macrocycle has been obtained for various conformations. Two different methods were used to calculate the strain energy of the metal environment. We either used the conventional molecular mechanics term for angle bending,k _b — ₀)², and chose the ideal angles to fit the particular metal geometry, or we set the angle force constants to zero and introduced 1,3 van der Waals interactions between the ligand donor nitrogen atoms. Results from the two methods are compared.     

Derivatives of benzo[4,5]cyclohepta[1,2-b]thiophene. 4. Synthesis of 1-(9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-4-yl)-3-alkylaminoazetidines

Thirteen 1-(9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-4-yl)-3-alkylaminoazetidines 11 have been synthesized in three steps from 4-amino-9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophene ( 6 ), which was obtained from the reduction of either 4-azido 4 or 4-hydroxyimino 5 derivatives. All the compounds have been evaluated as potential antidepressive agents.     

2,5,-Dimethoxy- and 2,5-di-n-butoxy-1,4-benzoquinone reactions and polymerization with 1,6-hexanediamine

The serendipitous formation of 2,5-dimethoxy- 1,4-benzoquinone is reported from the reaction of 1,4-benzoquinone with methanol, DABCO, and paraformaldehyde. This monomer, and its di-n-butoxy analog, are also available from 2,5-dihydroxy-1,4-benzoquinone. These materials are capable of novel polycondensation reactions with diamines such as 1,6-hex-anediamine. Use of m-crexsol as polymerization solvent gave a dark, insoluble product while various amide solvents lead to orange or pink polymers that had average degrees of polymerization from 5 up to >30. These polymers, Plus model compounds obtained from 1-aminopropane and N,N'- dimethyl-1,6-hexanediamine, were characterized by FTIR, solution, and solid-state NMR.     

Site-Directed Mutagenesis of Cytochrome P450 2D6 and 2C19 Enzymes: Expression and Spectral Characterization of Naturally Occurring Allelic Variants

Genetic polymorphism of the cytochrome P450 (CYP) genes particularly affects CYP2D6 and CYP2C19 to a functionally relevant extent, and it is therefore crucial to elucidate the enzyme kinetic and molecular basis for altered catalytic activity of these allelic variants. This study explored the expression and function of the reported alleles CYP2D6*2, CYP2D6*10, CYP2D6*17, CYP2C19*23, CYP2C19*24, and CYP2C19*25 with respect to gene polymorphisms. Site-directed mutagenesis (SDM) was carried out to generate these six alleles. After DNA sequencing, the CYP2D6 and CYP2C19 wild types alongside with their alleles were each independently co-expressed with NADPH-CYP oxidoreductase (OxR) in Escherichia coli. The expressed proteins were analyzed using Western blotting, reduced carbon monoxide (CO) difference spectral scanning, and cytochrome c reductase assay. Results from Western blot revealed the presence of all CYP wild-type and allelic proteins in E. coli membrane fractions. The reduced CO difference spectra scanning presented the distinct peak of absorbance at 450 nm, and the cytochrome c reductase assay has confirmed that spectrally active OxR was expressed in each protein preparation. As a conclusion, the results obtained from this study have proven the CYP variants to be immunoreactive and spectrally active and are suitable for use to examine biotransformation and interaction mechanism of the enzymes.     

Automated phase retrieval of a single-material object using a single out-of-focus image

Phase retrieval is widely used in phase contrast microscopy. Here we present an autofocus algorithm that allows the phase of the exit wave function, from a single-material object, to be reconstructed at medium resolution from a single phase contrast image without any a priori knowledge of the imaging system or object. The algorithm is demonstrated on coherent out-of-focus electron micrographs of 30 nm latex sphere calibration standards, giving <10% RMS error over a large defocus range.