Enhanced mass detection of oligonucleotides using reverse-phase high-performance liquid chromatography/electrospray ionization ion-trap mass spectrometry

A new method providing enhanced sensitivity for the analysis of oligonucleotides using an on-line coupled system of reversed-phase high-performance liquid chromatography (RP-HPLC) and electrospray ionization ion-trap mass spectrometry (ESI-MS) has been developed. The presented method allows the use of the standard gradient elution of 0.1 M triethylammonium acetate (TEAA) buffer (adjusted to pH 7.0 with acetic acid) and acetonitrile that is typically used for the separation of oligonucleotides in RP-HPLC. An added feature of this method is the ability to combine and mix additional 0.1 M imidazole in acetonitrile after the separation column for improved ESI-MS performance. This is similar to the post-column reaction method in liquid chromatography (LC) and the liquid sheath flow method in LC/ESI-MS, both of which offer the advantage of not compromising the chromatographic separation conditions. The application of this new method is demonstrated to afford improved sensitivity for the analysis of oligonucleotides (20-50 mer) via on-line coupled HPLC/ESI-MS analysis and purification systems.     

Dichloro­(4,4′‐dialkyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), where alkyl is pentyl and heptyl

Dichloro­(4,4′‐dipentyl‐2,2′‐bipyridine‐κ²N,N′)platinum(II), [PtCl₂(C₂₀H₂₈N₂)], adopts a discrete π–π stacking structure, where the alkyl chains are located in a random manner. In contrast, dichloro­(4,4′‐diheptyl‐2,2′‐bipyridine‐κ²N,N′)platinum(II), [PtCl₂(C₂₄H₃₆N₂)], forms a layer structure comprised of alkyl chain layers and paired coordination sites, as observed for analogous complexes with longer alkyl chains.     

Anti-Phototoxicity Effect of Phenolic Compounds from Acetone Extract of Entada phaseoloides Leaves via Activation of COX-2 and iNOS in Human Epidermal Keratinocytes

The extract from Entada phaseoloides was employed as active ingredients of natural origin into cosmetic products, while the components analysis was barely reported. Using LC-DAD-MS/qTOF analysis, eleven compounds (1–11) were proposed or identified from acetone extract of E. phaseoloides leaves (AE). Among them, six phenolic compounds, protocatechuic acid (2), 4-hydroxybenzoic acid (3), luteolin-7-O-β-d-glucoside (5), cirsimaritin (6), dihydrokaempferol (9), and apigenin (10), were isolated by various chromatographic techniques. Protocatechuic acid (2), epicatechin (4), and kaempferol (11) at a concentration 100 μM increased the HaCaT cells viability of the UVB-irradiated cell without any cytotoxicity effect and reduced the expression of COX-2 and iNOS inflammation gene. Moreover, compounds 2 and 4 could have potent effects on cell migration during wound closure. These results suggest that compounds 2, 4, and 11 from AE have anti-photoaging properties and could be employed in pharmaceutical and cosmeceutical products.     

Facile and stereoselective access to nonracemic tricyclic cyclobutanes by asymmetric intramolecular Michael-aldol reaction: thermodynamic equilibrium and activation by iodonium ion.

Intramolecular Michael-aldol reactions of (-)-phenylmenthyl enoates tethered to cycloalkanone affords tricyclic cyclobutanes with high degrees of diastereochemical control. Kinetic and thermodynamic studies revealed that the Michael-aldol reaction is reversible under conditions in which trimethylsilyl iodide is used in the presence of hexamethyldisilazane at ambient temperature. Different levels of diastereoselectivity are observed when this cyclization process is carried out under kinetic vs thermodynamic conditions. Finally, an influence of added iodonium donors on the reaction rate has been noted.     

The synthesis of benzofuroquinolines. I. Some benzofuro[2,3-b]quinoline and benzofuro[3,2-c]quinoline derivatives

Benzofuro[2,3-b]quinoline ( Ia ) and its 11-methyl derivative ( Ib ) were synthesized by demethylcyclization of 3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-ones (VIa,b). Benzofuro[2,3-b]quinoline-11-carboxylic acid (Id) was synthesized by chlorination followed by the action of potassium hydroxide of a lactone (IX) prepared by demethyl-cyclization of 3-(o-methoxyphenyl)-2-oxo-1,2-dihydroquinoline-4-carboxylic acid (VIII). Isomeric benzofuro[3,2-c]quinoline (Ha) and its 6-methyl derivative (IIb) were synthesized by demethyl-cyclization of 3-(o-methoxyphenyl)-1,4-dihydroquinolin-4-ones (XIa,b). Both the methyl derivatives (Ib and IIb) were converted to the carboxylic acids (Id and IId) through condensation with benzaldehyde followed by oxidation. The benzofuroquinolines (Ia,b,d and IIa,b) thus obtained were oxidized to the corresponding N-oxides (IIIa,b,d and IVa,b).     

Polypeptide-synthetic polymer hybrids, 1. Miscibility of poly(vinyl alcohol) with poly(sodium α,β-D,L-aspartate)

The present paper describes materials of polypeptide-commodity polymer hybrids from poly(vinyl alcohol) (PVA) and poly(sodium α,β-D ,L -aspartate) ( 1 ). Miscible blend films of polypeptide 1 and PVA were prepared by the solvent-cast method from a homogeneous aqueous solution. Differential scanning calorimetry. Fourier transform infrared, and scanning electron microscopy combined with energy dispersive X-ray spectroscopy (EDX) were used to investigate the blends. It was revealed that 1 and PVA are miscible in a wide range of compositions.     

Paramagnetic Faraday rotation with spin-polarized ytterbium atoms

We report the observation of paramagnetic Faraday rotation of spin-polarized ytterbium (Yb) atoms. As the atomic samples, we used an atomic beam, released atoms from a magneto-optical trap (MOT), and trapped atoms in a far-off-resonant trap (FORT). Since Yb is diamagnetic and includes a spin-1/2 isotope, it is an ideal sample for spin physics, such as quantum non-demolition measurement of spin (spin QND), for example. From the results of the rotation angle, we confirmed that the atoms were almost perfectly polarized. PACS 32.80.Bx; 32.80.Pj; 42.25.Lc     

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)₃] successfully yielded linear polyesters having hydroxyl functionality (M_n = ca. 1.0 × 10⁴). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009     

Initial relaxation times in dynamic light scattering from once-broken rod molecules in solution

Initial relaxation times determined by the initial decay rate of the time correlation function of scattered light are calculated for the once-broken rod model (two rigid rods of equal length connected by a universal joint) following the Fujiwara–Saito theory. The coefficient C describing the initial angular dependence of the first cumulant of the correlation function is also calculated. The results are compared with Pecora's results based on the Yu–Stockmayer theory for this model; and it is shown that the Fujiwara–Saito theory gives reasonable results.