Reduction par les sels chromeux de bromures benzyliques ortho-o-acyles avec transposition du groupement acyle : De l'' ester : acces aux ortho-hydroxybenzyl cetones non masquees et une nouvelle preparation de benzo¦b¦furannes substitues en position-2

The σ-bonded organochromium (III) complexes resulting from the reduction of -O-acyl benzylic bromides with CrCl₂., undergo an 1,5-transposition of the ester acyl functional group which allows, through selected experimental conditions either a selective access to the unmasked -hydroxybenl ketones or a new preparation of the 2-substituted benzo¦b¦furans . The scope and limitations of the method are presented.     

Evaluation of a high-performance thin-layer chromatographic technique for the determination of salbutamol serum levels in clinical trials.

Salbutamol concentrations were determined by high-performance thin-layer chromatography in the sera of two sets of ten volunteers at hourly intervals for 6 h after taking one 8-mg slow-release tablet. The influence of time lapse in processing of serum samples, i.e. centrifugation, extraction and chromatography, was studied. A statistical significant instability of salbutamol in the sera of patients was found which was not present in standard drug-free serum samples spiked with salbutamol and used for construction of standard curves.     

Screening an In-House Isoquinoline Alkaloids Library for New Blockers of Voltage-Gated Na+ Channels Using Voltage Sensor Fluorescent Probes: Hits and Biases

Voltage-gated Na⁺ (Na_V) channels are significant therapeutic targets for the treatment of cardiac and neurological disorders, thus promoting the search for novel Na_V channel ligands. With the objective of discovering new blockers of Na_V channel ligands, we screened an In-House vegetal alkaloid library using fluorescence cell-based assays. We screened 62 isoquinoline alkaloids (IA) for their ability to decrease the FRET signal of voltage sensor probes (VSP), which were induced by the activation of Na_V channels with batrachotoxin (BTX) in GH3b6 cells. This led to the selection of five IA: liriodenine, oxostephanine, thalmiculine, protopine, and bebeerine, inhibiting the BTX-induced VSP signal with micromolar IC₅₀. These five alkaloids were then assayed using the Na⁺ fluorescent probe ANG-2 and the patch-clamp technique. Only oxostephanine and liriodenine were able to inhibit the BTX-induced ANG-2 signal in HEK293-hNa_V1.3 cells. Indeed, liriodenine and oxostephanine decreased the effects of BTX on Na⁺ currents elicited by the hNa_V1.3 channel, suggesting that conformation change induced by BTX binding could induce a bias in fluorescent assays. However, among the five IA selected in the VSP assay, only bebeerine exhibited strong inhibitory effects against Na⁺ currents elicited by the hNav1.2 and hNav1.6 channels, with IC₅₀ values below 10 µM. So far, bebeerine is the first BBIQ to have been reported to block Na_V channels, with promising therapeutical applications.     

The Antioxidant and Hypolipidemic Effects of Mesona Chinensis Benth Extracts

In this study, the antioxidant and hypolipidemic effects of Mesona Chinensis Benth (MCB) extracts were evaluated. Seven fractions (F0, F10, F20, F30, F40, F50 and MTF) were obtained from the MCB ethanol extracts. Compared to the commercial antioxidants (vitamin C), MTF and F30 exhibited higher antioxidant activities in the antiradical activity test and the FRAP assay. The half-inhibition concentration (IC50) for MTF and F30 were 5.323 µg/mL and 5.278 µg/mL, respectively. MTF at 200 µg/mL significantly decreased the accumulation of TG in oleic acid (OA)-induced HepG2 cells and reversed the inhibitory effect of Compound C on AMPK (MTF and F30 significantly increased the glucose utilization of insulin-induced HepG2 cells). In addition, the components of MTF were identified by HPLC-MS, which were caffeic acid, quercetin 3-O-galactoside, isoquercetin, astragalin, rosmarinic acid, aromadendrin-3-O-rutinoside, rosmarinic acid-3-O-glucoside and kaempferol-7-O-glucoside. Through statistical correlations by Simca P software, it was found that the main antioxidant and hypolipidemic components of MCB might be caffeic acid, kaempferol-7-O-glucoside, rosmarinic acid-3-O-glucoside and aromadendrin-3-O-rutinoside, which may play important roles in the AMPK pathway. MTF and F30 in MCB could be potential health products for the treatment of hyperlipidemia.     

硅烷化磁铁粉固定胰蛋白酶的研究

分别以硅烷化磁铁粉、硅烷磁化脱乙酰几丁质及脱乙酰几丁质作载体,甲醛或戊二醛为交联剂,对胰蛋白酶的固定化条件及所制备的固定化酶的性质进行了研究．研究了载体种类、交联剂和ｐＨ值以及载体与酶比例等因素对胰蛋白酶固定化的影响．研究了不同载体固定胰蛋白酶的特点,证明以硅烷化试剂和甲醛作交联剂的硅烷化磁铁粉作胰蛋白酶固定化的载体具有明显优点,所制备的硅烷化磁铁粉固定化胰蛋白酶酶学性质明显优于可溶性胰蛋白酶     

Acetylenic and diacetylenic liquid-crystalline monomers: towards ordered conjugated polymers

Abstract

Acetylenic and diacetylenic mesomorphic monomers have been prepared in order to obtain long conjugated polymers able to give high non-linear optical hyperpolarizabilities. Here we report the synthesis of such monomers incorporating cholesteryl and methoxybiphenyl groups; their structural and thermal behaviour are described. The occurrence of mesophases in the acetylenic and diacetylenic derivatives is discussed as a function of the spacer length and of the size of the mesogen moiety. The diacetylenic derivatives containing the methoxybiphenyl groups do not exhibit any liquid-crystalline behaviour but are able to polymerize under U.V. radiation.     

On one possibility of determining the atom position in the crystal unit cell

The possibility of the determination of the position of an atom incorporated in the crystal unit cell by measuring the yield of characteristic radiation of this atom, excited by an X-ray wave nonuniform over the cell cross section, is shown. Such a wave can appear, in particular, in the mode of dynamical diffraction of an ordinary plane wave.     

Indentation-induced deformations of GaAs(011) at a high temperature

Indentation tests were performed at a high temperature on GaAs(011). This orientation allowed the activation of normal and inclined slip systems. Samples with two different thicknesses were prepared and a large range of loads was used. Observations on decreasing scales were carried out using different microscopies and more particularly transmission electron microscopy on thin foils prepared by the focused-ion-beam technique. The back side of the thinnest samples could be deformed using the highest loads. The deformation was observed to be anisotropic on the back side as well as at the indented surface. On one side of the indentation, an anisotropic climb of matter was revealed and associated with microtwinning development. Convergent-beam electron diffraction as well as chemical etching allowed us to determine rigorously the polarity of the samples and the character of dislocations ( for g) generated by the indenter. The dislocations extending deeper into the samples were determined to be fdislocations. This result was discussed in view of the difference between the core reconstructions and mobilities of fand gdislocations.