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Aging is characterized by inevitable organ function decline over time, with consequent body deterioration and increased susceptibility to death. Astragalus polysaccharide (APS) has been reported to have anti-oxidative, anti-apoptotic, and anti-inflammatory properties. We investigated the potential protective effects of APS on hydrogen peroxide (H

Highly enantioselective [3+3] and [3+4] annulations of isatin-derived enals with ethynylethylene carbonates and ethynyl benzoxazinanones are enabled by NHC/cooper cooperative catalysis, leading to a big library of spirooxindole derivatives in high structural diversity and enantioselectivity (up to 99 % ee). Both reactions represent a nicely synergistic integration of NHC and copper catalysis, in which both catalysts activate the substrates and the chiral NHC perfectly controls the stereochemistry.

An ionic association complex of methylene blue-tetraphenylborate ([MB]+·[B(C6H5)4]−) can emit a strong and stable fluorescence in KH2PO4-Na2HPO4 buffer solution. In the presence of bovine serum albumin (BSA), the fluorescence signal of [MB]+·[B(C6H5)4]− can be sharply quenched, which can be further quenched by using polyethylene glycol (PEG) as a sensitizer where the ΔF (ΔF=F0−F, F0 and F are the fluorescence intensities of the blank reagent and the test solution, respectively) of the system with PEG is 9.1 times higher than that without PEG, showing PEG has strong sensitizing effect on the quenching of a fluorescence signal. And there is a good linear correlation between ΔF and the content of BSA. Thus, a new fluorescence probe for the determination of trace protein has been established, with the linear range of 0.11–88.0 pg·L−1 and the detection limit of 22.0 ag·mL−1 BSA. This sensitive method has been applied to the determination of protein in human serum samples with satisfactory results. And the reaction mechanism was also discussed. Under the same condition, the new method can be used to determie not only BSA, human serum albumin (HAS), ovalbumin (OVA) and γ-globulin (γ-G), respectively, but also the total protein in serum, brain and spinal cord.

A Triton X-100-4.0G-D (4.0G-D refers to a 4.0-generation dendrimer) was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption (AA) reactions (direct method and sandwich method) were carried out between the labeling product of Triton X-100-4.0G-D-Wheat germ agglutinin (WGA) and alkaline phosphatase (ALP), the product of AA reaction preserved the good characteristics of room temperature phosphorescence (RTP) of 4.0G-D and ΔIP of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot−1 (corresponding concentration: 5.0×10−16 g·mL−1, namely 5.0×10−18 mol·L−1) for a direct method and 0.14 ag·spot−1 (corresponding concentration: 3.5×10−16 g·mL−1, namely 3.5×10−18 mol·L−1) for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully applied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed.

Among voltage-gated Ca2+ channels the non-dihydropyridine-sensitive alpha1E subunit is functionally less well characterized than the structurally related alpha1A (omega-agatoxin-IVA sensitive, P- /Q-type) and alpha1B (omega-conotoxin-GVIA sensitive, N-type) subunits. In the rat insulinoma cell line, INS-1, a tissue-specific splice variant of alpha1E (alpha1Ee) has been characterized at the mRNA and protein levels, suggesting that INS-1 cells are a suitable model for investigating the function of alpha1Ee. In alpha1E-transfected human embryonic kidney (HEK-293) cells the alpha1E-selective peptide antagonist SNX-482 (100 nM) reduces alpha1Ed- and alpha1Ee-induced Ba2+ inward currents in the absence and presence of the auxiliary subunits beta3 and alpha2delta-2 by more than 80%. The inhibition is fast and only partially reversible. No effect of SNX-482 was detected on the recombinant T-type Ca2+ channel subunits alpha1G, alpha1H, and alpha1I showing that the toxin from the venom of Hysterocrates gigas is useful as an alpha1E-selective antagonist. After blocking known components of Ca2+ channel inward current in INS-1 cells by 2 microM (+/-)-isradipine plus 0.5 microM omega-conotoxin-MVIIC, the remaining current is reduced by 100 nM SNX-482 from -12.4 +/- 1.2 pA/pF to -7.6 +/- 0.5 pA/pF (n = 9). Furthermore, in INS-1 cells, glucose- and KCl-induced insulin release are reduced by SNX-482 in a dose-dependent manner leading to the conclusion that alpha1E, in addition to L-type and non-L-type (alpha1A-mediated) Ca2+ currents, is involved in Ca2+ dependent insulin secretion of INS-1 cells.

The pksX polyketide synthase (PKS) genes were discovered in 1993 during genome sequencing of Bacillus subtilis 168. Although they represent one of the earliest examples of type I PKS gene clusters, their function has long remained enigmatic. Remarkably, immunogold labeling studies revealed that the PksX proteins assemble into a giant organelle-like structure with a diameter larger than 0.1 mm, which can be clearly observed by cryoelectron microscopy. A virtually identical gene cluster has recently been identified in the genome of Bacillus amyloliquefaciens FZB 42 and was assigned to the biosynthesis of bacillaene, a known antibiotic that had been largely uncharacterized because of its notorious instability. NMR studies of partially purified B. subtilis extracts ultimately revealed the structure of bacillaene to be the highly unsaturated enamine acid 1 (Scheme 1).

The power spectral density (PSD) analysis considering non-linearity is important in studying spectral efficiency of a digital modem for satellite systems. A general closed formula for numerical PSD calculation of quadrature overlapping modulations is derived in this paper. Four new quadrature overlapping modulation schemes are proposed because they have better spectral characteristics than those of conventional modulations, such as offset QPSK, MSK and staggered QORC, in both linear and nonlinear channels. The four new schemes are; overlapped minimum shift keying (OMSK), minimum shift keying triangular cosine (MSKTC), raised cosine triangular cosine (RCTC) and sinusoidal quadrature overlapped triangular cosine (SQOTC). The results show that for these new modulations, PSD side lobe regeneration caused by the channel non-linearity, is much less than that for the OQPSK, MSK and staggered QORC, a desirable feature enabling even tighter frequency band allocation in satellite communication systems. © 1997 John Wiley & Sons, Ltd.

Among several chiral bisphosphoric acids evaluated, oxygen-linked acid BNO provides the highest level of stereoselectivity.

The double hydrogen bonding activation of carbonyl functionality has been a general strategy for the design of amino amide organocatalysts for highly enantioselective direct aldol reactions of various ketones with aldehydes conducted in either organic solvents or aqueous media. Moreover, this concept may suggest an activation mode to create new catalysts for other related asymmetric transformations.

A chiral dinaphthyl-BINOL-derived phosphoric acid (NABIP) efficiently catalyzes the asymmetric intramolecular cycloaddition of formylphenoxybutenoates (I) and (IV) in the presence of α-amino-α-aryl esters (II).

Isoindoline derivatives with high enantiomeric purity (up to 98% ee) have been accessed by formal double arylation of azomethines.

A bisphosphoric acid-catalyzed 1,3-dipolar cycloaddition of buta-2,3-dienoates with azomethine ylides yields 3-methylenepyrrolidine derivatives with excellent enantioselectivity (up to 97% ee).

Organocatalytic enantioselective Biginelli and Biginelli-like reactions by chiral phosphoric acids derived from 3,3′-disubstituted binaphthols have been investigated. The size of 3,3′-substituents of the catalysts is able to control the stereochemistry of the Biginelli reaction. By tuning the 3,3′-disubstituents of the phosphoric acids, the stereochemistry of the Biginelli reaction can be reversed. This organocatalytic Biginelli reaction by Bronsted acids 12b and 13 is applicable to a wide range of aldehydes and various β-keto esters, providing a highly enantioselective method to access DHPMs. 3,3′-Di(triphenylsilyl) binaphthol-derived phosphoric acid afforded Biginelli-like reactions of a broad scope of aldehydes and enolizable ketones with benzylthiourea, giving structurally diverse dihydropyrimidinethiones with excellent optical purity. Theoretical calculations with the ONIOM method on the transition states of the stereogenic center forming step showed that the imine and enol were simultaneously activa...

The privileged spiro[pyrrolidin-3,3′-oxindole] derivatives exhibit important biological activities. An enantioselective organocatalytic approach to the rapid synthesis of spiro[pyrrolidin-3,3′-oxindole] derivatives with high enantiopurity and structural diversity is described. The asymmetric catalytic three-component 1,3-dipolar cycloaddition of a broad range of methyleneindolinones with aldehydes and amino esters in the presence of chiral phosphoric acid provides spirooxindole derivatives in high yield with unusual regiochemistry and excellent stereoselectivities (up to 98% ee) under mild conditions. The straightforward construction of spirooxindole skeletons with high stereo- and regioselectivity suggests a new avenue to medicinal chemistry and diversity-oriented synthesis. Theoretical calculations disclosed that both the azomethine ylide and the methyleneindolinone are hydrogen-bonded with the phosphoric acid, which accounted for the high enantio- and regioselectivity and indicated that the unusual reg...

On etudie le mouvement des parois de domaines ferroelectriques dans un cristal TGS dans lequel la transition de phase ordre-desordre ferroelectrique du second ordre prend place a la temperature de Curie