A new cyclisation involving cyclopropyl ketones. A short route to 1-aryltetralones.

Activated aryl aroylcyclopropanes cyclise with Lewis acids under mild conditions to 1-aryltetralones.     

The Domínguez–Lorenzo condition and multivalued nonexpansive mappings

Let E be a nonempty bounded closed convex separable subset of a reflexive Banach space X   which satisfies the Domínguez–Lorenzo condition, i.e., an inequality concerning the asymptotic radius of a sequence and the Chebyshev radius of its asymptotic center. We prove that a multivalued nonexpansive mapping T:E→2^X$T:E\to 2^X$ which is compact convex valued and such that T(E)$T(E)$ is bounded and satisfies an inwardness condition has a fixed point. As a consequence, we obtain a fixed-point theorem for multivalued nonexpansive mappings in uniformly nonsquare Banach spaces which satisfy the property WORTH, extending a known result for the case of nonexpansive single-valued mappings. We also prove a common fixed point theorem for two nonexpansive commuting mappings t:E→E$t:E\to E$ and T:E→KC(E)$T:E\to \mathit{KC}(E)$ (where KC(E)$\mathit{KC}(E)$ denotes the class of all compact convex subsets of E) when X is a uniformly convex Banach space.     

A measure of multivariate mutual complete dependence

The authors propose a multivariate version of Siburg and Stoimenov’s measure of mutual complete dependence. This multivariate version is, however, not the distance between a copula and the product copula $C_I$ under the modified Sobolev norm since the set of mutual complete dependence copulas does not lie on the sphere centered at $C_I$. To overcome this difficulty, the authors choose another center and define measures of complete dependence based on the modified Sobolev norm and this center. The measure of multivariate mutual complete dependence is then defined as the summation of the (normalized) measures of complete dependence.     

Evaluation of TILI-2 as an Anti-Tyrosinase,Anti-Oxidative Agent and Its Role in Preventing Melanogenesis Using a Proteomics Approach

There is a desire to develop new molecules that can combat hyperpigmentation. To this end, the N-terminal cysteine-containing heptapeptide TILI-2 has shown promising preliminary results. In this work, the mechanism by which it works was evaluated using a series of biochemical assays focusing on known biochemical pathways, followed by LC-MS/MS proteomics to discover pathways that have not been considered before. We demonstrate that TILI-2 is a competitive inhibitor of tyrosinase’s monophenolase activity and it could potentially scavenge ABTS and DPPH radicals. It has a very low cytotoxicity up to 1400 µM against human fibroblast NFDH cells and macrophage-like RAW 264.7 cells. Our proteomics study revealed that another putative mechanism by which TILI-2 may reduce melanin production involves the disruption of the TGF-β signaling pathway in mouse B16F1 cells. This result suggests that TILI-2 has potential scope to be used as a depigmenting agent.     

Continuous monitoring with microfabricated capillary electrophoresis chip devices

We report on the direct coupling of hydrodynamically flowing stream to a microchip capillary electrophoresis (CE) for continuous assays of liquid samples. The new interface relies on mounting the sample tubing onto a sharp inlet tip and allows rapid, convenient and reproducible electrokinetic loading from a continuously flowing stream directly into the narrow separation microchannel. The sharp inlet interface is characterized by its efficiency, stability and simplicity. The effect of the sample flow rate, applied voltages and other relevant variables, is described. It was found that the peak intensity is independent of the flow rate. The performance of the new interface is illustrated for on-line CE-electrochemical monitoring of phenolic and explosive compounds. Conditions simulating continuous long-term monitoring, led to a highly stable response for a 15 ppm 1,3,5-trinitrobenzene solution (RSD = 3.7%, n= 40). Such ability to continuously introduce flowing samples into micrometer channels makes 'lab-on-a-chip' devices highly compatible with real-life monitoring applications.     

Catalytic adsorptive stripping determination of trace chromium (VI) at the bismuth film electrode

A sensitive adsorptive stripping voltammetric protocol at a bismuth-coated glassy-carbon electrode for trace measurements of chromium (VI) in the presence of diethylenetriammine pentaacetic acid (DTPA) is described. The new protocol is based on accumulation of the Cr-DTPA complex at a preplated bismuth film electrode held at −0.80 V, followed by a negatively-going square-wave voltammetric waveform. Factors influencing the stripping performance including the film preparation, solution pH, DTPA and nitrate concentrations, deposition potential and deposition time, have been optimized. The resulting performance compares well with that observed for analogous measurements at mercury film electrodes. A preconcentration time of 7 min results in a detection limit of 0.3 nM Cr(VI) and after 2 min a relative standard deviation at 20 nM of 5.1% (n = 25). Applicability to river water samples is demonstrated. The attractive behavior of the new “mercury-free” chromium sensor holds great promise for on-site environmental and industrial monitoring of chromium (VI). Preliminary data in this direction using bismuth-coated screen-printed electrodes are encouraging.     

Reductive cleavage of cyclopropyl ketones

Aryl substituted cyclopropyl ketones are cleaved to acyclic ketones with zinc and zinc chloride or with zinc alone in refluxing alcohol.     

Novel Antimicrobial Peptides from a Cecropin-Like Region of Heteroscorpine-1 from Heterometrus laoticus Venom with Membrane Disruption Activity

The increasing antimicrobial-resistant prevalence has become a severe health problem. It has led to the invention of a new antimicrobial agent such as antimicrobial peptides. Heteroscorpine-1 is an antimicrobial peptide that has the ability to kill many bacterial strains. It consists of 76 amino acid residues with a cecropin-like region in N-terminal and a defensin-like region in the C-terminal. The cecropin-like region from heteroscorpine-1 (CeHS-1) is similar to cecropin B, but it lost its glycine-proline hinge region. The bioinformatics prediction was used to help the designing of mutant peptides. The addition of glycine-proline hinge and positively charged amino acids, the deletion of negatively charged amino acids, and the optimization of the hydrophobicity of the peptide resulted in two mutant peptides, namely, CeHS-1 GP and CeHS-1 GPK. The new mutant peptide showed higher antimicrobial activity than the native peptide without increasing toxicity. The interaction of the peptides with the membrane showed that the peptides were capable of disrupting both the inner and outer bacterial cell membrane. Furthermore, the SEM analysis showed that the peptides created the pore in the bacterial cell membrane resulted in cell membrane disruption. In conclusion, the mutants of CeHS-1 had the potential to develop as novel antimicrobial peptides.     

Electron impact studies. CI—negative ion mass spectra of the carbonyl group. The Aryl?CH2?CO- and Aryl?(CH2)2?CO- systems

Fragmentations of the molecular anions of m- and p-nitrophenyl-CH₂? CO? R yield nitrobenzyl anions in the ion source when R = Ph, but the corresponding ion from the system where R = Me is only formed after collision activation. o- and p-Nitrophenyl parent anions undergo β-cleavage to the carbonyl centre to produce nitrobenzyl anions. Pronounced rearrangement peaks are noted in the spectra of o-nitrophenyl- compounds. Labelling studies indicate the identity of the eliminated species, but the mechanisms of the rearrangements are complex.     

A Protein from Aloe vera that Inhibits the Cleavage of Human Fibrin(ogen) by Plasmin

A protease inhibitor protein with the molecular mass of 11,804.931 Da (analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) was isolated from Aloe vera leaf gel and designated as AVPI-12. The isoelectric point of the protein is about 7.43. The first ten amino acid sequence from the N-terminal was found to be R–D–W–A–E–P–N–D–G–Y, which did not match other protease inhibitors in database searches and other publications, indicating AVPI-12 is a novel protease inhibitor. The band protein of AVPI-12 migrated further on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) than reducing SDS-PAGE. This result indicated that the molecule of AVPI-12 did not contain interchain disulfide bonds, but appeared to have intrachain disulfide bonds instead. AVPI-12 strongly resisted digestion by the serine proteases human plasmin and bovine trypsin. The protein could protect the γ-subunit of human fibrinogen from plasmin and trypsin digestion, similar to the natural plasma serine protease inhibitor α₂-macroglobulin. The protein also could protect the γ-subunit of fibrinogen from the cysteine protease papain. AVPI-12 also exhibited dose-dependent inhibition of the fibrinogenolytic activity of plasmin, similar to α₂-macroglobulin. The fibrinolytic inhibitory activity of AVPI-12 and the small-angle X-ray scattering showed that the protein could protect human fibrin clot from complete degradation by plasmin. The inhibition of the fibrinogenolytic and fibrinolytic activities of plasmin by AVPI-12 suggests that the inhibitor has potential for use in antifibrinolytic treatment.