Synthesis and structure elucidation of some new azo dye from hydroxyquinolin-2(<Emphasis Type="Italic">1H</Emphasis>)-one derivatives and their antimicrobial evaluation

The aim of the work is synthesis of some novel azo dye from 1,2-dihydro-4-hydroxy-2-oxoquinoline-6-sulfonic acid (3), 4-hydroxy-6-methoxyquinolin-2(1H)-one (4), and 4-hydroxy-6-nitroquinolin-2(1H)-one (5). The prepared compounds were screened for antibacterial against Staphylococcus aureus, Escherichia coli, and antifungal activity against Candida sp., Aspergillus multi and Aspergillus niger. The structure of newly compounds was characterized by ¹H-NMR, IR and elemental analysis.     

IR-MALDI ion mobility spectrometry: physical source characterization and application as HPLC detector

Infrared matrix-assisted laser dispersion and ionization (IR-MALDI) in combination with ion mobility (IM) spectrometry enables the direct analysis of biomolecules in aqueous solution. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse, which disperses the liquid as vapor, nano- and micro-droplets. The ionization process is characterized initially by a broad spatial distribution of the ions, which is a result of complex fluid dynamics and desolvation kinetics. These processes have a profound effect on the shape and width of the peaks in the IM spectra. In this work, the transport of ions by the phase explosion-induced shockwave could be studied independently from the transport by the electric field. The shockwave-induced mean velocities of the ions at different time scales were determined through IM spectrometry and shadowgraphy. The results show a deceleration of the ions from 118 m?s^?1 at a distance of 400 μm from the liquid surface to 7.1 m?s^?1 at a distance of 10 mm, which is caused by a pile-up effect. Furthermore, the desolvation kinetics were investigated and a first-order desolvation constant of 325?±?50 s^?1 was obtained. In the second part, the IR-MALDI-IM spectrometer is used as an HPLC detector for the two-dimensional separation of a pesticide mixture.     

New cytotoxic constituents from the Red Sea soft coral Nephthea sp.

Nephthea are soft coral species rich in sesquiterpenoids and steroids. An organic extract of Nephthea sp. resulted in the isolation of a new steroid (1), as well as several previously reported metabolites (2–9). Structures were elucidated by employing NMR and HR-EI-MS analyses. The total extract, fractions and purified compounds exhibited differential cytotoxicity against the breast cancer MCF-7 cell line.     

Equifocality of a singular Riemannian foliation

A singular foliation on a complete Riemannian manifold is said to be Riemannian if each geodesic that is perpendicular to a leaf at one point remains perpendicular to every leaf it meets. We prove that the regular leaves are equifocal, i.e., the end point map of a normal foliated vector field has constant rank. This implies that we can reconstruct the singular foliation by taking all parallel submanifolds of a regular leaf with trivial holonomy. In addition, the end point map of a normal foliated vector field on a leaf with trivial holonomy is a covering map. These results generalize previous results of the authors on singular Riemannian foliations with sections.

     

Time-domain fluorescence lifetime imaging for intracellular pH sensing in living tissues

pH sensing in living cells represents one of the most prominent topics in biochemistry and physiology. In this study we performed one-photon and two-photon time-domain fluorescence lifetime imaging with a laser-scanning microscope using the time-correlated single-photon counting technique for imaging intracellular pH levels. The suitability of different commercial fluorescence dyes for lifetime-based pH sensing is discussed on the basis of in vitro as well of in situ measurements. Although the tested dyes are suitable for intensity-based ratiometric measurements, for lifetime-based techniques in the time-domain so far only BCECF seems to meet the requirements of reliable intracellular pH recordings in living cells.     

Ethanol oxidation at metal–zeolite-modified electrodes in alkaline medium. Part-1: gold–zeolite-modified graphite electrode

Gold–zeolite-modified graphite (AuZG) electrode shows higher catalytic activity for ethanol oxidation in alkaline medium compared with massive gold or gold-modified graphite (Au/G) electrodes. The activity of this electrode depends on the amount of zeolite loaded on the graphite surface and on the soaking time in Au³⁺ solution. The effects of both scan rate and ethanol concentration on the anodic peak height are indicatives of a diffusion-controlled process. Current decay measurements indicate that the activity of studied electrodes towards poisoning tolerance decreases in the following order: AuZG > Au/G > Au. This paper is dedicated to Prof. Dr. T. Iwasita for her 65th birthday.     

Negombins A-I, new chlorinated polyfunctional diterpenoids from the marine sponge Negombata species

Nine novel compounds designated negombins A-I (1-9) were isolated, together with latrunculin, from the Tanzanian sponge Negombata sp. The nine are sacculatane type diterpenes, previously only known from liverworts. The structures of the compounds were elucidated by interpretation of MS and 1D and 2D NMR spectra. A possible biogenesis initiated by the naturally rare chloronium ion is suggested, possibly hinting to a guest microorganism as the source of the compounds. Compound 4 is toxic to brine shrimp larvae.     

Electrical probing of endothelial cell behaviour on a fibronectin/polystyrene/thiol/gold electrode by Faradaic electrochemical impedance spectroscopy (EIS)

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kOmega cm(2) with no large defects in the cell layer, and a specific capacitance equal to few microF cm(-2) explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.     

Synthesis and in vitro evaluation of new benzothiazole derivatives as schistosomicidal agents

A series of benzothiazol-2-yl-dithiocarbamates 3a-d along with their copper complexes 4a-c were synthesized via the reaction of suitable alkyl, aralkyl or heteroaryl halides with the sodium salt of benzothiazol-2-yl-dithiocarbamic acid, followed by complexation with copper sulphate. N-(4-Acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl)-N-benzothiazol-2-yl-acetamides 7a-c were synthesized by cyclization of the appropriate thiosemicarbazones 6a-c in acetic anhydride. Selected compounds were screened for in vitro schistosomicidal activity against Schistosoma mansoni at three different dosage levels (10, 50 and 100 microg/mL). Three of these products, 4a-c, showed schistosomicidal activity similar to praziquantel, with 100% worm mortality at 10 microg/mL. These compounds would constitute a new class of potent schistosomicidal agents.