Synthesis and evaluation of antitrypanosomal activity of some thiosemicarbazide derivatives of 1-butyl-6-fluoro-7-morpholino-4-oxo-1,4-dihydroquinoline-3-carboxylic acid

The synthesis of thiosemicarbazide of 1-butyl-6-fluoro-7-morpholino-4-oxo-1,4-dihydroquinoline-3-carboxylic acid as well as its heterocyclic derivatives – 1,3,4-thiadiazole and 1,2,4-triazole are described; the modification of proper 1,2,4-triazole derivative by maleimides is also presented. Spectral properties of the prepared compounds and X-ray analysis for the selected compounds were studied. For the compounds antitrypanosomal potential and the toxicity were determined.     

Isomorphisms of Some Complex Poisson Brackets

Given a complex manifold M_i, structures of Poisson algebras on (M_i)=C(M_i,C) which are associated with a nondegenerate -closed (2,0)-form _i on M_i are considered. It is shown that every isomorphism of Poisson structures (M₁) (M₂) is generated by a biholomorphic map :M₂ M₁ such that ₂ = *₁     

Helical rosette nanotubes with tunable stability and hierarchy

The design of nanostructured materials with tunable dimensions and properties that maintain their structural integrity under physiological conditions is a major challenge in biomedical engineering and nanomedicine. Helical rosette nanotubes (HRN) are a new class of materials produced through a hierarchical self-assembly process of low molecular weight synthetic organic modules in water. Here, we describe a synthetic strategy to tune their stability and hierarchy by preorganization of the self-assembling units, control of net charge per unit of nanotube surface area, amphiphilicity, and number of H-bonds per self-assembling module, and through peripheral steric (de)compression. Using these criteria, HRNs with tunable stability and hierarchical architecture were produced from self-assembling modules that (a) persist as individual molecules in solution, (b) self-assemble into HRN but denature at high temperature (<85 degrees C), (c) self-assemble into HRN whose structural integrity persists even in boiling water (>95 degrees C), and (d) self-assemble into well-dispersed short nanotubes, long nanotubes, ribbons, or superhelices. Given the biocompatibility, synthetic accessibility, and chemical and physical tunability of these materials, numerous applications in biomedical engineering, materials science, and nanoscience and technology are envisioned.     

Synthesis, Structure and Selective Upper Rim Functionalization of Long Chained Alkoxythiacalix[4]arenes

The synthesis and X-ray structure investigation of the cone shaped monodecyloxythiacalix[4]arene, as well as the introduction of the reactive bromide or chloromethyl groups on it’s upper rim are described. Preparation of the amphiphilic derivative of thiacalixarene bearing three hydrophilic diethoxyphosphoryl groups at the upper rim and lipophilic decyloxy group at the lower rim is presented.     

RNA Interference Controlled by Light of Variable Wavelength

Known molecular, “caged” siRNAs are activated by UV light. Since the light of this type is toxic to cells, the uncaging can cause undesired side effects. A modular, molecular system for designing siRNAs is reported, which can be activated by non‐toxic light in live cells. For example, siRNAs responsive to green and red light are described. The uncaging is mediated by ¹O₂ photogenerated on a photosensitizer, which is attached to the 3′‐terminus of the lagging strand. The 5′‐terminus of the guide strand is alkylated (“caged”) with a 9‐anthracenyl residue. The latter fragment reacts with the ¹O₂ with formation of the free (uncaged) 5′‐OH terminus. Simultaneously with the uncaging the photosensitizer is bleached and no more ¹O₂ is generated after this process is completed. The photoactivation of the siRNAs described here is not toxic to cells.     

Kinetics of ethanol decay in mouth‐ and nose‐exhaled breath measured on‐line by selected ion flow tube mass spectrometry following varying doses of alcohol

A study has been carried out of the decay of ethanol in mouth‐exhaled and nose‐exhaled breath of two healthy volunteers following the ingestion of various doses of alcohol at different dilutions in water. Concurrent analyses of sequential single breath exhalations from the two volunteers were carried out using selected ion flow tube mass spectrometry, SIFT‐MS, on‐line and in real time continuously over some 200 min following each alcohol dose by simply switching sampling between the two volunteers. Thus, the time interval between breath exhalations was only a few minutes, and this results in well‐defined decay curves. Inspection of the mouth‐exhaled and nose‐exhaled breath data shows that mouth contamination of ethanol diminished to insignificant levels after a few minutes. The detailed results of the analyses of nose‐exhaled breath show that the peak levels and the decay rates of breath ethanol are dependent on the ethanol dose and the volume of ethanol/water mixture ingested. From these data, both the efficiency of the first‐pass metabolism of ethanol and the indications of gastric emptying rates at the various doses and ingested volumes have been obtained for the two volunteers. Additionally and simultaneously, acetaldehyde, acetic acid and acetone were measured in each single breath exhalation. Acetaldehyde, the primary product of ethanol metabolism, is seen to track the breath ethanol. Acetic acid, a possible secondary product of this metabolism, was detected in the exhaled breath, but was shown to largely originate in the oral cavity. Breath acetone was seen to increase over the long period of measurement due to the depletion of nutrients. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of Calixarenes on Chromatographic Separation of Benzene or Uracil Derivatives

The addition of calix[4]arenes to MeCN/H₂O or MeOH/MeCN/THF/H₂O mobile phases improves LC separation of benzene or uracil derivatives on Separon SGX C18 or Separon SGX NH₂ supports. Structure of the calixarenes and their host–guest supramolecular complexes with the analytes are discussed in context of the LC separation.     

Use of tin as a surfactant material for the growth of thin silver films on silicon oxide

In this letter, we report on the use of tin as an effective surfactant material for silver growing on silicon oxide. We observed that submonolayers of Sn pre-deposited on SiO₂ result in earlier film coalescence and formation of smoother Ag layers. We suggest that Sn atoms reduce the Ag-adatom mobility resulting in experimentally observed increased island density and decreased film roughness. Angle-resolved X-ray photoelectron spectroscopy reveals that Sn remains under the Ag layer giving circumstantial evidence that at later stages of Ag film growth Sn does not influence the interlayer transport.     

A Promiscuous Halogenase for the Derivatization of Flavonoids

Halogenation often improves the bioactive properties of natural products and is used in pharmaceutical research for the generation of new potential drug leads. High regio- and stereospecificity, simple reaction conditions and straightforward downstream processing are the main advantages of halogenation using enzymatic biocatalysts compared to chemical synthetic approaches. The identification of new promiscuous halogenases for the modification of various natural products is of great interest in modern drug discovery. In this paper, we report the identification of a new promiscuous FAD-dependent halogenase, DklH, from Frankia alni ACN14a. The identified halogenase readily modifies various flavonoid compounds, including those with well-studied biological activities. This halogenase has been demonstrated to modify not only flavones and isoflavones, but also flavonols, flavanones and flavanonols. The structural requirements for DklH substrate recognition were determined using a feeding approach. The homology model of DklH and the mechanism of substrate recognition are also proposed in this paper.     

Stable Carbenes as Structural Components of Partially Saturated Sulfur-Containing Heterocycles

Recently, an unusual elongation of the C-S bond was observed experimentally for some sulfur-containing heterocycles. Using a superior ab initio (SCS-MP2/cc-pVTZ) level of theory, we showed that the phenomenon can be explained by a contribution of a donor–acceptor adduct of a carbene with an unsaturated ligand. One may achieve further elongation of the C-S bond, eventually turning it to a coordinate one, by increasing the stability of each part of the system as, e.g., in the utmost case of spiro adducts with Arduengo carbenes. The effect of carbene stability was quantified by employing the isodesmic reactions of carbene exchange.