Effect ofβ-cyclodextrin complexation on the photohaemolitic activity induced by Ketoprofen and Naproxen sensitization

Red blood cell lysis photosensitized by two non-steroidal anti-inflammatory drugs Naproxen (NAP) and Ketoprofen (KPF) was investigated in the presence of -cyclodextrin (-Cyd). The photohaemolysis was inhibited by the addition of -Cyd both for NAP and, to a lesser extent, for KPF. The protective action was found only in a restricted range of concentration of -Cyd. Higher amounts of -Cyd interfered with the resistance of the cell to the osmotic shock induced by the photosensitization process. The complexing action of -Cyd was ascertained through UV-vis absorption spectroscopy, induced circular dichroism and emission spectroscopy.The isolated complexes Naproxen--Cyd (NAP--Cyd) and Ketoprofen--Cyd (KPF--Cyd) were found to protect from the photosensitized membrane damage induced by the two drugs, even if it occurred only in a limited range of concentration. This suggests a valid tool in alleviating thein vitro phototoxic consequences caused by these compounds, even if care has to be taken in therapeutic administration due to the presence of the uncomplexed -Cyd.     

Mechanism of membrane interaction and disruption by α-synuclein

Parkinson's disease is a common progressive neurodegenerative condition, characterized by the deposition of amyloid fibrils as Lewy bodies in the substantia nigra of affected individuals. These insoluble aggregates predominantly consist of the protein α-synuclein. There is increasing evidence suggesting that the aggregation of α-synuclein is influenced by lipid membranes and, vice versa, the membrane integrity is severely affected by the presence of bound aggregates. Here, using the surface-sensitive imaging technique supercritical angle fluorescence microscopy and F?rster resonance energy transfer, we report the direct observation of α-synuclein aggregation on supported lipid bilayers. Both the wild-type and the two mutant forms of α-synuclein studied, namely, the familiar variant A53T and the designed highly toxic variant E57K, were found to follow the same mechanism of polymerization and membrane damage. This mechanism involved the extraction of lipids from the bilayer and their clustering around growing α-synuclein aggregates. Despite all three isoforms following the same pathway, the extent of aggregation and their effect on the bilayers was seen to be variant and concentration dependent. Both A53T and E57K formed cross-β-sheet aggregates and damaged the membrane at submicromolar concentrations. The wild-type also formed aggregates in this range; however, the extent of membrane disruption was greatly reduced. The process of membrane damage could resemble part of the yet poorly understood cellular toxicity phenomenon in vivo.     

Regioisomeric control induced by DABCO coordination to rotatable self-assembled bis- and tetraporphyrin α,γ-cyclic octapeptide dimers

The design and synthesis of two α,γ-cyclic octapeptides decorated with one and two Zn-porphyrin units in their periphery is described. In nonpolar organic solvents the α,γ-cyclic octapeptides quantitatively self-assemble into Zn-bis- or -tetraporphyrin architectures that could act as molecular tweezers. The self-assembly process, however, is not regioselective and affords a mixture of different regioisomers that are involved in chemical exchange processes. The regioisomers with the Zn-porphyrin units positioned in register with respect to each other are proposed to be the less abundant species in the solution mixture. It has been demonstrated that the coordination of 1,4-diazabicyclo[2.2.2]octane (DABCO) to the supramolecular bis- or tetraporphyrin tweezers is an effective way to achieve regioisomeric control of the self-assembled mixture of dimers. Thus, DABCO functions as an external molecular trigger and, when used under strict stoichiometric control with respect to the Zn-porphyrin units, provokes the exclusive formation of self-assembled dimers with a cofacial arrangement of Zn-porphyrin units through the formation of sandwich-type complexes. The use of excess DABCO fragments the sandwich complexes and affords open dimers of high stoichiometry with DABCO molecules axially monocoordinated to the Zn-porphyrin units, probably as a regioisomeric mixture. In the case of Zn-tetraporphyrin tweezers, the ditopic coordination of DABCO at the two binding sites shows a moderate positive cooperativity factor, αP=5. These assemblies have potential applications as light-induced energy and electron-transfer switches regulated by DABCO coordination; such applications would require the introduction of additional chromophores in the cyclic peptide scaffold.     

Ethylene–Norbornene Copolymerization by Rare-Earth Metal Complexes and by Carbon Nanotube-Supported Metallocene Catalysis

E–N copolymerization with a number of half-sandwich rare-earth metal compounds [M(η5-C₅Me₄SiMe₂R)(η1-CH₂SiMe₃)₂(L)] (M = Sc, Y, Lu) has been achieved. Mainly atactic alternating E N copolymers are obtained with all catalytic systems. Interestingly, copolymers arising from [Sc(η5-C₅Me₄SiMe₂C₆F₅)(η¹-CH₂SiMe₃)₂(THF)]/[/[Ph₃C][B(C₆F₅)₄] possess narrower molar mass distributions than those from [Sc(η⁵-C₅Me₄SiMe₃)(η¹-CH₂SiMe₃)₂(THF)] / [Ph₃C][B(C₆F₅)₄]. In addition, homogeneous surface coating of multi-walled carbon nanotubes is accomplished for the first time by in situ E–N copolymerization as catalyzed by rac-Et(Ind)₂ZrCl₂/MMAO-3A anchored onto the carbon nanotube surface. The copolymerization reaction allows for the destructuration of the native nanotube bundles. The relative quantity of E N copolymer can be tuned up as well as the norbornene content in the formed copolymers and accordingly their glass transition temperature. By melt blending with an ethylene-vinyl-co-acetate copolymer (27 wt.-% vinyl acetate comonomer) matrix, high performance polyolefinic nanocomposites are obtained.     

Structure, Magnetism and Spin Coupling Mechanism of Cyano-Bridged LnIII–FeIII Binuclear Metal Complexes

A series of binuclear metal complexes [Ln(L)₄(H₂O)₃Fe(CN)₆]·nH₂O (Ce(1), Pr(2), Nd(3), Sm(4), Eu(5), Gd(6), Tb(7), Dy(8), Er(9), L=2-pyrrolidinone) were prepared and the X-ray crystal structures of complexes 4, 6, and 8 were determined. All the compounds consist of an Ln–CN–Fe unit, in which an octahedral coordinated Fe^III is bridged to an Ln^III ion located in square antiprism environment by a cyano group. The magnetic properties of 3, 4, 5, 6, 7, 9 show an overall antiferromagnetic behavior. The fitting to the experimental magnetic susceptibilities of complex 6 gave g=1.99, J=0.735 cm^–1, zJ=–0.080 cm^–1 on the basis of a binuclear spin system (S _Gd=7/2, S _Fe=1/2), revealing a ferromagnetic intra-molecular Gd–Fe interaction and an antiferromagnetic inter-molecular interaction. Results on the quantum chemical density functional theory (DFT) calculation for 6 showed that the calculated magnetic coupling constant is 8.1 cm^–1, supporting the occurrence of weak ferromagnetic intra-molecular interaction in 6. The spin density maps for 6 in the high spin ground state and broken symmetry state were obtained, and the spin–spin coupling mechanism is discussed.     

GC–MS analysis and anti–microbial activity of Prunella vulgaris L. extracts

In this study, the chemical composition of the methanol, hexane and ethyl acetate extracts of Prunella vulgaris L. were investigated by gas chromatography–mass spectrometry (GC–MS) method. 2-hydroxy-5-methylbenzaldehyde (15.70%), linolenic acid (45.50%) and icosane (16.24%) were found to be the most abundant in methanol, hexane and ethyl acetate extracts, respectively. Following the determination of chemical components of the Prunella vulgaris L. extracts, their anti–microbial activities against certain human pathogenic bacteria were tested and minimal inhibitory concentrations (MIC) were determined. While some extracts of Prunella vulgaris L. show anti–microbial activity well above the standards (penicillin and tetracycline), it was determined that in general all the extracts showed good anti–microbial activity against these pathogenic bacteria.     

Radiation polymerization and copolymerization of fluorinated acrylates and methacrylates induced by γ-rays

Fluorinated acrylates and methacrylates radiolyzed at 77 K polymerize upon heating in the range from the glass-transition to the melting temperature. In the case of acrylates, the temperature range of postradiation polymerization increases by more than 100 K with the increasing chain length of the perfluorinated substituent from C₂F₄ to C₈F₁₇. The introduction of perfluorinated substituents into methacrylate molecules makes it possible to obtain them in the glassy state and to carry out low-temperature postradiation polymerization, in contrast to their hydrocarbon analogues. The termination rate constant of the polymerization of fluorinated methacrylates has a lower value as compared to conventional methacrylates. The formation of crosslinked structures is suppressed during the copolymerization of fluorinated acrylates with methacrylates. The ESR spectra of growing polymer radicals of fluorinated acrylic ∼CH₂C^·H(COOCH₂C₆F₁₃)∼ and methacrylic CH₂C^·(CH₃)(COOCH₂C₂F₄H)∼ monomers have been identified.     

Hydroxy lactones with the gem-dimethylcyclohexane system – Synthesis and antimicrobial activity

Two new lactones comprising the gem-dimethylcyclohexane ring: 2-chloro-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one and 2-bromo-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one as well as the already known 2-iodo-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one, were obtained from (6,6-dimethylcyclohex-2-en-1-yl)acetic acid. These lactones were used as substrates for the screening of biotransformation by whole cells of nine fungal strains (Fusarium species, Syncephalastrum racemosum and Cunninghamella japonica). Some of these microorganisms (mainly Fusarium species) transformed all three lactones during the hydrolytic dehalogenation into 2-hydroxy-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one. It is worth noting that two microorganisms (Fusarium culmorum and Fusarium scirpi) converted iodolactone with very high enantioselectivity (75.1% and 91.6%, respectively). The (+) isomer of hydroxy lactone was preferred. At the last step the hydroxy lactone obtained during biotransformation was examined for its biological activity against bacteria, yeasts and fungi. It was found that this compound inhibits growth of some tested microorganisms.     

Transformation of Structure and Properties of Vesicles Induced by Transition Metal Ions

This paper proved that octodecyl propylenediamine could form vesicles in pure water and aqueous solution of CuCl2 or Cu（NO3）2. The structure and morphology of vesicles were different when the copper （Ⅱ） salt was added to the solution. The results showed that both the counterions and the ligands had strong influence on the configuration of coordinated structures and packing model in bilayer membrane of vesicles.     

Kinetics and Mechanism of Dechlorination of o-Chlorophenol by Nanoscale Pd／Fe

IntroductionTherehasbeenagrowinginterestintheuseofzero valentironforthetreatmentofchlorinatedor ganiccompounds(COCs)inwaterandgroundwater .Thestudieshavebeenfocusedonsuchcompoundsascarbontetrachloride ,trichloroethene ,pesticidesandtherelatedcompounds[1— 7] .Whenironisincontactwithalessreductivemetalsuchaspalladiumwhosecomplexhasbeenusedtohydrogenatenitroben zene[8] ,themetalcouplecanformgalvaniccells .ThisledtothediscoveryofaPd/Febimetalliccomplexofwhichpalladiumservesasacatalystandironasa…     

Atmospheric-Pressure Plasma Reduction of Metal Cation-Containing Polymer Films to Produce Electrically Conductive Nanocomposites by an Electrodiffusion Mechanism

We describe an atmospheric-pressure plasma process for the reduction of metal cation-containing polymer films to form electrically conductive patterns. Thin films of poly(acrylic) acid (PAA) containing silver ions (Ag⁺) were prepared by mixing the polymer with silver nitrate (AgNO₃) in solution to produce a cross-linked precipitate, homogenizing, and depositing onto a substrate by doctor’s blade. Exposing the Ag–PAA films to a scanning microplasma resulted in reduction of the bulk dispersed Ag⁺ in a desired pattern at the film surface. The processed films were characterized by scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, and current–voltage measurements. The resistances of the patterned features were found to depend on the thickness of the films, the microplasma scan rate, residual solvent in the film, and electric field created between the microplasma and the substrate. Together these results show that the formation of conductive features occurs via an electrodiffusion process where Ag⁺ diffuses from the film bulk to the surface to be reduced by the microplasma.     

Mechanism and Modeling of Emulsion Polymerization: New Ideas and Concepts – 2. Modeling Strategies

Summary: Molecular modeling strategies offer new insights into the mechanism of heterophase polymerization. The capabilities of Brownian dynamic simulations are illustrated by means of studies regarding radical entry and exist as essential steps in emulsion polymerization. Interestingly, the results allow certain generalizations which were not possible with macroscopic deterministic modeling strategies.     

Mechanism and Modeling of Emulsion Polymerization: New Ideas and Concepts – 1. Particle Nucleation

Summary: New experimental data for nucleation in emulsion polymerization prove that the process is heterogeneous in nature so that water-borne oligomers precipitate at the surface of monomer drops. The particle morphology at the early stage of the process is strongly influenced by the initiator concentration. The hydrophilicity of the monomer is less important as methyl methacrylate, styrene, and 4-tert-butyl styrene show similar behaviour.     

Mechanism of simultaneously refolding and purification of proteins by hydrophobic interaction chromatographic unit and applications

The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the chromatographic condition, several denatured proteins can be refolded and separated simultaneously in a single chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative     

Heavy Metal Determination by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) and Direct Mercury Analysis (DMA) and Arsenic Mapping by Femtosecond (fs) – Laser Ablation (LA) ICP-MS in Cereals

A study of the lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) contents in popular cereals was conducted using inductively coupled plasma – mass spectrometry (ICP-MS), direct mercury analysis (DMA), and femtosecond laser ablation – inductively coupled plasma – mass spectrometry (fs-LA-ICP-MS). For Pb, Cd, and As determination, the samples were prepared using microwave digestion, while for Hg, the samples were homogenized and measured by DMA without additional pretreatment. Satisfactory values for all of the quality parameters that include the SD, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and recovery were obtained, clearly validating the analytical techniques used in the current study. Recovery and accuracy measurements were done using rice flour CRM 108-01-002 from Korea Research Institute of Standards and Science (KRISS). All measured concentrations for these elements were lower than the national regulatory guideline values provided by the CODEX Alimentarius and Ministry of Food and Drug Safety. A sample from each group was also selected for an As distribution study within a grain using fs-LA-ICP-MS. As is classified as a first-class carcinogen by the International Agency for Research on Cancer (IARC). For adlay, oats, and barley, As was determined to be primarily distributed in the area where the grain splits, while for foxtail millet, sorghum and corn, As was concentrated in the grain embryo. Also, it was confirmed that the exposure of heavy metals in the diet was negligible due to the low metal concentrations consumed daily in these foods.     

New chiral Mannich adducts of di-tert-butylphenols and a bicyclic imine – Synthesis and antiproliferative activity

Tests of antiproliferative activity of Mannich adducts of aromatic nucleophiles and a chiral bicyclic imine revealed a di-tert-butylphenol derivative as a promising compound for further exploration. To study the influence of substitution pattern and a configuration of stereogenic centers on the inhibition of cancer cell growth, a series of Mannich bases were obtained with a good to high diastereoselectivity from the reaction of the imine and three isomeric di-tert-butylphenols. Six new enantiopure adducts were isolated and fully characterized. Selected derivatives were shown to exhibit an interesting antiproliferative activity comparable to cisplatin.     

Beer clarification by microfiltration — product quality control and fractionation of particles and macromolecules

Beer clarification by microfiltration demands a finely balanced retention of colloidal particulates (yeast cells, chill haze flocs, etc.) and transmission of soluble macromolecules including carbohydrates, proteins, flavour, and colour compounds which give the “whole some” quality of a beer. The required porous transmission of these macromolecular species led to an unavoidable, complex and dynamic in-pore membrane fouling in terms of fouling constituents, formation, structure and kinetics, which are the main obstacles in obtaining an economically viable flux and consistency in permeate quality.This experimental study was carried out with the aims of understanding the dynamic inter-relation between flux, fouling and system selectivity during a cross-flow beer microfiltration process so that an effective operating strategy for flux optimisation could be formulated in conjunction with the parallel objective of good product (permeate) quality control. Tubular ceramic membranes (Ceramem) with nominal pore diameters of 0.2, 0.5, and 1.3 μm were used. Simultaneous measurement of flux and permeate qualities, such as specific gravity and chill haze level enabled identification of the effect of anti-fouling techniques, such as backflushing on transmission of essential beer components and on the filtered beer quality. The experimental evidence lead to an understanding that the drastic flux enhancement achieved by employing backflushing at reversed membrane morphology was associated with enhanced solute transmission which could, without careful control, upset a balanced transmission of essential beer components and the retention of unwanted “chill haze” components. Further operating parameters and varying system configurations were investigated over their effect on both flux performance and system selectivity. These include membrane pore size, filtration temperature, and the addition of an amorphous silica particles as coagulation agent for hydrophilic proteins.     

Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

Capillary electrophoresis (CE )hasrapidlygainedgreatinterestsamongresearchersinmanydifferentfields .Oneoftheseareasistheseparationofsmallionssuchasinorganiccations[1- 9] ,an ions[10 - 16 ] ,andlowMr organicmolecules[17- 2 0 ] .However ,astheseparationofio…     

Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions