Diastereomeric selective effects for growth inhibition of synthesized mini parallel double-stranded peptides on Escherichia coli and Staphylococcus aureus

The synthesis of a series of mini double-stranded peptides containing chiral-x-Phe-y-Phe-peptide residues and the diastereomeric selective effects of these compounds on Escherichia coli NIHJ JC-2 and Staphylococcus aureus FDA 209P growth are described. In the case of bis(y-Phe-x-Phe)-N,N-ethane-1,2-diamine, bis(y-Phe-x-Phe)-N,N-buthane-1,4-diamine, bis(y-Phe-x-Phe)-N,N-hexane-1,6-diamine, and bis(y-Phe-x-Phe)-N,N-dodecane-1,12-diamine, etc., the four configurations, (L-, L-), (D-, L-), (L-, D-) and (D-, D-), where the symbols x- and y- represent optical isomers with L- and D- forms, were used to investigate the relationship between chirality and antibacterial activity. The level of activity increased in the following order: (L-, L-)<(D-, D-)<(L-, D-)<(D-, L-). The data show that (D-, L-) chilarity is more potent than (L-, L-) chilarity. Then, these results suggest that the -y-Phe-x-Phe Phe-sequence in the double-stranded peptide has anti-bacterial activity and the chirality of -y-Phe-x-Phe affects the anti-bacterial activity. Our results show that the uptake by penetration through the membrane of bis(y-Phe-x-Phe)(2)-Spacers is a first step in the expression of anti-bacterial activity. This study provides new insights in the chirality-antibacterial activity relationships of a series of mini double-stranded peptides.     

Diastereomeric selective effects of double-stranded peptides conjugated with -Phe-Phe- residue for growth inhibition and permeability of Ca(2+) on A431, src(ts)NRK, and A549 cells proliferation

Our aim in this study is to elucidate the correlations between inhibition and chirality, especially, diastereomer, against cell proliferation of double-stranded peptides. In previous studies, we reported on the design, synthesis, and chemical properties on a series of novel double-stranded peptides, (y-AA-x-AA)(2)-spacer(S) (AA=amino acid, S=spacer, symbols x and y represent L- or D-forms, and (y-, x-) as represent of the symbol) conjugated with -y-AA-x-AA- and -z-AA-y-AA-x-AA- sequences to a spacer of carbon number n. The inhibition of A431 and src(ts)NRK cells growth by four diastereomers of the N(1),N(12)-bis(y-Phe-x-Phe)dodecanediamines (n=12) increased in the following order: (L-, L-)<(D-, D-)<(L-, D-)<(D-, L-). A similar trend was seen in the order for the activity of (y-AA-x-AA)(2)-spacer(S) with a spacer of carbon number n=2, 3, 4, 5, 6, and 12 against the cell growth inhibition. To understand the mechanism of diasteromer selective cell growth inhibition, the correlations between chirality and cell growth inhibition were investigated from the measurement of the changes in cytosolic Ca(2+) concentration (=[Ca(2+)](c)) of A431 cells. Although less active N(1),N(12)-bis(L-Phe-L-Phe)dodecanediamine increases cytosolic [Ca(2+)](c), more active diasteromers, N(1),N(12)-bis(L-Phe-D-Phe)dodecanediamine and N(1),N(12)-bis(D-Phe-L-Phe)dodecanediamine, decrease cytosolic [Ca(2+)](c) in A431 cell. This study provides diastereomeric effected new insights - this controls the polarity of double-stranded peptides - into the control of tumor cell proliferation and design of the uptake by penetration through the cell membrane of drugs.     

Synthesis, processing and properties of conjugated polymer networks

Despite the diverse research activities focused on the chemistry, materials science and physics of conjugated polymers, the feature of conjugated cross-links, which can provide electronic communication between chains, has received little attention. This situation may be a direct consequence of the challenge to introduce such links while retaining adequate processability. Focusing on recent studies of materials for which charge transport or electrical conductivity data are available, this feature article attempts to present an overview of the synthesis, processing and electronic properties of conjugated polymer networks. For the purpose of this discussion, two distinctly separate architectures-featuring covalent cross-links on the one hand and non-covalent organometallic bridges on the other-are treated in separate sections. The available data indicate that cross-linking can have significant benefits for intermolecular charge transfer if the polymers are carefully designed.     

Synthesis and nonlinear optical absorption properties of two new conjugated ferrocene-bridge-pyridinium compounds

Two electron donor-π-acceptor (D-π-A) chromospheres, with ferrocene as the electron donor and pyridinium as the electron acceptor, were synthesized. The nonlinear optical absorption (NOA) properties in the solution state were investigated by the Z-scan technique. Both compounds exhibited reverse saturable absorption (RSA) and optical limiting effect under nanosecond pulse irradiation.     

Synthesis and photophysical properties of new conjugated fluorophores designed for two-photon-excited fluorescence

[structure: see text] Novel elongated push-push fluorophores (e.g., 9) were synthesized by 2-fold Sonogashira or Wittigminus signHorner reactions. Modulation of the length and topology of the conjugated connectors allows tuning of their photophysical properties. In addition, their photoluminescence can be adjusted by playing on polarity. Derivatives combining enhanced two-photon absorption cross section (sigma2) in the visible red and high fluorescence quantum yield (Phi) have been obtained. Such fluorophores hold promise for nonlinear imaging of biological systems.     

Synthesis and anticancer properties of RGD peptides conjugated to nitric oxide releasing functional groups and abiraterone

A series of analogues of the integrin binding aspartic acid-glycine-arginine (RGD) peptide sequence were synthesised conjugated to nitric oxide (NO) donating functional groups. Also the cytotoxicity of abiraterone, a prostate cancer drug, was explored when it was conjugated in three part constructs to RGD sequences and NO releasing heterocycles. In general the analogues showed integrin binding affinity comparable to RGD reference compounds, and all released NO by the Griess test assay. Two analogues exhibited significant cytotoxic effects against PC3 and MCF7 cell lines.     

Ferrocenes conjugated with thiophene,carbazole, and pyrimidine fragments: Synthesis and properties

Russian Journal of Applied Chemistry - Ferrocenyl-containing chalcones containing π-excessive heterocyclic fragments capable of electrochemical polymerization (carbazole, thiophene,...     

Synthesis and structure of a new zirconium phosphate with double-stranded chains

The zirconium phosphate [Zr(HPO₄)(PO₄)F₂] · 1.5H₂en was prepared, and its structure was determined by X-ray diffraction analysis.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1897–1901, November, 1994.The work was carried out with financial support from SERC (UK) and the National Foundation of Natural Sciences (China).     

Synthesis and properties of two new series of isomeric liquid crystalline polyesters with conjugated double bonds

Two homologous series of flexible main chain liquid crystalline polyesters with isomeric mesogenic groups containing conjugated double bonds, were synthesized and studied by differential scanning calorimetry and optical microscopy. One series (S1) has the p-phenylene-diacryloyloxydibenzoyl moiety as a mesogenic unit. The other (S2) has the terephtaloyl dioxydicinnamoyl moiety as a mesogenic unit. The reactivity of the conjugated double bonds of the p-phenylenediacryloxy unit, at the temperature of mesophase formation, impedes the stability of liquid crystalline mesophases of polymers of series (S1). Two low molecular weight analogues of polymers were also prepared and their properties compared with those of polymers of similar structure. The two model compounds form stable smectic mesophases over a wide range of temperatures, which shows the high mesomorphogenic ability of both mesogenic units.     

Synthesis and optical properties of conjugated dendrimers with unsymmetrical branching

An improved synthetic approach to conjugated monodendrons with unsymmetrical branching structures is reported. Dendrimers containing two or three such conjugated monodendrons are synthesized and their optical properties are studied. Such dendrimers exhibit broad absorptions and very high fluorescence quantum yields, making them promising candidates for applications in molecular-based photonics.     

Synthesis and properties of hyperbranched conjugated porphyrins

[reaction: see text] Hyperbranched conjugated porphyrin arrays were prepared by one-pot Suzuki polycondensation of AB3 and AB3 + C4 approaches.     

Synthesis and properties of conjugated enyne polysulfones

High-molecular-weight polysulfones that contained 1,3-enyne linkages in the polymer backbone were prepared by the reaction of potassium salts of (E)-1,3-bis(3-hydroxyphenyl)-1-buten-3-yne and 4,4′-dihydroxybiphenyl with 4,4′-dihalodiphenylsulfones in DMSO-sulfolane solvent mixtures. The polymers were soluble in methylene chloride and exhibited intrinsic viscosities as high as 0.74 (in DMAC at 30°C) with glass transition temperatures ranging from 179 to 214°C. It was postulated that on heating the polymers would cure via a intramolecular cycloaddition reaction to from a 2-phenylnaphthalene fused ring system along the polymer backbone. Thermal analytical data studies on cured polymer films and investigations of the products obtained from the thermal reactions of model compounds indicated that the primary curing reaction was intermolecular rather than intramolecular in nature. Additional data from testing fabricated composites indicated that the enyne polysulfones have suitable properties for use as high-temperature thermoplastic composite materials.     

Synthesis,characterization, and properties of conjugated binuclear bis-terpyridyl ruthenium complexes

A series of binuclear bis-terpyridyl ruthenium complexes with different substituents were synthesized and characterized by physico-chemical and spectroscopic methods. The UV/Vis and fluorescence spectra indicated that the non-substituted binuclear bis(terpyridyl) ruthenium(II) complex has similar properties to those with electron-donating groups such as methyl and alkoxyl on the organic conjugated bridge units. Furthermore, similar oxidation–reduction potentials were observed according to their electrochemical properties in CH₂Cl₂ solution.     

Synthesis and photophysical properties of tetraphenylethylene-based conjugated dendrimers with triphenylamine core

Two new conjugated dendrimers bearing a tetraphenylethylene moiety as dendrons and triphenylamine as a core have been synthesized through a convergent synthetic strategy using threefold Heck/threefold Sonogashira coupling reaction. These dendrimers showed excellent solubility in common organic solvents and emit light in the blue and violet regions.     

Synthesis and electronic properties of conjugated pentacene dimers

Conjugated pentacene dimers 1-3 were synthesized in two steps from readily available precursors. Noteworthy is the initial step, which assembles five independent fragments to form the carbon-rich molecular framework. Solution-cast films of these materials are air stable. Photocurrent measurements for solution-deposited thin films show that dimer 3 exhibits photoconductive gain >10.     

Synthesis,structural characterization,and immunological properties of carbon nanotubes functionalized with peptides

Carbon nanotubes (NTs) are becoming highly attractive molecules for applications in medicinal chemistry. The main problem of insolubility in aqueous media has been solved by developing a synthetic protocol that allows highly water-soluble carbon NTs to be obtained. As a result, biologically active peptides can be easily linked through a stable covalent bond to carbon NTs. We have demonstrated that a bound peptide from the foot-and-mouth disease virus, corresponding to the 141-159 region of the viral envelope protein VP1, retained the structural integrity and was recognized by monoclonal and polyclonal antibodies. In addition, this peptide-NT conjugate is immunogenic, eliciting antibody responses of the right specificity. Such a system could be greatly advantageous for diagnostic purposes and could find future applications in vaccine delivery.     

Synthesis and properties of novel heat-resistant fluorescent conjugated polymers with bisindolylmaleimide

Novel conjugated polymers with bisindolymaleimide were synthesized via simple metal-free condensation polymerization. The polymers exhibited high glass transition temperatures and decomposition temperatures with considerable luminescent properties.     

Synthesis and properties of C-C conjugated phthalocyanine dimers

Covalently C-C linked Pc-Pc homo-dimers (ortho and meta) were synthesized from their corresponding Pc halide precursors using a Pd-catalyzed homo-coupling reaction. Photophysical data reveal energy transfer between the Pc moieties resulting in the appearance of new red-shift Q-bands that correlate to the planarity and dihedral angle between the subunit.     

Synthesis and photophysical properties of phenothiazine-labeled conjugated dendrimers

A novel class of conjugated dendrimers bearing phenothiazines as peripheral groups and phenylenevinylene-group as a core has been synthesized through the Wittig-Horner reaction in moderate to good yield.     

Synthesis and properties of conjugated hybrid tetrathiafulvalene dimers

The synthesis of new hybrid tetrathiafulvalene (TTF) dimers (11a-c) has been carried out by a Wittig-Horner reaction of the respective phosphonate esters (10a-c) with 2-(tetrathiafulvalenylvinyl)-9, 10-anthraquinone (9) prepared by olefination of formyltetrathiafulvalene (7) and the phosphonium salt of anthraquinone 8. Electrochemical studies show that the dimers 11a-c mainly retain the electrochemical properties of both TTF and the pi-extended TTF components, and most importantly, intramolecular electronic interactions between the two moieties are observed by cyclic voltammetry and Osteryoung square wave voltammetry. Semiempirical PM3 calculations reveal an almost planar geometry for the TTF and the benzene ring connected through the vinyl spacer. These compounds can form stable charge-transfer complexes with 2, 3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) showing a stoichiometry of 1:3 (D:A). Attempts to electrocrystallize the dimeric donors with different counteranions are discussed.