Ethylene Bridge Research Articles

Intracellular interactions of serum-derived C3 in human B cells – Regulation of gene transcription

For the first time combretastatins were isolated from African willow tree Combretum Caffrum. Subsequent studies have shown the impact of combretastatin A4 phosphate, a water-soluble prodrug, on endothelial cells in tumor vascular system. The same effect was not observed in the vascular system. This selectivity is associated with combretastatins mechanism of action: binding to colchicine domain of microtubules, which affects the cytoskeleton functionality of immature endothelial cells. At the same time, combretastatins directly induce cell death via apoptosis and/or mitotic catastrophe pathways. The combination of both elements makes combretastatin an anticancer compound of high efficiency.The cis-configuration is crucial for its biological activity. To date, many derivatives were synthesized. The attempts to resolve spontaneous isomerization to less active trans-stilbene derivative are still in progress. This issue seems to be overcome by incorporation of the ethene bridge with heterocyclic moiety in combretastatins structure. This modification retains the cis-configuration and prevents isomerization. Nevertheless, combretastatin A4 phosphate disodium is still the most potent compound of this group.The combination therapy, which is the most effective treatment, includes combretastatin A4 phosphate (CA4P) and conventional chemotherapeutics and/or radiotherapy. CA4P is relatively well tolerated giving adverse events of moderate severity, which includes: nausea, vomiting, headache, and tumor pain. The aforementioned effects subside on the day of drug administration or on the following day.

Resveratrol: A Double-Edged Sword in Health Benefits.

Resveratrol (3,5,4′-trihydroxy-trans-stilbene) belongs to polyphenols’ stilbenoids group, possessing two phenol rings linked to each other by an ethylene bridge. This natural polyphenol has been detected in more than 70 plant species, especially in grapes’ skin and seeds, and was found in discrete amounts in red wines and various human foods. It is a phytoalexin that acts against pathogens, including bacteria and fungi. As a natural food ingredient, numerous studies have demonstrated that resveratrol possesses a very high antioxidant potential. Resveratrol also exhibit antitumor activity, and is considered a potential candidate for prevention and treatment of several types of cancer. Indeed, resveratrol anticancer properties have been confirmed by many in vitro and in vivo studies, which shows that resveratrol is able to inhibit all carcinogenesis stages (e.g., initiation, promotion and progression). Even more, other bioactive effects, namely as anti-inflammatory, anticarcinogenic, cardioprotective, vasorelaxant, phytoestrogenic and neuroprotective have also been reported. Nonetheless, resveratrol application is still being a major challenge for pharmaceutical industry, due to its poor solubility and bioavailability, as well as adverse effects. In this sense, this review summarized current data on resveratrol pharmacological effects.

Effect of chalcogen substitution on aqueous dispersions of poly(3,4-ethylenedioxythiophene)s:poly(4-styrenesulfonate) and their flexible conducting films

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is a hotspot among current researched conducting polymers and its conductivity could be significantly enhanced by post-treatment with dimethyl sulphoxide (DMSO). In this work, five S and Se analogues of 3,4-ethylenedioxythiophene (EDOT) were synthesized, and chemically oxidative polymerized (COP) to obtain corresponding free-standing films of Poly(3,4-ethylenedioxythiophene)s:poly(4-styrenesulfonate) (PEDOTs:PSS). The effect of chalcogen substitution on the physicochemical properties and conductive performances of PEDOT:PSS film have been demonstrated. In contrast to the conductivities about 10−2–10−1 S cm−1 for PEDOT:PSS and poly(3,4-ethylenedioxyselenophene):poly(4-styrenesulfonate) (PEDOS:PSS), other PEDOTs:PSS films had the conductivities about 10−4–10−5 S cm−1. The conductive enhancement effect of DMSO second-doping is suitable for PEDOTs:PSS films except the all-sulfur analogs of PEDOT:PSS (PEDTT:PSS and PEDTS:PSS), and the critical role of the presence of the O atoms in the ethylene bridges and the S atom in the thiophene ring has been illustrated. This work may help understand the structure-performance relationship of PEDOT family and the further development of PEDOTs in areas where the PEDOT seems monotonous and the high conductivity is not necessary, such as antistatic coating, anticorrosive coating, multi-colored electrochromics and so on.

New iridal-type triterpenoid derivatives with cytotoxic activities from Belamcanda chinensis

Eight new iridal-type triterpenoid derivatives, including two noriridals with ether bridge (1–2); two iridals lactone (3–4), four monocyclic iridals (5–8), together with five known iridals (9–14) were identified from the rhizome of Belamcanda chinensis. Their structures were elucidated on the basis of comprehensive spectroscopic methods and electronic circular dichroism (ECD) calculations. Bioassay results showed that belamcanoxide B (1) exhibited moderated cytotoxic activities against HCT-116 and MCF-7 cell lines with IC50 values of 5.58 and 3.35 μM.

Theoretical and experimental approach to the investigation of hyperpolarizability and charge transfer characteristics of NLO active 2′,3,4,4′,5-pentamethoxy chalcone with silver atoms adsorbed

Organic crystals of 2′,3,4,4′,5-pentamethoxy chalcone (PMC), grown by slow evaporation technique, are subjected to spectroscopic and nonlinear optical analyses. The experimental and theoretical vibrational spectra confirm that the charge-transfer interaction between the methoxy group and phenyl ring through the ethylenic bridge of the PMC molecule must be responsible for the simultaneous IR and Raman activation of C=C stretching and ring modes. The Natural Bond Orbital (NBO) and Atoms In Molecules (AIM) calculations verify the presence of intramolecular hydrogen bonding in the molecule. The large NLO efficiency predicted for PMC is confirmed for the first time by powder SHG efficiency experiment by Kurtz and Perry, while the third order nonlinearity is measured by means of open-aperture Z-scan technique. From the results, the use of PMC for nonlinear optical applications is suggested. The Surface Enhanced Raman Scattering (SERS) spectral investigations have been performed to obtain the adsorption geometry of PMC on the silver surface. Density functional theory at B3LYP/SDD level has been used to compute energies of different configurations of silver adsorbed-PMC to find their stability, optimized geometry of the most stable configuration, and for characterizations including vibrational, NBO and hyperpolarizability analyses.

IMMOBILIZATION OF COBALT DISULFOPHTHALOCYANINATE ONTO POLYMETHYLOLACRYLAMIDE

Different character of usage the porphyrins and their analogs immobilized on carrier polymers stimulates an increased interest in the synthesis and research of physico-chemical properties of porphyrin-polymer immobilizates. In this paper the peculiarities of a synthesis of water-soluble polymer systems containing cobalt disulfophthalocyaninate with the components of a different ratio are described. The methylolation reaction of polyacrylamide to immobilize cobalt disulfophthalocyaninate onto water-soluble carrier polymer has been carried out. It is known that heating polymethylolacrylamide or its solutions leads to the formation of three-dimensional structures with ether and methylene bridges. Therefore, initially the conditions for the preparation of polymethylolacrylamide with preservation of its water solubility were selected. It was found to obtain a water-soluble polymethylolacrylamide, it is necessary that the initial concentration of polyacrylamide in water did not exceed 2% by weight. The immobilization of phthalocyanine metal complex onto the modified polyacrylamide was carried out in two ways. The first is the interaction of the phthalocyanine metal complex with methylated polyacrylamide. The second is functionalization of polyacrylamide and the immobilization of phthalocyaninate metal complex onto the polymer in one-step. The introduction conditions of the cobalt disulfophthalocyaninate introduced influenced the formation of cross-linked structures in the synthesized samples. The introduction of macroheterocycle as a powder was found to promote the formation of insoluble compounds in aqueous media. Therefore, phthalocyanine metal complex was introduced into the system as 1% aqueous solution. The immobilization of the phthalocyanine metal complex onto a carrier polymer has been realized through the formation of hydrogen bonds between the methylol groups of polymethylolacrylamide and sulfo groups of the phthalocyanine metal complex and it was due to coordination interaction between the functional groups of the polymer and metallophthalocyanine as well. The amount of bound cobalt disulfophthalocyanine in the samples was determined by the electronic absorption spectra of the solutions of immobilized phthalocyanine metal complex onto the polymer. The mass content of immobilized cobalt disulfophthalocyaninate onto the polymer in the samples obtained by one-step is greater than in case of the samples obtained in two steps, the ratio of the initial reagents being the same.

Vibrational spectroscopy and X-ray study of three stilbene dyes combined with DFT calculations

Stilbene and its derivatives have a wide application in materials science and biomedical investigations where they are used as the active optical medium or bioactive agents. To provide these researches with new knowledge about stilbenes properties we have performed the structural and spectroscopic analysis of three amino derivatives of trans-stilbene. The DFT calculations in hybrid B3LYP version employing 6-31G (d,p) basis set were used to support the experimental results. The calculated optimized geometries together with the crystal structure obtained from X-ray analysis indicate that all three molecular structures include practically planar stilbene moiety with almost coplanar amino group. The inversion center was revealed in the structure of 4,4′-diaminostilbene. The Raman and IR spectra were registered for solid state in the range of 150–3500 and 500-3500 cm−1, respectively. On the basis of good agreement between the computed frequencies and experimental ones, the thorough vibrational assignment was made. The vibrations of phenyl rings, ethylenic bridge and amino (dimethylamino) group are discussed in detail. The main features of vibrational spectra are revealed for the considered stilbene dyes.

Generalized two-dimensional correlation infrared spectroscopy to reveal the mechanisms of lignocellulosic biomass pyrolysis

As the initial stage of combustion, pyrolysis plays a significant role in the combustion of biomass, a typical solid fuel that contains higher volatile contents than other solid fuels. To better understand the pyrolysis mechanism, we herein employed generalized two-dimensional correlation infrared spectroscopy (2D-PCIS) to analyze the functional group evolution in bamboo chars between 250 and 600 °C, and by combination of the volatile release properties, the biomass pyrolysis process mechanism was speculated. We found that below 250 °C, the hydrogen bonding network within the biomass macromolecular structure was broken, while at 250–300 °C, the branched structures were broken during hydration and decarboxylation reactions, resulting in the formation of H2O, acetic acids, and CO2. The subsequent formation of various phenols between 300 and 350 °C mainly originated from rupture of the ether bridges in the lignin structure. In addition, molecular rearrangement of the intermediates from the decomposition of holocellulose resulted in aromatic ring formation. Interestingly, analysis by 2D-PCIS demonstrated that the aromatic rings bearing adjacent substituents easily formed double active sites following breakage of the branched structures. These structures then easily produced fused ring systems below 400 °C, while dehydrogenation and polycondensation at > 400 °C promoted the formation of fused rings from aromatic rings without adjacent substituents.

Effects of Sulfuric Acid on the Curing Behavior and Bonding Performance of Tannin⁻Sucrose Adhesive.

The development of biomaterials-based adhesives is one of the main research directions for the wood-based material industry. In previous research, tannin and sucrose were used as adhesive to manufacture particleboard. However, the reaction conditions need to be optimized. In this study, sulfuric acid was added to the tannin–sucrose adhesive as a catalyst to improve the curing process. Thermal analysis, insoluble mass proportion, FT-IR, and solid state 13C NMR were used to investigate the effects of sulfuric acid on the curing behavior of tannin and sucrose. Thermal analysis showed weight loss and endotherm temperature reduced from 205 and 215 to 136 and 138 °C, respectively, by adding sulfuric acid. In case of the adhesive with pH = 1.0, the insoluble mass proportion achieved 81% at 160 °C, which was higher than the reference at 220 °C. FT-IR analysis of the uncured adhesives showed that adding sulfuric acid leads to hydrolysis of sucrose; then, glucose and fructose converted to 5-hydroxymehthylfurfural (HMF) and levulinic acid. Dimethylene ether bridges were observed by FT-IR analysis of the cured adhesives. The results of solid state 13C NMR spectrum indicated that 5-HMF participated in the curing process and formed methylene bridges with the C8 position of the resorcinol A-rings of tannin, whereas dimethylene ether bridges were detected as a major chemical chain of the polymer. Lab particleboards were produced using 20 wt % resin content at 180 °C and 10 min press time; the tannin–sucrose adhesive modified with sulfuric acid to pH = 1.0 exhibited better performance than the unmodified tannin–sucrose adhesive; the properties of the boards fulfilled the requirement of Japanese Industrial Standard (JIS) A5908 type 15.

Chiral Transmission to Cationic Polycobaltocenes over Multiple Length Scales Using Anionic Surfactants.

Chiral polymers are ubiquitous in nature, and the self-assembly of chiral materials is a field of widespread interest. In this paper, we describe the formation of chiral metallopolymers based on poly(cobaltoceniumethylene) ([PCE] n+), which have been prepared through oxidation of poly(cobaltocenylethylene) (PCE) in the presence of enantiopure N-acyl-amino-acid-derived anionic surfactants, such as N-palmitoyl-l-alanine (C16-l-Ala) and N-palmitoyl-d-alanine (C16-d-Ala). It is postulated that the resulting metallopolymer complexes [PCE][C16-l/d-Ala] n contain close ionic contacts, and exhibit chirality through the axially chiral ethylenic CH2-CH2 bridges, leading to interaction of the chromophoric [CoCp2]+ units through chiral space. The steric influence of the long palmitoyl (C16) surfactant tail is key for the transmission of chirality to the polymer, and results in a brushlike amphiphilic macromolecular structure that also affords solubility in polar organic solvents (e.g., EtOH, THF). Upon dialysis of these solutions into water, the hydrophobic palmitoyl surfactant substituents aggregate and the complex assembles into superhelical ribbons with identifiable "handedness", indicating the transmission of chirality from the molecular surfactant to the micrometer length scale, via the macromolecular complex.

Influence of Acetaldehyde Induction on Monomeric and Polymeric Polyphenols in Wine using the Polyphenol/Protein-binding Model

Polyphenols make a substantial contribution to the sensory properties of wine, and their evolution is affected by the acetaldehyde present during fermentation and ageing. In this work, five typical monomeric phenolic standards and three different polymeric flavanol fractions separated from wine were tested for polyphenol/protein binding by means of circular dichroism measurement and fluorescence spectrum assay in the presence or absence of acetaldehyde, and the formation of new oligomeric compounds linked by ethyl bridges was observed through HPLC-MS analyses. The results show that the protein-binding ability of these monomers was in the order of gallic acid > caffeic acid > quercetin > (+)-catechin > (-)-epicatechin, while acetaldehyde exerted a stronger effect on (+)-catechin and (-)-epicatechin monomers. Moreover, different wine fractions had different responses when reacted with proteins with the participation of acetaldehyde, while the polymeric proanthocyanidins produced the largest value (84.67%) of the salivary protein precipitation index and the strongest fluorescence-quenching effect.

Discovery, Biosynthesis, and Heterologous Production of Streptoseomycin, an Anti-Microaerophilic Bacteria Macrodilactone

Streptoseomycin (1), which is a rare macrodilactone with potent activities against microaerophilic bacteria, featuring a pentacyclic 5/14/10/6/6 ring system together with an ether bridge, was characterized by a combination of spectroscopic method and X-ray analysis from a marine Streptomyces seoulensis. Sequencing and characterization of a ∼76-kb biosynthetic gene cluster led to the proposition of the biosynthetic pathway of 1. Heterologous expression of the gene cluster using a BAC vector in Streptomyces chartreusis 1018 led to the successful production of 1.

Properties of Sol–Gel Derived Thin Organoalkylenesiloxane Films

We have prepared film-forming solutions for the growth of dense and porous thin organoalkylenesiloxane (OAS) films based on copolymers of methyltrimethoxysilane and 1,2-bis(trimethoxysilyl)ethane (BTMSE) by a sol–gel process. The chemical composition and microstructure of the OAS films have been studied by IR spectroscopy and spectral ellipsometry in relation to the mole fraction of BTMSE and the water: methoxy groups ratio in solution. The results demonstrate that partial substitution of ethylene bridges for silicon–oxygen bonds in OAS leads to distortion of the regular ladder-like structure characteristic of polymethylsilsesquioxane films and the presence of residual silanol groups, which causes an increase in the dielectric permittivity k of the matrix material. The relative porosity in porous OAS films produced via evaporationinduced self-assembly has been shown to be determined by not only the amount of surfactant added but also the presence of a sufficient amount of silanol groups, participating in the attachment of surfactant molecules, in the matrix copolymer solution. In this connection, an important factor determining the structure of the OAS matrix and its pore structure is control over the amount of water involved in the cohydrolysis process. It has been shown that the samples with a relative porosity of 38% prepared from a film-forming solution containing 47 mol % BTMSE (m = 0.7) and 30 wt % surfactant have k ≈ 2.3 and are potentially attractive materials for use as insulators in integrated circuits.

2 H-1,2,3-Triazole-Based Dipeptidyl Nitriles: Potent, Selective, and Trypanocidal Rhodesain Inhibitors by Structure-Based Design.

Macrocyclic inhibitors of rhodesain (RD), a parasitic cysteine protease and drug target for the treatment of human African trypanosomiasis, have shown low metabolic stability at the macrocyclic ether bridge. A series of acyclic dipeptidyl nitriles was developed using structure-based design (PDB ID: 6EX8 ). The selectivity against the closely related cysteine protease human cathepsin L (hCatL) was substantially improved, up to 507-fold. In the S2 pocket, 3,4-dichlorophenylalanine residues provided high trypanocidal activities. In the S3 pocket, aromatic residues provided enhanced selectivity against hCatL. RD inhibition ( Ki values) and in vitro cell-growth of Trypanosoma brucei rhodesiense (IC50 values) were measured in the nanomolar range. Triazole-based ligands, obtained by a safe, gram-scale flow production of ethyl 1 H-1,2,3-triazole-4-carboxylate, showed excellent metabolic stability in human liver microsomes and in vivo half-lives of up to 1.53 h in mice. When orally administered to infected mice, parasitaemia was reduced but without complete removal of the parasites.

Installation of the Ether Bridge of Lolines by the Iron- and 2-Oxoglutarate-Dependent Oxygenase, LolO: Regio- and Stereochemistry of Sequential Hydroxylation and Oxacyclization Reactions

The core of the loline family of insecticidal alkaloids is the bicyclic pyrrolizidine unit with an additional strained ether bridge between carbons 2 and 7. Previously reported genetic and in vivo biochemical analyses showed that the presumptive iron- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, LolO, is required for installation of the ether bridge upon the pathway intermediate, 1-exo-acetamidopyrrolizidine (AcAP). Here we show that LolO is, in fact, solely responsible for this biosynthetic four-electron oxidation. In sequential 2OG- and O2-consuming steps, LolO removes hydrogens from C2 and C7 of AcAP to form both carbon–oxygen bonds in N-acetylnorloline (NANL), the precursor to all other lolines. When supplied with substoichiometric 2OG, LolO only hydroxylates AcAP. At higher 2OG:AcAP ratios, the enzyme further processes the alcohol to the tricyclic NANL. Characterization of the alcohol intermediate by mass spectrometry and nuclear magnetic resonance spectroscopy shows that it is 2-endo-hydroxy-1-exo-acetamidopyrrolizidine (2-endo-OH-AcAP). Kinetic and spectroscopic analyses of reactions with site-specifically deuteriated AcAP substrates confirm that the C2–H bond is cleaved first and that the responsible intermediate is, as expected, an FeIV–oxo (ferryl) complex. Analyses of the loline products from cultures fed with stereospecifically deuteriated AcAP precursors, proline and aspartic acid, establish that LolO removes the endo hydrogens from C2 and C7 and forms both new C–O bonds with retention of configuration. These findings delineate the pathway to an important class of natural insecticides and lay the foundation for mechanistic dissection of the chemically challenging oxacyclization reaction.

Two Chemically Stable Cd(II) Polymers as Fluorescent Sensor and Photocatalyst for Aromatic Dyes.

Two new 2D Cd(II)-based coordination polymers (CPs), viz. [Cd2(H2L)2(2,2’-bipy)2] (1) and [Cd(L)0.5(phen)·0.5H2O] (2), have been constructed using ethylene glycol ether bridging tetracarboxylate ligand 5,5′(4,4′-phenylenebis(methyleneoxy)) diisophthalic acid (H4L). Both CPs behaved as profound fluorescent sensor for Fe3+ ion and nitro-aromatics (NACs), specifically 2,4,6-trinitrophenol (TNP). The stability at elevated temperature and photocatalytic behaviors of both 1 and 2 for photo-decomposition of aromatic dyes have also been explored. An attempt has been made to explore the plausible mechanism related with the decrease in fluorescence intensity of 1 and 2 in presence of NACs using theoretical calculations. Additionally, the probable mechanism of photo catalysis by 1 and 2 to photo-degrade aromatic dyes has been explained using density of states (DOS) calculations.

Synthesis of ENA Nucleotides and ENA Oligonucleotides.

2'-O,4'-C-Ethylene-bridged nucleic acid (ENA) is a sugar-modified oligonucleotide with an ethylene bridge between the 2'-oxygen and 4'-carbon of ribose. ENA not only has as high binding affinity to complementary RNA as conventional bridged/locked nucleic acid, but also has much higher nuclease resistance in plasma, which makes it a promising candidate for antisense therapeutics. This unit presents detailed protocols for the synthesis and characterization of ENA nucleosides and oligonucleotides. © 2018 by John Wiley & Sons, Inc.

6-(2-Morpholinoethyl)-thiazolo[3,2-a]pyrimidin-5-one: A novel scaffold for the synthesis of potential PI3kα inhibitors

The present study involves the development of certain thiazolo[3,2-a]pyrimidin-5-ones linked through an ethylene bridge to various amines. The newly synthesized compounds 4–6(a–c) were subjected to in vitro anticancer evaluation using NCI antitumor screening. The target compounds showed observed activity against Renal UO-31 cancer cell line with cell growth promotion 52.72–64.52%. COMPARE analyses revealed compounds 4a and 4b exhibiting high correlation levels with rapamycin (mTOR inhibitor). Kinase assays were performed for compounds 4a and 4b on mTOR and structurally-related PI3Kα. They displayed moderate activity against PI3Kα with IC50 values of 120 and 151 μM, respectively. Compounds 4a and 4b could thus be considered as a promising leading scaffold for further development of potential PI3Kα inhibitors.

The Endeavor of Diarylethenes: New Structures, High Performance, and Bright Future

AbstractPhotochromism is a term that describes the photoreversible isomerization between two different states or isomers with distinct performances. Among all the photochromic molecule family, diarylethene is considered one of the most popular star molecules on account of its fast photoresponsibility, excellent thermal stability, fatigue resistance, high photoreaction quantum yield, and conversion ratio as well as good performances in both solution and solid phases. In the past decades, the development of diarylethene is witnessed in molecule design, solution applications, surface/interface assembly, bulky crystals and polymers, optic‐electronic devices fabrication, and biotechnology. This review mainly focuses on the latest development of diarylethenes in recent five years and commences with the newly designed molecular structures with functional ethene bridges and aryl moieties. The application of diarylethenes in materials science, soft materials, molecular data processing, and biomaterials, is further discussed in prospect. A brief summary is given in the end of the review together with some perspectives.

Ground State versus Excited State: Discrepancy in Electronic Communication in a Series of meso–meso Two‐Atom‐Bridged Diporphyrins

The focal point of this work is the photophysical characterization of three meso-meso two-atom-bridged diporphyrins. Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/nanosecond transient absorption spectroscopy revealed the discrepancy in electronic communication in a series of meso-meso two-atom-bridged porphyrins in the ground state and in the excited state. In the ground state, the azo bridge facilitates the strongest electronic communication between the two porphyrins. In the excited state, however, the ethene bridge induces the strongest coupling, followed by the imine and azo bridges.