- Chemical enhancement by nanomaterials under X-ray irradiation
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We report here a new phenomenon of dynamic enhancement of chemical reactions by nanomaterials under hard X-ray irradiation. The nanomaterials were gold and platinum nanoparticles, and the chemical reaction employed was the hydroxylation of coumarin carboxylic acid. The reaction yield was enhanced 2000 times over that predicted on the basis of the absorption of X-rays only by the nanoparticles, and the enhancement was found for the first time to depend on the X-ray dose rate. The maximum turnover frequency was measured at 1 × 10-4 s-1 Gy-1. We call this process chemical enhancement, which is defined as the increased yield of a chemical reaction due to the chemical properties of the added materials. The chemical enhancement described here is believed to be ubiquitous and may significantly alter the outcome of chemical reactions under X-ray irradiation with the assistance of nanomaterials.
- Cheng, Neal N.,Starkewolf, Zane,Davidson, R. Andrew,Sharmah, Arjun,Lee, Changju,Lien, Jennifer,Guo, Ting
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- Selective tracking of ovarian-cancer-specific γ-glutamyltranspeptidase using a ratiometric two-photon fluorescent probe
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Real-time tracking of GGT enzymatic activity in human ovarian cancer cells is a reliable method for accurate prediction of cancer diagnosis and management. Here, we report the two-photon ratiometric tracking of GGT activity in cancer cells based on a probe with switchable F?rster resonance energy transfer properties. In the absence of GGT, the designed probe showed two well-resolved emission bands at 461 and 610 nm, corresponding to the 7-hydroxycoumarin donor and BODIPY acceptor, respectively. In contrast, GGT catalyzed cascade reactions including cleavage of the γ-glutamyl group and subsequent aromatic hydrocarbon transfer from the S to N atom increased the distance between the two chromophores, thus decreasing the FRET efficiency, with the recovery of the donor fluorescence at 461 nm. By exploiting this enzyme-triggered ratiometric measurement, successful differentiation of ovarian cancer cells from normal cells with this probe was realized by two-photon fluorescence confocal microscopy.
- Shi, Ben,Zhang, Zhenyu,Jin, Qingqing,Wang, Zhiqiang,Tang, Jie,Xu, Ge,Zhu, Tianli,Gong, Xueqing,Tang, Xinjing,Zhao, Chunchang
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- X-ray and solution structures of CuIIGHK and CuIIDAHK complexes: Influence on their redox properties
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The Gly-His-Lys (GHK) peptide and the Asp-Ala-His-Lys (DAHK) sequences are naturally occurring high-affinity copper(II) chelators found in the blood plasma and are hence of biological interest. A structural study of the copper complexes of these peptides was conducted in the solid state and in solution by determining their X-ray structures, and by using a large range of spectroscopies, including EPR and HYSCORE (hyperfine sub-level correlation), X-ray absorption and 1H and 13C NMR spectroscopy. The results indicate that the structures of [CuII(DAHK)] in the solid state and in solution are similar and confirm the equatorial coordination sphere of NH2, two amidyl N and one imidazole N. Additionally, a water molecule is bound apically to CuII as revealed by the X-ray structure. As reported previously in the literature, [CuII(GHK)], which exhibits a dimeric structure in the solid state, forms a monomeric complex in solution with three nitrogen ligands: NH2, amidyl and imidazole. The fourth equatorial site is occupied by a labile oxygen atom from a carboxylate ligand in the solid state. We probe that fourth position and study ternary complexes of [CuII(GHK)] with glycine or histidine. The CuII exchange reaction between different DAHK peptides is very slow, in contrast to [CuII(GHK)], in which the fast exchange was attributed to the presence of a [CuII(GHK)2] complex. The redox properties of [CuII(GHK)] and [CuII(DAHK)] were investigated by cyclic voltammetry and by measuring the ascorbate oxidation in the presence of molecular oxygen. The measurements indicate that both Cu II complexes are inert under moderate redox potentials. In contrast to [CuII(DAHK)], [CuII(GHK)] could be reduced to Cu I around -0.62 V (versus AgCl/Ag) with subsequent release of the Cu ion. These complete analyses of structure and redox activity of those complexes gave new insights with biological impact and can serve as models for other more complicated CuII-peptide interactions. Copyright
- Hureau, Christelle,Eury, Helene,Guillot, Regis,Bijani, Christian,Sayen, Stephanie,Solari, Pier-Lorenzo,Guillon, Emmanuel,Faller, Peter,Dorlet, Pierre
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- Noncovalent multivalent assembly of jun peptides on a leucine zipper dendrimer displaying fos peptides
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(Chemical Equation Presented) The synthesis and characterization of a new leucine-zipper dendrimer (LZD) is reported that displays four copies of the peptide corresponding to the coiled-coiled dimerization domain of Fos. Circular dichroism spectroscopy, fluorescence titration, and sedimentation equilibrium experiments demonstrate that Fos-LZD can noncovalently assemble four copies of the peptide corresponding to the coiled-coil domain of Jun. This work provides the basis for the future construction of noncovalently assembled multivalent protein assemblies displaying any protein of interest.
- Zhou, Min,Ghosh, Indraneel
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- The effect of potential supramolecular-bond promoters on the DNA-interacting abilities of copper-terpyridine compounds
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Three copper(ii) coordination compounds have been prepared from three different 2,2′:6′,2′′-terpyridine-based ligands, which have been selected to investigate the potential role of supramolecular interactions on the DNA-interacting and cytotoxicity properties of the corresponding metal complexes. Hence, the ligands 4′-((naphthalen-2-yl)methoxy)-2,2′:6′,2′′-terpyridine (Naphtpy) and 4′-((1H-benzo[d]imidazol-2-yl)methoxy)-2,2′:6′,2′′-terpyridine (Bimztpy) have been synthesized from commercially-available 4′-chloro-2,2′:6′,2′′-terpyridine (Cltpy), and their copper(ii) complexes have been obtained by reaction with copper(ii) nitrate. The DNA-interacting abilities of the corresponding compounds [Cu(Cltpy)(H2O)(NO3)2] (1), [Cu(naphtpy)(NO3)(H2O)](NO3)(MeOH) (2) and [Cu(bimztpy)(NO3)(H2O)](NO3) (3) have been investigated using different techniques, and cytotoxicity assays with several cancer cell lines have revealed interesting features, viz. the more efficient complex is 2, which although it does not act as a DNA cleaver, displays the most effective DNA-interacting and cytotoxic properties, compared to 1 and 3.
- Grau, Jordi,Brissos, Rosa F.,Salinas-Uber, Jorge,Caballero, Ana B.,Caubet, Amparo,Roubeau, Olivier,Korrodi-Gregório, Luís,Pérez-Tomás, Ricardo,Gamez, Patrick
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- Simultaneous Fluorescence Imaging Reveals N-Methyl- d -aspartic Acid Receptor Dependent Zn2+/H+ Flux in the Brains of Mice with Depression
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Depression is immensely attributed to the overactivation of N-methyl-d-aspartic acid (NMDA) receptor in the brains. As regulatory binding partners of NMDA receptor, both Zn2+ and H+ are intimately interrelated to NMDA receptor's activity. Therefore, exploring synergistic changes on the levels of Zn2+ and H+ in brains will promote the knowledge and treatment of depression. However, the lack of efficient, appropriate imaging tools limits simultaneously tracking Zn2+ and H+ in living mouse brains. Thus, a well-designed dual-color fluorescent probe (DNP) was fabricated for the simultaneous monitoring of Zn2+ and H+ in the brains of mice with depression. Encountering Zn2+, the probe evoked bright blue fluorescence at 460 nm. Meanwhile, the red fluorescence at 680 nm was decreased with H+ addition. With blue/red dual fluorescence signal of DNP, we observed the synchronous increased Zn2+ and H+ in PC12 cells under oxidative stress. Notably, in vivo imaging for the first time revealed the simultaneous reduction of Zn2+ and pH in brains of mice with depression-like behaviors. Further results implied that the NMDA receptor might be responsible for the coinstantaneous fluctuation of Zn2+ and H+ during depression. Altogether, this work is conducive to the knowledge of neural signal transduction mechanisms, advancing our understanding of the pathogenesis in depression.
- Bai, Xiaoyi,Gong, Yulin,Li, Ping,Lu, Shuyi,Su, Di,Tang, Bo,Wang, Xin,Zhang, Wen,Zhang, Yandi
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- Unique pH-Sensitive RNA Binder for Ratiometric Visualization of Cell Apoptosis
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Fluorescent probes for monitoring cell apoptosis are powerful tools in biological and pathological research. However, ratiometric probes for in situ and real-time visualization of apoptosis with high accuracy are still deficient, which limits the studies relative to cell apoptosis. In this work, a pH-sensitive and positively charged RNA binder was designed and synthesized for the first time for the ratiometric visualization of cell apoptosis. In healthy cells, the probe targets mitochondria with basic matrixes and high membrane potential and displays intense emission in the blue and red channels. During apoptosis, the probe is released from mitochondria, binds to basophilic RNA, and shows emission in only the red channel. Consequently, cell apoptosis caused by drug treatment could be efficiently and clearly monitored in a ratiometric manner. The probe is expected to facilitate the study of cell apoptosis and relative areas.
- Tian, Minggang,Sun, Jie,Dong, Baoli,Lin, Weiying
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- Histidine-Rich Oligopeptides to Lessen Copper-Mediated Amyloid-β Toxicity
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Brain copper imbalance plays an important role in amyloid-β aggregation, tau hyperphosphorylation, and neurotoxicity observed in Alzheimer's disease (AD). Therefore, the administration of biocompatible metal-binding agents may offer a potential therapeutic solution to target mislocalized copper ions and restore metallostasis. Histidine-containing peptides and proteins are excellent metal binders and are found in many natural systems. The design of short peptides showing optimal binding properties represents a promising approach to capture and redistribute mislocalized metal ions, mainly due to their biocompatibility, ease of synthesis, and the possibility of fine-tuning their metal-binding affinities in order to suppress unwanted competitive binding with copper-containing proteins. In the present study, three peptides, namely HWH, HKCH, and HAH, have been designed with the objective of reducing copper toxicity in AD. These tripeptides form highly stable albumin-like complexes, showing higher affinity for CuII than that of Aβ(1-40). Furthermore, HWH, HKCH, and HAH act as very efficient inhibitors of copper-mediated reactive oxygen species (ROS) generation and prevent the copper-induced overproduction of toxic oligomers in the initial steps of amyloid aggregation in the presence of CuII ions. These tripeptides, and more generally small peptides including the sequence His-Xaa-His at the N-terminus, may therefore be considered as promising motifs for the future development of new and efficient anti-Alzheimer drugs.
- Caballero, Ana B.,Terol-Ordaz, Laia,Espargaró, Alba,Vázquez, Guillem,Nicolás, Ernesto,Sabaté, Raimon,Gamez, Patrick
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- Distinguishable multi-substance detection based on three-channel NIR fluorescent probe in physiology and pathology of living cells and zebrafish
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Mitochondria is the main organelle for the production of reactive sulfur species (RSS), such as homocysteine (Hcy), cysteine (Cys), glutathione (GSH) and sulfur dioxide (SO2). These compounds participate in a large number of physiological processes and play an extremely important role in maintaining the balance of life systems. Abnormal concentration and metabolism are closely related to many diseases. Due to their similarities in chemical properties, it is challenging to develop a single fluorescent probe to distinguish them simultaneously. Here, we synthesized the probe PI-CO[sbnd]NBD with three fluorophores, NBD-Cl and benzopyranate as the reaction sites of GSH/Cys/Hcy and SO2, respectively. Three biothiols all could cleavage ether bond to release benzopyrylium and coumarin moiety, which emitted red and blue fluorescence, but Cys/Hcy also could do intramolecular rearrangement after nucleophilic substitution, resulting in yellow fluorescence. Thus the probe can distinguish Cys/Hcy and GSH. Subsequently, only SO2 could quench red fluorescence by adding C[dbnd]C of benzopyrylium. The probe also could localize well in mitochondria by oxonium ion for all kinds of cells. The probe not only could detect above sulfur-containing active substances of intracellular and extracellular but also monitor the level of them under oxidative stress and apoptosis process in living cells and zebrafish.
- Li, Sha,Huo, Fangjun,Yue, Yongkang,Ma, Kaiqing,Wen, Ying,Yin, Caixia
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- A dual-site controlled ratiometric probe revealing the simultaneous down-regulation of pH in lysosomes and cytoplasm during autophagy
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In this work, a unique dual-site controlled fluorescent probe was presented for the sensitive and concurrent detection of pH in the cytoplasm and lysosomes. With the probe, the simultaneous down-regulation of pH in the lysosomes and cytoplasm during autophagy has been successfully revealed for the first time.
- Tian, Minggang,Liu, Chuang,Dong, Baoli,Zuo, Yujing,Lin, Weiying
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- Highly selective on-off fluorescence recognition of Fe3+ based on a coumarin derivative and its application in live-cell imaging
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A novel coumarin chemosensor, 7-hydroxy-2-oxo-N-(pyridin-2-ylmethyl)chromene-3-carboxamide (Probe 1), demonstrated significant selectivity towards Fe3+ ions. Probe 1 exhibited high fluorescence emission profile at 447?nm, excellent selectivity towards Fe3+ over other biologically important metal ions (Al3+, Ba2+, Co2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ and Sn2+). Interestingly, there was ~?30-fold decrease in fluorescence intensity upon Fe3+ binding. The limit of detection of Fe3+ was found to be 0.76?μM (~?40?ppb). Probe 1 also exhibited high potential as an intracellular chemosensor for Fe3+.
- Warrier, Sona,Kharkar, Prashant S.
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- Synthesis and Luminescent Properties of Eu3+ and Tb3+ Complexes with Coumarin-3-carboxylic Acids
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Abstract: New Eu3+ and Tb3+ complex compounds [Ln(H2O)2L2]Cl?H2O were synthesized on the basis of coumarin-3-carboxylic acid and its derivatives. Composition and structure of the ligands an
- Gromak,Kolokolov,Dotsenko,Aksenov,Aksenova
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p. 685 - 692
(2021/06/02)
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- 3-carboxylic acid and formyl-derived coumarins as photoinitiators in photo-oxidation or photo-reduction processes for photopolymerization upon visible light: Photocomposite synthesis and 3d printing applications
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In this paper, nine organic compounds based on the coumarin scaffold and different substituents were synthesized and used as high-performance photoinitiators for free radical pho-topolymerization (FRP) of meth(acrylate) functions under visible light irradiation using LED at 405 nm. In fact, these compounds showed a very high initiation capacity and very good polymerization profiles (both high rate of polymerization (Rp) and final conversion (FC)) using two and three-component photoinitiating systems based on coum/iodonium salt (0.1%/1% w/w) and coum/iodonium salt/amine (0.1%/1%/1% w/w/w), respectively. To demonstrate the efficiency of the initiation of photopolymerization, several techniques were used to study the photophysical and photochemical properties of coumarins, such as: UV-visible absorption spectroscopy, steady-state photolysis, real-time FTIR, and cyclic voltammetry. On the other hand, these compounds were also tested in direct laser write experiments (3D printing). The synthesis of photocomposites based on glass fiber or carbon fiber using an LED conveyor at 385 nm (0.7 W/cm2 ) was also examined.
- Dumur, Frédéric,Gigmes, Didier,Graff, Bernadette,Hamieh, Tayssir,Lalevée, Jacques,Noirbent, Guillaume,Rahal, Mahmoud,Toufaily, Joumana
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- Benzopyranic acid ester derivative as well as synthesis method and application thereof
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The invention provides a benzopyranic acid ester derivative as well as a synthesis method and application thereof; the Chinese name of the derivative is 7-(diethylamino)-2-(4-(4-(7-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)oxy)-2-oxy-2-H-chromene-3-carbonyl)piperazin-1-yl)phenyl)salt, and the derivative is named as PI-LS2. According to the invention, PI-LS2 is taken as a fluorescent probe, so that sulfide-containing compounds can be detected in a three-channel distinguishing manner. Specifically, based on the probe PI-LS2, sulfide is quantitatively distinguished and detected in a PBS buffer solution (pH=7.4, containing 20% of CH3CN, v/v) through an ultraviolet and visible spectrophotometer and a fluorescence spectrophotometer. The method can be used for carrying out special imaging on mitochondria of living cells and mercaptan and SO2 of zebra fish. In addition, the probe is successfully applied to monitoring oxidative stress and apoptosis processes of the living cells and the zebra fish.
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Paragraph 0036-0040
(2021/06/13)
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- NO Donor coumarin furoxan conjugates and pharmaceutical use thereof
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The invention belongs to the technical field of chemical pharmacy. Experiments prove that the furoxan conjugate has good water 3 - solubility, has excellent inhibitory activity on the growth of sensitive human tumor cells and resistant tumor cells, and NO
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- Method for synthesizing coumarin-3-carboxylic acid compounds by one-pot two-step method
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The invention relates to a method for synthesizing coumarin-3-carboxylic acid compounds by a one-pot two-step method. The structural formula of the coumarin-3-carboxylic acid compounds is shown in the description, wherein R1 is H , Cl , Br, NO2 , CH3 and HO . According to the synthesis process of the coumarin-3-carboxylic acid compounds, malonic acid, acetone and substituted salicylaldehyde serve as raw materials, iodine serves as a catalyst, acetic anhydride serves as a solvent, a series of coumarin-3-carboxylic acid compounds are synthesized through a one-pot cascade reaction, and the efficiency and the yield are greatly improved compared with a fractional step method.
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Paragraph 0053; 0056; 0058; 0077; 0079; 0084-0090
(2021/06/12)
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- Green synthesis method of coumarin-3-carboxylic acid compound
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The invention relates to a green synthesis method of a coumarin-3-carboxylic acid compound. The synthesis process of the coumarin-3-carboxylic acid compound is as follows: R1 is H, Cl, Br, NO2, CH3 and HO. A series of coumarin-3-carboxylic acid compounds are synthesized in one step without a catalyst by taking R1-substituted salicylaldehyde and Meldrum's acid as raw materials and water as a reaction medium, the process steps are simple, the method has universality, reaction liquid can be repeatedly added for reaction, no waste or waste liquid is generated, the yield of a target product is greater than 54.3%, and the method is an environment-friendly green synthesis method.
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Paragraph 0053-0061; 0077
(2021/06/26)
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- Coumarin derivative as well as synthesis method and application thereof
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The invention belongs to the field of medicinal chemistry, and discloses a coumarin derivative shown as a formula I, wherein R1 is selected from H, a C1-C4 alkyl group and a C1-C4 alkoxy group, R2 isselected from substituted or unsubstituted phenyl, and a
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Paragraph 0078-0080
(2021/03/24)
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- Fine-tuning thio-pyridazinediones as SMDC scaffolds (with intracellular thiol release via a novel self-immolative linker)
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Herein we report the synthesis of a library of thioalkyl- and thioaryl-pyridazinediones for thiol-based self-immolative release of cargo. A bisthioaryl-pyridazinedione is shown to be stable to serum protein albumin but unstable in intracellular conditions
- Fernández, Marcos,Shamsabadi, André,Chudasama, Vijay
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supporting information
p. 1125 - 1128
(2020/02/03)
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- Hydroxyl radical ratio type fluorescent probe as well as preparation method and application thereof
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The invention relates to a novel fluorescence resonance energy transfer (FRET) probe Rho-Bob, which is constructed by connecting rhodamine B (Rho) with an N2O type benzopyrrole boron complex (Bobpy),and is used for OH ratio type fluorescence detection and imaging. Rho-Bob shows the characteristic of being sensitive to the hydrophilicity/hydrophobicity of the environment, and has excellent mitochondrial localization capability. Rho-Bob is successfully applied to intracellular .OH ratio type fluorescence imaging. The .OH can be generated by a Fenton reaction, and can also be generated by activation of intracellular drugs. The Rho-Bob probe has high selectivity and sensitivity to hydroxyl radicals, and the detection limit is as low as a nanomole level (680nM). According to the invention, .OHgenerated by artemisinin molecules in cell mitochondria is observed for the first time by using Rho-Bob, and endogenous hydroxyl radicals are found to exist in zebra fish gastrointestinal tracts (GI)under normal culture conditions for the first time. The invention not only provides the practical probe for .OH detection and imaging, but also provides an important thought for constructing novel ratiometric probes of other ROS.
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Paragraph 0090-0093
(2020/05/08)
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- Site-specific fluorogenic protein labelling agent for bioconjugation
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Many clinically relevant therapeutic agents are formed from the conjugation of small molecules to biomolecules through conjugating linkers. In this study, two novel conjugating linkers were prepared, comprising a central coumarin core, functionalized with a dimaleimide moiety at one end and a terminal alkyne at the other. In our first design, we developed a protein labelling method that site-specifically introduces an alkyne functional group to a dicysteine target peptide tag that was genetically fused to a protein of interest. This method allows for the subsequent attachment of azide-functionalized cargo in the facile synthesis of novel protein-cargo conjugates. However, the fluorogenic aspect of the reaction between the linker and the target peptide was less than we desired. To address this shortcoming, a second linker reagent was prepared. This new design also allowed for the site-specific introduction of an alkyne functional group onto the target peptide, but in a highly fluorogenic and rapid manner. The site-specific addition of an alkyne group to a protein of interest was thus monitored in situ by fluorescence increase, prior to the attachment of azide-functionalized cargo. Finally, we also demonstrated that the cargo can also be attached first, in an azide/alkyne cycloaddition reaction, prior to fluorogenic conjugation with the target peptide-fused protein.
- Keillor, Jeffrey W.,Lee, Ann C.,Racine, Karl é.,Tsao, Kelvin K.
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- 7-Hydroxycoumarins Are Affinity-Based Fluorescent Probes for Competitive Binding Studies of Macrophage Migration Inhibitory Factor
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Macrophage migration inhibitory factor (MIF) is a cytokine with key roles in inflammation and cancer, which qualifies it as a potential drug target. Apart from its cytokine activity, MIF also harbors enzyme activity for keto-enol tautomerization. MIF enzymatic activity has been used for identification of MIF binding molecules that also interfere with its biological activity. However, MIF tautomerase activity assays are troubled by irregularities, thus creating a need for alternative methods. In this study, we identified a 7-hydroxycoumarin fluorophore with high affinity for the MIF tautomerase active site (Ki = 18 ± 1 nM) that binds with concomitant quenching of its fluorescence. This property enabled development of a novel competition-based assay format to quantify MIF binding. We also demonstrated that the 7-hydroxycoumarin fluorophore interfered with the MIF-CD74 interaction and inhibited proliferation of A549 cells. Thus, we provide a high-affinity MIF binder as a novel tool to advance MIF-oriented research.
- Xiao, Zhangping,Chen, Deng,Song, Shanshan,Van Der Vlag, Ramon,Van Der Wouden, Petra E.,Van Merkerk, Ronald,Cool, Robbert H.,Hirsch, Anna K. H.,Melgert, Barbro N.,Quax, Wim J.,Poelarends, Gerrit J.,Dekker, Frank J.
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p. 11920 - 11933
(2020/11/26)
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- Natural and semisynthetic oxyprenylated aromatic compounds as stimulators or inhibitors of melanogenesis
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It has been very recently shown how naturally occurring oxyprenylated coumarins are effective modulators of melanogenesis. In this short communication we wish to generalize the potentialities as skin tanning or whitening agents of a wider panel of natural and semisynthetic aromatic compounds, including coumarins, cinnamic and benzoic acids, cinnamaldehydes, benzaldehyde, and anthraquinone derivatives. A total number of 43 compounds have been tested assaying their capacity to inhibit or stimulate melanin biosynthesis in cultured murine Melan A cells. The wider number of chemicals herein under investigation allowed to depict a detailed structure-activity relationship, as the following: (a) benzoic acid derivatives are slightly pigmenting agent, for which the effect is more pronounced in compounds with longer O-side chains; (b) independently from the type of substitution, cinnamic acids are able to increase melanin biosynthesis, while benzaldehydes are able to decrease it; (c) coumarins with a 3,3-dimethylallyl or shorter skeletons as substituents in position 7 are tanning agents, while coumarins with farnesyloxy groups are whitening ones; (d) double oxyprenylation in position 6 and 7 and 3,3-dimethylallyl or geranyl skeletons have slight depigmenting capacities, while farnesyl skeletons tend to marginally increase the tanning effect; (e) the presence of electron withdrawing groups (acetyl, COOH, and -Cl) and geranyl or farnesyl oxyprenylated chains respectively in positions 3 and 7 of the coumarin nucleus lead to a whitening effect, and finally (f) oxyprenylated anthraquinones have only a weak depigmenting capacity.
- Genovese, Salvatore,Epifano, Francesco,Medina, Philippe de,Caron, Nicolas,Rives, Arnaud,Poirot, Marc,Poirot, Sandrine Silvent,Fiorito, Serena
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p. 181 - 190
(2019/03/23)
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- General Strategy for in Situ Generation of a Coumarin-Cu2+ Complex for Fluorescent Water Sensing
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The detection of moisture in organic solvents is very important before their use in water-sensitive reactions. Herein, we report that coumarins D1 and D2 were able to generate the corresponding water-sensitive copper complexes D1-Cu and D2-Cu in common organic solvents, which can be used as efficient fluorescent turn-on sensors for water. Single-crystal diffraction analysis of the reaction product indicated that the sensing mechanism is based on the formation of a water-bridged 3D supramolecular hydrogen-bonding network. We demonstrated that a hydroxyl or amine group substituted at the 7-position of the coumarin framework played a key role in the water-sensing performance of D1-Cu and D2-Cu, by acting as a hydrogen bond acceptor in the supramolecular network. This provided a general strategy for designing such coumarin-based copper complexes for fluorescent water sensing. The water-sensing behavior of D1-Cu and D2-Cu were determined to be fast, pH tolerant, and sensitive. As low as 0.0525 wt % of water in methanol can be detected using D1-Cu as the sensor. Moreover, D1-Cu was successfully used for moisture sensing in real commercial products.
- Cheng, Wenjing,Xie, Yiting,Yang, Zhiyu,Sun, Yueqing,Zhang, Ming-Zhi,Ding, Yubin,Zhang, Weihua
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p. 5817 - 5823
(2019/05/01)
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- Bi-locus high-sensitivity pH fluorescent probe and synthesis and application thereof
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The invention provides a bi-locus ratio type pH probe for high-sensitivity detection of changes of the pH value inside a cell. The synthesis steps of the probe are designed. The invention further provides application of the fluorescent probe in distinguishing live and dead cells. The probe synthesis method is simple and capable of achieving high-sensitivity ratio type detection of pH inside the cell, and has the great application prospect.
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Paragraph 0011; 0017
(2019/10/02)
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- An ultrasensitive ratiometric fluorescent probe based on the ICT-PET-FRET mechanism for the quantitative measurement of pH values in the endoplasmic reticulum (ER)
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Herein, we present a dual-site ratiometric fluorescent probe based on the ICT-PET-FRET mechanism for the detection of pH in the ER. The probe showed a highly sensitive response to pH in the range of 5.0-7.2, and could be applied for the quantitative measurement of the pH values in the ER during ER stress and dexamethanose-induced stimulation.
- Dong, Baoli,Song, Wenhui,Lu, Yaru,Kong, Xiuqi,Mehmood, Abdul Hadi,Lin, Weiying
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supporting information
p. 10776 - 10779
(2019/09/13)
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- Synthetic Fluorogenic Peptides Reveal Dynamic Substrate Specificity of Depalmitoylases
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Palmitoylation is a post-translational modification involving the thioesterification of cysteine residues with a 16-carbon-saturated fatty acid. Little is known about rates of depalmitoylation or the parameters that dictate these rates. Here we report a modular strategy to synthesize quenched fluorogenic substrates for the specific detection of depalmitoylase activity and for mapping the substrate specificity of individual depalmitoylases. We demonstrate that human depalmitoylases APT1 and APT2, and TgPPT1 from the parasite Toxoplasma gondii, have distinct specificities that depend on amino acid residues distal to the palmitoyl cysteine. This information informs the design of optimal and non-optimal substrates as well as isoform-selective substrates to detect the activity of a specific depalmitoylase in complex proteomes. In addition to providing tools for studying depalmitoylases, our findings identify a previously unrecognized mechanism for regulating steady-state levels of distinct palmitoylation sites by sequence-dependent control of depalmitoylation rates. Amara et al. describe a method for preparing positional scanning libraries of fluorogenic palmitoylated peptide substrates. This allowed identification of residues that are distal to the palmitoylation site that impact turnover. This information allowed the design of substrates that are selective for a specific depalmitoylating enzyme.
- Amara, Neri,Foe, Ian T.,Onguka, Ouma,Garland, Megan,Bogyo, Matthew
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p. 35 - 7,47
(2018/10/24)
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- Design, synthesis and biological evaluation of coumarin-3-carboxamides as selective carbonic anhydrase IX and XII inhibitors
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A series of novel 7-hydroxycoumarin-3-carboxamides was synthesized by the reaction of 7-hydroxy-2-oxo-2H-chromene-3-carboxylic acid with various substituted aromatic amines. The newly synthesized compounds were evaluated for their inhibitory activity against the four physiologically relevant human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms CA I, CA II, CA IX and CA XII. The CA inhibition results show that the newly synthesized 7-hydroxycoumarin-3-carboxamides (4a-n) exhibited selective inhibition of the tumor associated isoforms, CA IX and CA XII over CA I and II isoforms. The inhibition constants ranged from sub micromolar to low micromolar. Amongst all the compounds tested, compound 4m was the most effective inhibitor exhibiting sub micromolar potency against both hCA IX and hCA XII, with a Ki of 0.2 μM. Therefore, it can be anticipated that compound 4m can serve as a lead for development of anticancer therapy by exhibiting a novel mechanism of action. The binding modes of the most potent compounds within hCA IX and XII catalytic clefts were investigated by docking studies.
- Thacker, Pavitra S.,Alvala, Mallika,Arifuddin, Mohammed,Angeli, Andrea,Supuran, Claudiu T.
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p. 386 - 392
(2019/02/15)
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- Antifungal activity, mode of action variability, and subcellular distribution of coumarin-based antifungal azoles
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Azole antifungals inhibit the biosynthesis of ergosterol, the fungal equivalent of cholesterol in mammalian cells. Here we report an investigation of the activity of coumarin-substituted azole antifungals. Screening against a panel of Candida pathogens, including a mutant lacking CYP51, the target of antifungal azoles, revealed that this enzyme is inhibited by triazole-based antifungals, whereas imidazole-based derivatives have more than one mode of action. The imidazole-bearing antifungals more effectively reduced trailing growth associated with persistence and/or recurrence of fungal infections than triazole-based derivatives. The imidazole derivatives were more toxic to mammalian cells and more potently inhibited the activity of CYP3A4, which is one of the main causes of azole toxicity. Using live cell imaging, we showed that regardless of the type of azole ring fluorescent 7-diethylaminocoumarin-based azoles localized to the endoplasmic reticulum, the organelle that harbors CYP51. This study suggests that the coumarin is a promising scaffold for development of novel azole-based antifungals that effectively localize to the fungal cell endoplasmic reticulum.
- Elias, Rebecca,Benhamou, Raphael I.,Jaber, Qais Z.,Dorot, Orly,Zada, Sivan Louzoun,Oved,Pichinuk, Edward,Fridman
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p. 779 - 790
(2019/07/10)
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- Peptides N-connected to hydroxycoumarin and cinnamic acid derivatives: Synthesis and fluorescence spectroscopic, antioxidant and antimicrobial properties
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The tripeptide Tyr-Gly-Ser and a series of conjugations to coumarin, cinnamic and gallic acid were synthesized in salt form and their antioxidant and antimicrobial activities were investigated. The N-connecting hydroxycoumarin, cinnamic and gallic acid derivatives to peptides and the use of BBr3 as a demethylating agent for peptides was reported. Their activities were investigated based on the conjugated moiety structures. Studies of their activities showed that conjugated tripeptides 7,8-dihydroxycoumarin-peptide (17), caffeic acid-peptide (22) and gallic acid-peptide (28) were found to be superior to ascorbic acid with respect to their antioxidant activity, and 12, 14, 24, and 25 exhibited the most antimicrobial activity in the series compared to amoxicillin. Additionally, the incredible florescence intensity and brightness of 17 in water and DMSO, compared to other synthesized compounds, qualified this peptide as a suitable probe in the human body.
- Ghalehshahi, Hajar G.,Balalaie, Saeed,Aliahmadi, Atousa
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p. 8831 - 8842
(2018/06/11)
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- Low catalytic activity of the Cu(II)-binding motif (Xxx-Zzz-His; ATCUN) in reactive oxygen species production and inhibition by the Cu(i)-chelator BCS
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The catalytic redox activity of Cu(ii) bound to the motif NH2-Xxx-Zzz-His (ATCUN) with ascorbate and H2O2/O2 is very low and can be stopped via Cu(i)-chelation. This impacts its application as an artificial Cu-enzyme to degrade biomolecules via production of reactive oxygen species in a Cu(i)-chelator rich environment like the cytosol.
- Santoro, Alice,Walke, Gulshan,Vileno, Bertrand,Kulkarni, Prasad P.,Raibaut, Laurent,Faller, Peter
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supporting information
p. 11945 - 11948
(2018/11/27)
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- Design, synthesis and evaluation of novel multi-target-directed ligands for treatment of Alzheimer's disease based on coumarin and lipoic acid scaffolds
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A novel series of coumarin-lipoic acid conjugates were synthesized via cycloaddition click reaction to find out new multi-target-directed ligands (MTDLs) for treatment of Alzheimer's disease (AD). All of synthesized compounds were screened for neuroprotec
- Jalili-Baleh, Leili,Forootanfar, Hamid,Kü?ükk?l?n?, Tuba Tüylü,Nadri, Hamid,Abdolahi, Zahra,Ameri, Alieh,Jafari, Mandana,Ayazgok, Beyza,Baeeri, Maryam,Rahimifard, Mahban,Abbas Bukhari, Syed Nasir,Abdollahi, Mohammad,Ganjali, Mohammad Reza,Emami, Saeed,Khoobi, Mehdi,Foroumadi, Alireza
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p. 600 - 614
(2018/06/26)
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- Fluorogenic probes to monitor cytosolic phospholipase A2 activity
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Arachidonic acid derivatives equipped with either one or two fluorescent groups attached to the tip of the alkyl chains were synthesized and shown to function as inhibitor and substrate probes of cPLA2. The inhibitor probe was demonstrated to p
- Ng, Cheng Yang,Kwok, Timothy Xiong Wei,Tan, Francis Chee Kuan,Low, Chian-Ming,Lam, Yulin
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p. 1813 - 1816
(2017/02/10)
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- Coumarin derivative and preparation method thereof
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The invention relates to a coumarin derivative and a preparation method thereof. Specifically, the invention discloses novel 7-hydroxycoumarin-3-formyl-beta-alanyl aminoacyl-2-aminomethyl pyridine with anti-inflammatory activities, which is shown in a gen
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- A green chemical synthesis of coumarin-3-carboxylic and cinnamic acids using crop-derived products and waste waters as solvents
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Crop-derived products, like juices obtained from edible fruits and vegetables, and waste waters deriving from agricultural and industrial processing have been recently exploited to efficiently promote several ‘classic’ and innovative synthetic organic reactions. Such a green chemical approach prevented the use of toxic, polluting, and hazardous materials and in the mean time allowed to increase the commercial values of crop products and industrial byproducts. Coumarin-3-carboxylic and cinnamic acids represent classes of naturally occurring and semi-synthetic compounds with interesting and promising pharmacological activities. In this Letter a new and improved methodology for the Knoevenagel condensation yielding the title compounds using juices from edible fruits and vegetables (lemon, grapefruit, carrot, pomegranate, kiwi, vinegar, tomato), liqueurs (limoncello), and waste waters (buttermilk and residues of olive processing) as solvents is described. Coumarin-3-carboxylic and cinnamic acids have been synthesized in excellent yields by ultrasound irradiation from differently substituted 2-hydroxybenzaldehydes, 2-hydroxyacetophenones, and benzaldehydes, and Meldrum's acid as starting substrates. The findings described herein enforce the concept of the usefulness of products and byproducts derived from agriculture and food industry to accomplish green chemical processes.
- Fiorito, Serena,Taddeo, Vito Alessandro,Genovese, Salvatore,Epifano, Francesco
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supporting information
p. 4795 - 4798
(2016/10/05)
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- Et3N catalyzed cascade reaction of Meldrum’s acid with ortho-hydroxyaryl aldehydes for the synthesis of coumarin-3-carboxylic acids under solvent-less condition
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Abstract: The synthesis of coumarin-3-carboxylic acids in good yields is realized through a triethylamine catalyzed Knoevenagel-intramolecular cyclization tandem reaction of Meldrum’s acid with various ortho-hydroxyaryl aldehydes. This method expands the catalyst library about the synthesis of coumarin-3-carboxylic acids and also has advantages of using much less water as solvent, a cheap and eco-friendly catalyst, clean reaction conditions, simple workup procedure and easy isolation. Graphical Abstract: [Figure not available: see fulltext.]
- Pan, Wan-Yü,Xiao, Yü-Meng,Xiong, Hou-Qing,Lü, Cheng-Wei
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p. 7057 - 7063
(2016/08/25)
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- Gastroprotective activity of synthetic coumarins: Role of endogenous prostaglandins, nitric oxide, non-protein sulfhydryls and vanilloid receptors
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Natural or synthetic coumarins showed gastroprotective and antiulcer activity in animal models. In this study, we have synthetized twenty coumarins using classic methods to evaluate their gastroprotective effects on the ethanol/HCl-induced gastric lesion model in mice at 20?mg/kg. Among the coumarins synthetized, compounds 6 and 10 showed the greatest gastroprotective activity being as active as lansoprazole at 20?mg/kg and reducing gastric lesions by 75 and 76%, respectively. Then, in a second experiment, compounds 6 and 10 were re-evaluated in order to understand the possible mode of gastroprotective activity. Regarding coumarin 6, the protective effect was reduced by pre-treatment of the mice with N-ethylmaleimide and l-NAME suggesting that sulfhydryl compounds and endogenous nitric oxide are involved in its gastroprotective activity. While for coumarin 10 the effect was reduced by pre-treatment with indomethacin suggesting that prostaglandins are positively involved in its gastroprotective activity.
- Sepulveda, Beatriz,Quispe, Cristina,Simirgiotis, Mario,Torres-Benítez, Alfredo,Reyes-Ortíz, Johanna,Areche, Carlos,García-Beltrán, Olimpo
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supporting information
p. 5732 - 5735
(2016/11/25)
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- Is ascorbate Dr Jekyll or Mr Hyde in the Cu(Aβ) mediated oxidative stress linked to Alzheimer's disease?
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Evaluation of the pro versus antioxidant activity of ascorbate regarding Cu(Aβ) induced reactive oxygen species production in the context of Alzheimer's disease shows that a protective activity can only be observed at high ascorbate concentration for exogenous molecules but not for the amyloid-β peptide itself.
- Cheignon, Clémence,Collin, Fabrice,Faller, Peter,Hureau, Christelle
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supporting information
p. 12627 - 12631
(2016/08/24)
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- Synthesis and anticholinesterase activity of coumarin-3-carboxamides bearing tryptamine moiety
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A number of N-(2-(1H-indol-3-yl)ethyl)-2-oxo-2H-chromene-3-carboxamides were synthesized and tested against AChE and BuChE. The in?vitro assessment of the synthesized compounds 4a-o revealed that most of them had significant activity toward AChE. The SAR study demonstrated that the introduction of benzyloxy moiety on the 7-position of coumarin scaffold can improve the anti-AChE activity. The best result was obtained with 7-(4-fluorobenzyl)oxy moiety in the case of compound 4o, displaying IC50value of 0.16?μM. Based on the docking study of AChE, the prototype compound 4o was laid across the active site and occupied both peripheral anionic site (PAS) and catalytic anionic site (CAS).
- Ghanei-Nasab, Samaneh,Khoobi, Mehdi,Hadizadeh, Farzin,Marjani, Azam,Moradi, Alireza,Nadri, Hamid,Emami, Saeed,Foroumadi, Alireza,Shafiee, Abbas
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- Discovery of quinazoline-based fluorescent probes to α1-adrenergic receptors
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α1-Adrenergic receptors (α1-ARs), as the essential members of G protein-coupled receptors (GPCRs), can mediate numerous physiological responses in the sympathetic nervous system. In the current research, a series of quinazoline-based small-molecule fluorescent probes to α1-ARs (1a-1e), including two parts, a pharmacophore for α1-AR recognition and a fluorophore for visualization, were well designed and synthesized. The biological evaluation results displayed that these probes held reasonable fluorescent properties, high affinity, accepted cell toxicity, and excellent subcellular localization imaging potential for α1-ARs.
- Zhang, Wei,Ma, Zhao,Li, Wenhua,Li, Geng,Chen, Laizhong,Liu, Zhenzhen,Du, Lupei,Li, Minyong
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p. 502 - 506
(2015/05/27)
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- Design and synthesis of coumarin-3-acylamino derivatives to scavenge radicals and to protect DNA
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In this study, a series of coumarin-3-acylamino derivatives containing phenethylamine moiety or tyramine moiety were synthesized and their antioxidant activities were evaluated by Cu2+/glutathione(GSH)-, OH- and 2,2′-azobis(2-amidinopropane hyd
- Yang, Yang,Liu, Qing-Wen,Shi, Ye,Song, Zhi-Guang,Jin, Ying-Hua,Liu, Zai-Qun
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- New multi-target-directed small molecules against Alzheimer's disease: A combination of resveratrol and clioquinol
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Alzheimer's disease (AD) is currently one of the most difficult and challenging diseases to treat. Based on the 'multi-target-directed ligands' (MTDLs) strategy, we designed and synthesised a series of new compounds against AD by combining the pharmacophores of resveratrol and clioquinol. The results of biological activity tests showed that the hybrids exhibited excellent MTDL properties: a significant ability to inhibit self-induced β-amyloid (Aβ) aggregation and copper(ii)-induced Aβ aggregation, potential antioxidant behaviour (ORAC-FL value of 0.9-3.2 Trolox equivalents) and biometal chelation. Among these compounds, (E)-5-(4-hydroxystyryl)quinoline-8-ol (10c) showed the most potent ability to inhibit self-induced Aβ aggregation (IC50 = 8.50 μM) and copper(ii)-induced Aβ aggregation and to disassemble the well-structured Aβ fibrils generated by self- and copper(ii)-induced Aβ aggregation. Note that 10c could also control Cu(i/ii)-triggered hydroxyl radical (OH) production by halting copper redox cycling via metal complexation, as confirmed by a Cu-ascorbate redox system assay. Importantly, 10c did not show acute toxicity in mice at doses of up to 2000 mg kg-1 and was able to cross the blood-brain barrier (BBB), according to a parallel artificial membrane permeation assay. These results indicate that compound 10c is a promising multifunctional compound for the development of novel drugs for AD. This journal is the Partner Organisations 2014.
- Mao, Fei,Yan, Jun,Li, Jianheng,Jia, Xian,Miao, Hui,Sun, Yang,Huang, Ling,Li, Xingshu
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supporting information
p. 5936 - 5944
(2014/08/05)
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- COATINGS FOR MEASURING PH CHANGES
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A pH detectable coating. The pH detectable coating includes a pH insensitive fluorescent dye and a pH sensitive fluorescent dye. The pH insensitive fluorescent dye and the pH sensitive fluorescent dye are attached to a surface. The ratio of the fluorescent intensity of the pH insensitive fluorescent dye to the fluorescent intensity of the pH sensitive fluorescent dye varies according to the pH of an environment into which the surface is placed.
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- Synthesis of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones and coumarin-3-carboxylic acids via reaction of nitrones and Meldrum's acid
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A variety of nitrones have been synthesized and reacted with Meldrum's acid without the aid of any catalysts. Selectively, 5- arylidene-2,2-dimethyl-1,3- dioxane-4,6-diones have been obtained with excellent yields under environmentally benign reaction conditions. Whereas, nitrone of salisylaldehydes with Meldrum's acid afford cyclized products i.e. coumarin-3- carboxylic acids.
- Kumar, Dhruva,Suresh,Sandhu, Jagir S.
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p. 1157 - 1160
(2013/09/24)
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- CHEMICAL ENHANCEMENT BY NANOMATERIALS UNDER X-RAY IRRADIATION
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A method for dynamic enhancement of chemical reactions by nanomaterials under hard X-ray irradiation. The nanomaterials were gold and platinum nanoparticles, and the chemical reaction employed was the hydroxylation of coumarin carboxylic acid. The reaction yield was enhanced 2000 times over that predicted on the basis of the absorption of X-rays only by the nanoparticles, and the enhancement was found for the first time to depend on the X-ray dose rate. The maximum turnover frequency was measured at 1 16 x 10-4 s-1 Gy-1. We call this process chemical enhancement, which is defined as the increased yield of a chemical reaction due to the chemical properties of the added materials. The chemical enhancement described here is believed to be ubiquitous and may significantly alter the outcome of chemical reactions under X-ray irradiation with the assistance of nanomaterials.
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Paragraph 0008; 0050-0066
(2013/07/25)
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- Novel coumarin-3-carboxamides bearing N-benzylpiperidine moiety as potent acetylcholinesterase inhibitors
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Abstract Some novel coumarin-3-carboxamide derivatives linked to N-benzylpiperidine scaffold were synthesized and evaluated as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors. The screening results showed that most of compounds exhibited potent anti-AChE activity in the range of nM concentrations. Among them, compound 10c bearing an N-ethylcarboxamide linker and a 6-nitro substituent showed the most potent activity (IC50 = 0.3 nM) and the highest selectivity (SI = 26,300). Compound 10c was 46-fold more potent than standard drug donepezil against AChE. The kinetic study revealed that compound 10c exhibited mixed-type inhibition against AChE. Protein-ligand docking study demonstrated that the target compounds have dual binding site interaction mode and these results are in agreement with kinetic study.
- Asadipour, Ali,Alipour, Masoumeh,Jafari, Mona,Khoobi, Mehdi,Emami, Saeed,Nadri, Hamid,Sakhteman, Amirhossein,Moradi, Alireza,Sheibani, Vahid,Homayouni Moghadam, Farshad,Shafiee, Abbas,Foroumadi, Alireza
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p. 623 - 630
(2013/12/04)
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- Rapid synthesis of novel and known coumarin-3-carboxylic acids using stannous chloride dihydrate under solvent-free conditions
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Various coumarin-3-carboxylic acid (=2-oxo-2H-1-benzopyran-3-carboxylic acid; CcaH) derivatives have been synthesized in good yields using catalytic amounts of SnCl2·2 H2O under solvent-free conditions. This inexpensive, nontoxic, and readily available catalytic system (10 mol-%) efficiently catalyzes the Knoevenagel condensation and intramolecular cyclization of various 2-hydroxybenzaldehydes or acetophenones with Meldrum's acid. High product yields, use of inexpensive and safe catalyst, and solvent-free conditions display both economic and environmental advantages. Copyright
- Karami, Bahador,Farahi, Mahnaz,Khodabakhshi, Saeed
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experimental part
p. 455 - 460
(2012/05/04)
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- Site-specific protein propargylation using tissue transglutaminase
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Transglutaminases (TGases) catalyse the transamidation of glutamine residues with primary amines. Herein we report the first FRET-based activity assay for the direct detection of the ligation (transamidation) reaction mediated by tissue TGase (TG2). This novel assay was then used in a microtiter plate-based screen of a library of 18 potential amine substrates. From this screen it was discovered that propargyl amine serves as an excellent substrate for TG2. Subsequently, propargyl amine and 2-azidoethyl amine were validated independently as TG2 substrates with KM values of 44 ± 4 μM, and 0.99 ± 0.06 mM, respectively. In a proof-of-principle protein labelling experiment, the protein casein was selectively functionalized with propargyl amine using TG2 and subsequently fluorescently labelled through a dipolar cycloaddition reaction with an azido-fluorescein conjugate. This application demonstrates the strong potential of using TG2 for site-specific protein modification through a combination of enzymatic and bioorthogonal chemistry. The Royal Society of Chemistry 2012.
- Gnaccarini, Claudio,Ben-Tahar, Wajih,Mulani, Amina,Roy, Isabelle,Lubell, William D.,Pelletier, Joelle N.,Keillor, Jeffrey W.
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experimental part
p. 5258 - 5265
(2012/07/28)
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- Biological evaluation of coumarin derivatives as mushroom tyrosinase inhibitors
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A series of coumarin derivatives were synthesised and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that some of the synthesised compounds exhibited significant inhibitory activities. Especially, 2-(1-(coumarin-3-yl)ethylidene) hydrazinecarbothioamide bearing thiose-micarbazide group exhibited the most potent tyrosinase inhibitory activity with IC50 value of 3.44 μM. The inhibition mechanism analysis of 2-(1-(coumarin-3-yl)-ethylidene) hydrazinecarbothioamide and 2-(1-(6-chlorocoumarin-3-yl)ethylidene)- hydrazinecarbothioamide demonstrated that the inhibitory effects of the compounds on the tyrosinase were irreversible. Preliminary structure activity relationships' (SARs) analysis suggested that further development of such compounds might be of interest.
- Liu, Jinbing,Wu, Fengyan,Chen, Lingjuan,Zhao, Liangzhong,Zhao, Zibing,Wang, Min,Lei, Sulan
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p. 2872 - 2878
(2012/10/30)
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- Triton-B adsorbed on flysh: An efficient support for the base catalysed reactions under microwave irradiations
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The application of Triton-B adsorbed on flyash (a waste material of thermal plants ) has been reported for the variety of base catalysed reactions such as synthesis of cinnamic acids by Deobner reaction, synthesis of 1-(2-hydroxyphenyl)-5-phenylpent-4-ene-1, 3-diones by Baker-Venkataraman reaction and synthesis of 3-carboxycoumarins by knoevenagel reaction. This material also acts as a support for the reaction and avoids the use of any solvent in the reaction maintaining the norms of Green Chemistry.
- Goel, Vijender
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p. 1725 - 1728
(2013/06/27)
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- Synthesis and evaluation of self-calibrating ratiometric viscosity sensors
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We describe the design, synthesis and fluorescent profile of a family of self-calibrating dyes that provide ratiometric measurements of fluid viscosity. The design is based on covalently linking a primary fluorophore (reference) that displays a viscosity-independent fluorescence emission with a secondary fluorophore (sensor) that exhibits a viscosity-sensitive fluorescence emission. Characterization of fluorescent properties was made with separate excitation of the units and through Resonance Energy Transfer from the reference to the sensor dye. The chemical structures of both fluorophores and the linker length have been evaluated in order to optimize the overall brightness and sensitivity of the viscosity measurements. We also present an application of such ratiometric dyes for the detection of membrane viscosity changes in a liposome model.
- Yoon, Hyung-Jo,Dakanali, Marianna,Lichlyter, Darcy,Chang, Willy M.,Nguyen, Karen A.,Nipper, Matthew E.,Haidekker, Mark A.,Theodorakis, Emmanuel A.
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p. 3530 - 3540
(2011/06/25)
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