Synthèse et caractérisation photophysique et électrochimique d'une nouvelle classe de composés à base de fluorène et 2-thiophène

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Développement de nouveaux matériaux conjugués aux propriétés opto-électroniques modulables : de l’électrochromisme à la fluorescence.

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Synthesis and identification of a new class of (S)-2,6-diamino-4,5,6,7-tetrahydrobenzo[d]thiazole derivatives as potent antileukemic agents

Benzothiazoles are multitarget agents with broad spectrum of biological activity. Among the antitumor agents discovered in recent years, the identification of various 2-(4-aminophenyl) benzothiazoles as potent and selective antitumor drugs against different cancer cell lines has stimulated remarkable interest. Some of the benzothiazoles are known to induce cell cycle arrest, activation of caspases and interaction with DNA molecule. Based on these interesting properties of benzothiazoles and to obtain new biologically active agents, a series of novel 4,5,6,7-tetrahydrobenzo[d]thiazole derivatives 5(a-i) were synthesized and evaluated for their efficacy as antileukemic agents in human leukemia cells (K562 and Reh). The chemical structures of the synthesized compounds were confirmed by H-1 NMR, LCMS and IR analysis. The cytotoxicity of these compounds were determined using trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Results showed that, these compounds mediate a significant cytotoxic response to cancer cell lines tested. We found that the compounds having electron withdrawing groups at different positions of the phenyl ring of the thiourea moiety displayed significant cytotoxic effect with IC50 value less than 60 mu M. To rationalize the role of electron withdrawing group in the induction of cytotoxicity, we have chosen molecule 5g (IC50 similar to 15 mu M) which is having chloro substitution at ortho and para positions. Flow cytometric analysis of annexin V-FITC/ propidium iodide (PI) double staining and DNA fragmentation suggest that 5g can induce apoptosis.

Central nervous system drugs: Low temperature X-ray structures of (I) the base 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine (4030W92) and (II) 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine methanesulphonic acid salt (227C89)

The X-ray crystal structures of (I), the base 4030W92, 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine, C11H9Cl2FN4, and (II) 227C89, the methanesulphonic acid salt of 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine, C11H11Cl2N4 center dot CH3O3S, have been carried out at low temperature. A detailed comparison of the two structures is given. Structure (I) is non-centrosymmetric, crystallizing in space group P2(1) with unit cell a = 10.821(3), b = 8.290(3), c = 13.819(4) angstrom, beta = 105.980(6)degrees, V = 1191.8(6) angstrom(3), Z = 4 (two molecules per asymmetric unit) and density (calculated) = 1.600 mg/m(3). Structure (II) crystallizes in the triclinic space group P (1) over bar with unit cell a = 7.686(2), b = 8.233(2), c = 12.234(2) angstrom, alpha = 78.379(4), beta = 87.195(4), gamma = 86.811(4)degrees, V = 756.6(2) angstrom(3), Z = 2, density (calculated) = 1.603 mg/m(3). Final R indices [I > 2sigma(I)] are R1 = 0.0572, wR2 = 0.1003 for (I) and R1 = 0.0558, wR2 = 0.0982 for (II). R indices (all data) are R1 = 0.0983, wR2 = 0.1116 for (I) and R1 = 0.1009, wR2 = 0.1117 for (II). 5- Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this structural series and their biological activities.

X-ray crystallographic structures of two lamotrigine analogues: (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine water solvate and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine methanol solvate

The X-ray crystal structures of two lamotrigine derivatives (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine, C9H8ClN5, (465BL) as a hydrate, and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine, C9H7Cl2N5, (469BR) as a methanol solvate, have been carried out at liquid nitrogen temperature and room temperature, respectively. A detailed comparison of the two structures is given. Both are centrosymmetric with (I) in the orthorhombic space group Pbca, a = 12.2507(3), b = 15.7160(6), c = 21.71496(9) angstrom, Z = 16, and (II) in the monoclinic space group C2/c, a = 38.553(3), b = 4.9586(2), c = 14.546(2) angstrom, beta = 111.59(1)degrees, Z = 8. Final R indices [I > 2sigma(I)] for (I) are R1 = 0.0670, wR2 = 0.1515 and for (II) R1 = 0.0434, wR2 = 0.1185. Structure (I) has water of crystallization in the lattice and (II) includes a solvated CH3OH. Structure (I) is characterized by having two crystallographically independent molecules, A and B, of 465BL, per asymmetric unit. Molecule B has a very unusual feature in that the 2-chlorophenyl ring is statistically disordered, occupying site (1) in 87.5% of the structure and site (2) in 12.5% of the structure. Sites (1) and (2) are related by an exact 180 degrees pivot of the phenyl ring about the ring linkage bond. The presence of two independent molecules per asymmetric unit provides an ideal opportunity for the conformational flexibility of the molecule 465BL to be studied. Structure (I) also includes a further unusual feature in that the lattice contains one fully occupied water molecule and an additional solvated water which is only 33% occupied.

Low temperature X-ray crystallographic structures of two lamotrigine analogues: (I) 2-methyl,3-amino, 5-imino-6-(2,3-dichlorophenyl)-1,2,4-triazine water solvate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine isethionate, hemi-hydrate

The X-ray crystal structures of two lamotrigine derivatives (I) 2-methyl, 3-amino, 5-imino-6-(2, 3-dichlorophenyl)-1,2,4-triazine, C10H9Cl2N5, as the hemi hydrate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine, C10H10Cl2N5, as the isethionate-water solvate, have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are monoclinic and centrosymmetric, with (I) in space group C2/c, and (II) in space group P2(1)/n. For (I) the unit cell dimensions are a = 19.5466(10), b = 7.5483(4), c = 15.7861(8) angstrom, beta = 91.458(3)degrees, volume = 2328.4(2) angstrom(3), Z = 8, density = 1.590 Mg/m(3); for (II). For (II) the unit cell dimensions are a = 6.0566(2), b = 11.0084(4) c = 23.9973(9) angstrom, beta = 92.587(3)degrees, volume = 1598.35(10) angstrom(3), Z = 4, density = 1.597 Mg/m(3). For (I) final R indices [I > 2sigma(I)] are R1 = 0.0356, wR2 = 0.0782 and R indices (all data) are R1 = 0.0424, wR2 = 0.0817. For (II) final R indices [I > 2sigma(I)] are R1 = 0.0380, wR2 = 0.0871 and R indices (all data) R1 = 0.0558, wR2 = 0.0949. Both structures have a molecule of water of crystallization and (II) also includes a solvated CH3SO3. Comparisons are made between the two structures. Structure (I) is very unusual in having a = NH group at position C5' on the triazine ring. No other examples of this particular substitution, which is usually -NH2, have been reported.

1,4-Diamino-2-butanone, a wide-spectrum microbicide, yields reactive species by metal-catalyzed oxidation

The alpha-aminoketone 1,4-diamino-2-butanone (DAB), a putrescine analogue, is highly toxic to various microorganisms, including Trypanosoma cruzi. However, little is known about the molecular mechanisms underlying DAB`s cytotoxic properties. We report here that DAB (pK(a) 7.5 and 9.5) undergoes aerobic oxidation in phosphate buffer, pH 7.4, at 37 degrees C, catalyzed by Fe(II) and Cu(II) ions yielding NH(4)(+) ion, H(2)O(2), and 4-amino-2-oxobutanal (oxoDAB). OxoDAB, like methylglyoxal and other alpha-oxoaldehydes, is expected to cause protein aggregation and nucleobase lesions. Propagation of DAB oxidation by superoxide radical was confirmed by the inhibitory effect of added SOD (50 U ml(-1)) and stimulatory effect of xanthine/xanthine oxidase, a source of superoxide radical. EPR spin trapping studies with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) revealed an adduct attributable to DMPO-HO(center dot), and those with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone or 3,5-dibromo-4-nitrosobenzenesulfonic acid, a six-line adduct assignable to a DAB(center dot) resonant enoyl radical adduct. Added horse spleen ferritin (HoSF) and bovine apo-transferrin underwent oxidative changes in tryptophan residues in the presence of 1.0-10 mM DAB. Iron release from HoSF was observed as well. Assays performed with fluorescein-encapsulated liposomes of cardiolipin and phosphatidylcholine (20:80) incubated with DAB resulted in extensive lipid peroxidation and consequent vesicle permeabilization. DAB (0-10 mM) administration to cultured LLC-MK2 epithelial cells caused a decline in cell viability, which was inhibited by preaddition of either catalase (4.5 mu M) or aminoguanidine (25 mM). Our findings support the hypothesis that DAB toxicity to several pathogenic microorganisms previously described may involve not only reported inhibition of polyamine metabolism but also DAB pro-oxidant activity. (C) 2011 Elsevier Inc. All rights reserved.

1,4-Diamino-2-butanone, a putrescine analogue, promotes redox imbalance in Trypanosoma cruzi and mammalian cells

The putrescine analogue 1,4-diamino-2-butanone (DAB) is highly toxic to various microorganisms, including Trypanosoma cruzi. Similar to other a-aminocarbonyl metabolites. DAB exhibits pro-oxidant properties. DAB undergoes metal-catalyzed oxidation yielding H2O2, NH4+ ion, and a highly toxic alpha-oxoaldehyde. In vitro. DAB decreases mammalian cell viability associated with changes in redox balance. Here, we aim to clarify the DAB pro-oxidant effects on trypomastigotes and on intracellular T. cruzi amastigotes. DAB (0.05-5 mM) exposure in trypomastigotes, the infective stage of T. cruzi, leads to a decline in parasite viability (IC50 c.a. 0.2 mM DAB; 4 h incubation), changes in morphology, thiol redox imbalance, and increased TcSOD activity. Medium supplementation with catalase (2.5 mu M) protects trypomastigotes against DAB toxicity, while host cell invasion by trypomastigotes is hampered by DAB. Additionally, intracellular amastigotes are susceptible to DAB toxicity. Furthermore, pre-treatment with 100-500 mu M buthionine sulfoximine (BSO) of LLC-MK2 potentiates DAB cytotoxicity, whereas 5 mM N-acetyl-cysteine (NAC) protects cells from oxidative stress. Together, these data support the hypothesis that redox imbalance contributes to DAB cytotoxicity in both T. cruzi and mammalian host cells. (C) 2012 Elsevier Inc. All rights reserved.

Selektiv deblockierbare 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffolds für die kombinatorische Synthese potentieller RNA-Liganden

Aminoglydosid-Antibiotika wie Neomycin B oder Cyclopeptid-Antibiotike wie Viaomycin sind dafür bekannt, daß sie selektiv an RNA binden können. Diese Interaktionen beruhen sowohl auf elektrostatischen Wechselwirkungen als auch auf H-Brücken-Bindungen. Des weiteren ist die definierte räumliche Anordnung von Donor- und Akzeptor-Resten in den Strukturen der RNA-Liganden wichtig für die Affinität. Eine Möglichkeit natürliche RNA-Liganden zu imitieren ist der Einsatz polyfunktioneller Template wie zum Beispiel das 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffold. Mit Hilfe dieser Scaffolds können dann verschiedene positv geladene Reste und Donatoren sowie Akzeptoren für H-Brücken-Bindungen oder auch Interkalatoren räumlich definiert präsentiert werden. Für die unabhängige Funktionalisierung einer jeden Position ist ein Satz orthogonal stabiler Schutzgruppen nötig, wobei eine Hydroxylguppe durch einen Anker ersetzt wird, der eine Anbindung des Scaffolds an einen polymeren Träger ermöglicht. Das neu entwickelte 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffold ist das erste Monosaccharid-Templat, das in allen fünf Positionen mit orthogonal stabilen Schutzgruppen blockiert ist. Alle Positionen könne in beliebiger Reihenfolge selektiv deblockiert und anschließend derivatisiert werden. Das Scaffold kann mit Aminosäuren, Guanidinen oder Interkalatoren umgesetzt werden, um so natürlich vorkommende RNA-bindende Aminoglycoside oder Peptide zu imitieren. Aufbauend auf diesem Monosaccharid-Templat wurde eine Bibliothek von über 100 potentiellen RNA-Liganden synthetisiert, die im Rahmen des Sonderforschungsbereichs 579 (RNA-Liganden-Wechselwirkungen) in Zellassays auf ihre Fähigkeit zur Hemmung der Tat/TAR-Wechselwirkung untersucht wurden, wobei bis jetzt 9 Verbindungen mit einer hemmenden Wirkung im micromolaren Bereich gefunden wurden.

Selektiv deblockierbare Diamino-D-Galactose-Scaffolds für die kombinatorische Synthese potentieller RNA-Liganden

Die Aufklärung der Schlüsselrolle der RNA in zahlreichen biologischen Prozessen, die sich aus ihren selektiven Wechselwirkungen mit anderen RNA-Molekülen, Proteinen, Peptiden bzw. Antibiotika ergibt, ist für die Wirkstoffforschung von großer Bedeutung. Die Aminoglycoside und Antibiotika, die durch eine Hemmung der Proteinbiosynthese schon seit längerem bekannt sind, dienen als Leitstrukuren für die Synthese von weiteren Wirkstoffen. Die meisten Aminoglycosid-Antibiotika beinhalten Aminozucker, die mit dem rn2-Desoxystreptamin-Gerüst verbunden sind. Die stereochemische Vielfalt der Substitutionsstellen für Amino- und Hydroxylgruppen in diesem Gerüst und deren beschränkte konformative Flexibilität bieten vielseitige Möglichkeiten, um potenzielle RNA-Liganden so zu gestalten, dass es zu einer spezifischen Erkennung von RNA-Strukturen kommen kann. Ein wichtiger Vertreter dieser Antibiotika, Neomycin B, von dessen Struktur die Entwicklung des Diaminogalactose-Templates abgeleitet wurde, wurde in dieser Arbeit als Leitstruktur gewählt. Die Synthese von Diaminogalactose-Scaffolds wurde zunächst in Lösung durchgeführt. Anschließend wurden die Bausteine 2 und 4 an einen polymeren Träger gebunden.rnNach Prüfung der orthogonalen Stabilität der Schutzgruppen wurde mit den Scaffolds 2 und 4 eine Bibliothek von 65 Verbindungen hergestellt. Mit 42 dieser Verbindungen wurden anschließend Zellassays im Rahmen des Sonderforschungsbereichs 579 (RNA-Liganden-Wechselwirkungen) durchgeführt, um ihre Cytotoxizität zu prüfen. Für einzelne Verbindungen konnten die optimalen Konzentrationen bestimmt werden, bei denen zukünftige Tests für die Tat/TAR Wechselwirkung ohne störende cytotoxische Effekte durchgeführt werden können.rn

Cloning and expression in Escherichia coli of the OGG1 gene of Saccharomyces cerevisiae, which codes for a DNA glycosylase that excises 7,8-dihydro-8-oxoguanine and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine.

A spontaneous mutator strain of Escherichia coli (fpg mutY) was used to clone the OGG1 gene of Saccharomyces cerevisiae, which encodes a DNA glycosylase activity that excises 7,8-dihydro-8-oxoguanine (8-OxoG). E. coli (fpg mutY) was transformed by a yeast DNA library, and clones that showed a reduced spontaneous mutagenesis were selected. The antimutator activity was associated with pYSB10, an 11-kbp recombinant plasmid. Cell-free extracts of E. coli (fpg mutY) harboring pYSB10 possess an enzymatic activity that cleaves a 34-mer oligonucleotide containing a single 8-oxoG opposite a cytosine (8-OxoG/C). The yeast DNA fragment of 1.7 kbp that suppresses spontaneous mutagenesis and overproduces the 8-OxoG/C cleavage activity was sequenced and mapped to chromosome XIII. DNA sequencing identified an open reading frame, designated OGG1, which encodes a protein of 376 amino acids with a molecular mass of 43 kDa. The OGG1 gene was inserted in plasmid pUC19, yielding pYSB110. E. coli (fpg) harboring pYSB110 was used to purify the Ogg1 protein of S. cerevisiae to apparent homogeneity. The Ogg1 protein possesses a DNA glycosylase activity that releases 8-OxoG and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine. The Ogg1 protein preferentially incises DNA that contains 8-OxoG opposite cytosine (8-OxoG/C) or thymine (8-OxoG/T). In contrast, Ogg1 protein does not incise the duplex where an adenine is placed opposite 8-OxoG (8-OxoG/A). The mechanism of strand cleavage by Ogg1 protein is probably due to the excision of 8-OxoG followed by a beta-elimination at the resulting apurinic/apyrimidinic site.

Mecanismos e a influência de ferro lábil em processos nitrosativos intracelulares utilizando o indicador fluorescente 4,5 diamino fluoresceína

Neste trabalho foram investigados os mecanismos e o perfil cinético de processos nitrosativos do ponto de vista da nitrosação do indicador 4,5-diamino fluoresceina (DAF2) em células do tipo RAW 264.7. Também foi investigado o papel que ferro lábil (LIP) exerce em tais processos. O estudo cinético mostrou que a nitrosação do DAF2 é dependente de superóxido intracelular e se processa por dois mecanismos distintos denominados nitrosilação oxidativa e nitrosação. Observou-se que o perfil cinético da nitrosaçao do DAF2 sofre uma transição passando de dependente para independente com relação à concentração de NO, quando a concentração de NO se aproxima de 100-110nM. Este perfil está relacionado com a dinâmica de recombinação entre NO e O2¯ que dispara todo o processo de nitrosação do DAF2. No trabalho fica claro que processos nitrosativos que ocorrem pelos mesmos mecanismos podem apresentar perfis cinéticos completamente diferentes dependendo da localização onde ocorre a recombinação entre NO e O2¯. O ponto mais interessante foi a constatação de que quelantes permeáveis à membranas biológicas estimulam a nitrosação do DAF2 intracelular. Este efeito é decorrente da remoção de LIP intracelular que, surpreendementemente, apresenta papel antinitrosativo nas condições experimentais estudadas. O papel incomum antinitrosativo apresentado por LIP é analizado do ponto de vista da reação entre LIP e ONOO¯ que tem como produto nitrito, uma espécie não nitrosante. Estes resultados podem alterar a forma como LIP é visto em processos oxidativos e nitrosativos.

Synthesis of α,β-diamino acid derivatives via asymmetric Mannich reactions of glycine imino esters catalyzed by a chiral phosphoramidite·silver complex

AgOTf·phosphoramidite complexes efficiently catalyze the enantioselective Mannich-type reaction between benzophenone-imine glycine methyl ester and N-tosyl aldimines in the absence of a base. The corresponding syn-adducts, which are the direct precursors of α,β-diamino acids, are obtained with moderate to good syn-diastereoselectivities (up to 9:1) and high enantioselectivities (up to 99% ee).

Copper(II) complexes with unsymmetrical pentadentate ed3a-type diamino-tricarboxylate ligands. Crystal structures, configurational analysis and DFT study of complexes

The O–O–N–N–O-type pentadentate ligands H3ed3a, H3pd3a and H3pd3p (H3ed3a stands ethylenediamine-N,N,N′-triacetic acid; H3pd3a stands 1,3-propanediamine-N,N,N′-triacetic acid and H3pd3p stands 1,3-propanediamine-N,N,N′-tri-3-propionic acid) and the corresponding novel octahedral or square-planar/trigonal-bipyramidal copper(II) complexes have been prepared and characterized. H3ed3a, H3pd3a and H3pd3p ligands coordinate to copper(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral in case of ed3a3− and intermediate square-pyramidal/trigonal-bipyramidal structure in case of pd3a3− and pd3p3−. A six coordinate, octahedral geometry has been established crystallographically for the [Mg(H2O)6][Cu(ed3a)(H2O)]2 · 2H2O complex and five coordinate square-pyramidal for the [Mg(H2O)5Cu(pd3a)][Cu(pd3a)] · 2H2O. Structural data correlating similar chelate Cu(II) complexes have been used for the better understanding the pathway: octahedral → square-pyramidal ↔ trigonal- bipyramid geometry. An extensive configuration analysis is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) programs have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data.

An extracellular signal-regulated kinase 2 survival pathway mediates resistance of human mesothelioma cells to asbestos-induced injury

We hypothesized that normal human mesothelial cells acquire resistance to asbestos-induced toxicity via induction of one or more epidermal growth factor receptor (EGFR) - linked survival pathways (phosphoinositol-3-kinase/AKT/ mammalian target of rapamycin and extracellular signal - regulated kinase [ERK] 1/2) during simian virus 40 (SV40) transformation and carcinogenesis. Both isolated HKNM-2 mesothelial cells and a telomerase-immortalized mesothelial line (LP9/TERT-1) were more sensitive to crocidolite asbestos toxicity than an SV40 Tag-immortalized mesothelial line (MET5A) and malignant mesothelioma cell lines (HMESO and PPM Mill). Whereas increases in phosphorylation of AKT (pAKT) were observed in MET5A cells in response to asbestos, LP9/TERT-1 cells exhibited dose-related decreases in pAKT levels. Pretreatment with an EGFR phosphorylation or mitogen-activated protein kinase kinase 1/2 inhibitor abrogated asbestos-induced phosphorylated ERK (pERK) 1/2 levels in both LP9/TERT-1 and MET5A cells as well as increases in pAKT levels in MET5A cells. Transient transfection of small interfering RNAs targeting ERK1, ERK2, or AKT revealed that ERK1/2 pathways were involved in cell death by asbestos in both cell lines. Asbestos-resistant HMESO or PPM Mill cells with high endogenous levels of ERKs or AKT did not show dose-responsive increases in pERK1/ERK1, pERK2/ERK2, or pAKT/AKT levels by asbestos. However, small hairpin ERK2 stable cell lines created from both malignant mesothelioma lines were more sensitive to asbestos toxicity than shERK1 and shControl lines, and exhibited unique, tumor-specific changes in endogenous cell death - related gene expression. Our results suggest that EGFR phosphorylation is causally linkedto pERK and pAKT activation by asbestos in normal and SV40 Tag - immortalized human mesothelial cells. They also indicate that ERK2 plays a role in modulating asbestos toxicity by regulating genes critical to cell injury and survival that are differentially expressed in human mesotheliomas.