Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Brain Dev ; 43(6): 705-713, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33610339

RESUMO

OBJECTIVE: To elucidate the clinical characteristics of Japanese pediatric patients with acquired demyelinating diseases (ADS), positive for myelin oligodendrocyte glycoprotein antibody (MOG-IgG), we conducted a nation-wide survey. METHODS: Information about pediatric patients under 18 years old with ADS was solicited with surveys sent to 323 facilities. In an initial survey, we asked whether the center had any patients with ADS, and the MOG-IgG serostatus of the patients. In a follow-up survey, we requested more precise information on patients with ADS. RESULTS: Initial survey: 263 replies providing information on 175 patients were received. MOG-IgG were examined in 78 patients and 54 of those (69%) were positive for MOG-IgG. Follow-up survey: The characteristic involvement was optic neuritis, with visual disturbance and optic pain as characteristic symptoms. The relapse rate was 44% in patients positive for MOG-IgG, which was higher than that in seronegative patients (38%). For acute phase treatments, corticosteroid (CS), plasma exchange, and intravenous immunoglobulin (IVIG) were useful. To prevent relapse, CS, intermittent IVIG, immunosuppressants, and monoclonal antibodies were useful, but the efficacies of disease modifying drugs were uncertain. Sequelae such as visual disturbance, cognitive impairment, motor dysfunction, and epilepsy were observed in 11% of patients with MOG-IgG. CONCLUSIONS: MOG antibody-associated diseases were found to be common among pediatric ADS patients. Since a variety of sequelae were observed in these patients, it is important to identify the appropriate treatment to ensure the best outcome. The presence of the MOG autoantibody should be taken into consideration as part of the diagnostic criteria for pediatric ADS.


Assuntos
Autoanticorpos/sangue , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central , Glicoproteína Mielina-Oligodendrócito/imunologia , Neurite Óptica , Adolescente , Aquaporina 4/imunologia , Criança , Pré-Escolar , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/etiologia , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/sangue , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/complicações , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/epidemiologia , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/imunologia , Epilepsia/epidemiologia , Epilepsia/etiologia , Feminino , Inquéritos Epidemiológicos , Humanos , Japão/epidemiologia , Masculino , Transtornos dos Movimentos/epidemiologia , Transtornos dos Movimentos/etiologia , Neurite Óptica/sangue , Neurite Óptica/complicações , Neurite Óptica/epidemiologia , Neurite Óptica/imunologia , Recidiva , Transtornos da Visão/epidemiologia , Transtornos da Visão/etiologia
2.
Zoolog Sci ; 38(1): 8-19, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33639713

RESUMO

Foam nests of frogs are natural biosurfactants that contain potential compounds for biocompatible materials, Drug Delivery System (DDS), emulsifiers, and bioremediation. To elucidate the protein components in the foam nests of Rhacophorus arboreus, which is an endemic Japanese frog species commonly seen during the rainy season, we performed amino acid analysis, SDS-PAGE electrophoresis, and matrix-assisted laser desorption/ionization mass spectrometry using intact foam nests. Many proteins were detected in these foam nests, ranging from a few to several hundred kDa, with both essential and non-essential amino acids. Next, we performed transcriptome analysis using a next-generation sequencer on total RNAs extracted from oviducts before egg-laying. The soluble foam nests were purified by LC-MS and analyzed using Edman degradation, and the identified N-terminal sequences were matched to the transcriptome data. Four proteins that shared significant sequence homologies with extracellular superoxide dismutase of Nanorana parkeri, vitelline membrane outer layer protein 1 homolog of Xenopus tropicalis, ranasmurfin of Polypedates leucomystax, and alpha-1-antichymotrypsin of Sorex araneus were identified. Prior to purification of the foam nests, they were treated with both a reducing reagent and an alkylating agent, and LC-MS/ MS analyses were performed. We identified 22 proteins in the foam nests that were homologous with proteinase inhibitors, ribonuclease, glycoproteins, antimicrobial protein and barrier, immunoglobulin-binding proteins, glycoprotein binding protein, colored protein, and keratin-associated protein. The presence of these proteins in foam nests, along with small molecules, such as carbohydrates and sugars, would protect them against microbial and parasitic attack, oxidative stress, and a shortage of moisture.


Assuntos
Anuros/metabolismo , Comportamento de Nidação/fisiologia , Oviductos/metabolismo , Proteoma , Animais , Anuros/genética , Feminino , Perfilação da Expressão Gênica
3.
Biomolecules ; 10(7)2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679686

RESUMO

The pits of Japanese apricot, Prunus mume Sieb. et Zucc., which are composed of stones, husks, kernels, and seeds, are unused by-products of the processing industry in Japan. The processing of Japanese apricot fruits generates huge amounts of waste pits, which are disposed of in landfills or, to a lesser extent, burned to form charcoal. Mume stones mainly consist of cellulose, hemicellulose, and lignin. Herein, we attempted to solubilize the wood-like carapace (stone) encasing the pit by subcritical fluid extraction with the aim of extracting useful chemicals. The characteristics of the main phenolic constituents were elucidated by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) analyses. The degrees of solubility for various treatments (190 °C; 3 h) were determined as follows: subcritical water (54.9%), subcritical 50% methanol (65.5%), subcritical 90% methanol (37.6%), subcritical methanol (23.6%), and subcritical isopropyl alcohol (14.4%). Syringaldehyde, sinapyl alcohol, coniferyl alcohol methyl ether, sinapyl alcohol methyl ether, 5-(hydroxymethyl)-2-furfural, and furfural were present in the subcritical 90% methanol extract. Coniferyl and sinapyl alcohols (monolignols) are source materials for the biosynthesis of lignin, and syringaldehyde occur in trace amounts in wood. Our current findings provide a solubilization method that allows the main phenolic constituents of the pits to be extracted under mild conditions. This technique for obtaining subcritical extracts shows great potential for further applications.


Assuntos
Metanol/análise , Extratos Vegetais/análise , Prunus/química , Cromatografia Líquida , Resíduos Industriais/análise , Extração Líquido-Líquido , Espectrometria de Massas , Metanol/química , Instalações de Eliminação de Resíduos
4.
Neuroscience ; 422: 12-20, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31705893

RESUMO

Oncostatin M (OSM) is a cytokine of the interleukin (IL)-6 family members. It induces blood-brain barrier (BBB) dysfunction by activating Janus-activated kinase (JAK) and signal transducer and activator of transcription (STAT) 3 pathways in brain endothelial cells. Brain pericytes located around microvessels are one of the BBB constituents. Pericytes work as a boundary surface between the blood circulation and brain parenchyma, and their functions are altered under pathophysiological conditions, leading to BBB dysregulation. However, it remains unknown whether pericytes are associated with OSM-induced BBB dysfunction. We demonstrated that pericyte exposure to OSM (100 ng/mL) elevated phosphorylation of STAT3, a main OSM signaling pathway, and that pericytes expressed OSM receptors (OSMRs) including OSMRß and glycoprotein 130. These results suggest that pericytes are able to respond to OSM. To determine the effects of OSM-reactive pericytes on BBB functions, rat brain endothelial cell (RBEC) monolayers were cultured with OSM-treated pericytes. The presence of pericytes exposed to 100 ng/mL of OSM for 48 h aggravated both the elevated permeability to sodium fluorescein and the lowered transendothelial electrical resistance which were induced by OSM in RBECs. This OSM-reactive pericyte-induced aggravation of lowered RBEC barrier function was reversed by ruxolitinib, a JAK inhibitor. These findings suggest that activated JAK/STAT3 signaling in pericytes contributes to OSM-produced BBB breakdown. Thus, OSM-reactive pericytes may have to be considered a characteristic machinery in the formation and progression of BBB breakdown under pathological conditions associated with increased OSM levels.


Assuntos
Barreira Hematoencefálica/fisiopatologia , Janus Quinases/metabolismo , Oncostatina M/farmacologia , Oncostatina M/fisiologia , Fator de Transcrição STAT3/metabolismo , Animais , Receptor gp130 de Citocina/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Nitrilas , Oncostatina M/antagonistas & inibidores , Subunidade beta de Receptor de Oncostatina M/metabolismo , Pericitos/efeitos dos fármacos , Pericitos/metabolismo , Fosforilação/efeitos dos fármacos , Cultura Primária de Células , Pirazóis/farmacologia , Pirimidinas , Ratos , Transdução de Sinais
5.
J Periodontal Res ; 54(6): 709-719, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31292965

RESUMO

BACKGROUND AND OBJECTIVE: Full-mouth scaling and root planing (FM-SRP) increases the systemic levels of inflammatory mediators via early inflammation but may be inhibited using an antimicrobial agent. This prospective intervention study evaluates the biological response and clinical effects of FM-SRP with and without systemically administered azithromycin (AZM). MATERIALS AND METHODS: A multicenter parallel randomized controlled and open-label trial. A central randomization center used computer-generated tables to allocate treatments. Sixty-three patients with moderate to severe generalized periodontitis (New American Academy of Periodontology Classification: Stage3 or 4, Grade B) were randomly assigned to receive FM-SRP with AZM (test group, n = 32) or FM-SRP without AZM (control group, n = 31). Clinical parameters and body temperature were measured, and subgingival plaque, peripheral blood, and gingival crevicular fluid were collected before and after treatment. Periodontopathic bacteria and IgG titers were measured by gingival crevicular fluid and peripheral blood. High-sensitivity assays were used to analyze systemic and local inflammatory markers, such as endotoxin, high-sensitive CRP (hs-CRP), and six inflammatory cytokines. Follow-up 6 weeks. RESULTS: The total number of bacteria and the number of Porphyromonas gingivalis and Prevotella intermedia were significantly lower in the test group after FM-SRP. IgG titers for P gingivalis significantly decreased after FM-SRP with AZM, and the body temperature increased significantly after FM-SRP without AZM. In the control group, serum hs-CRP, IFN-γ, IL-12p70, and IL-6 were significantly increased one day after treatment, but subsequently decreased below the original numerical value. In the test group, only hs-CRP showed a significant increase. CONCLUSIONS: FM-SRP resulted in similar improvements in clinical parameters with and without the use of AZM. Inflammatory mediators showed no difference between the two groups after FM-SRP treatment. The use of AZM was effective in preventing the elevation of body temperature after FM-SRP.


Assuntos
Azitromicina/uso terapêutico , Periodontite Crônica/terapia , Raspagem Dentária , Aplainamento Radicular , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
6.
Int J Dent ; 2018: 1748584, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29849634

RESUMO

OBJECTIVE: We evaluated the efficacies of antimicrobial photodynamic therapy (aPDT) and minocycline ointment (MO) on clinical and bacteriological markers and the local host inflammatory response. MATERIALS AND METHODS: A total of 30 patients with chronic periodontitis were randomly assigned to two groups. Selected periodontal pockets (probing depth 5-7 mm with bleeding on probing) were treated with aPDT or MO. Measurements of clinical parameters and the collection of gingival crevicular fluid (GCF) and subgingival plaque were performed at baseline, and at 1 and 4 weeks after treatment. Quantification of periodontopathic bacteria in the sulcus and a multiplex bead immunoassay of ten inflammatory cytokines in the GCF were performed. RESULTS: Local MO administration exhibited a significant decrease in scores for clinical parameters (P < 0.01) and a significant reduction in bacterial counts (P < 0.01) and interleukin-1ß and interferon-γ levels at 1 and 4 weeks after treatment (P < 0.01). No significant changes were observed in the aPDT group, except in clinical parameters. CONCLUSIONS: Although our study had some limitations, we found that while local administration of MO may slightly help to improve clinical, microbiological, and crevicular cytokine levels in periodontal pockets, aPDT did not show any effects. This trial is registered with the UMIN Clinical Trials Registry UMIN000013376.

7.
J Clin Biochem Nutr ; 60(3): 162-168, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28584397

RESUMO

Caffeic acid and (+)-catechin, which are abundantly contained in coffee and tea, are typical polyphenols. In order to know the relative magnitudes of antioxidant activity, effects by caffeic acid, (+)-catechin and their derivatives on the formation of 4-POBN/carbon-centered linoleic acid-derived radical adducts were examined in the control reaction mixture of linoleic acid with FeCl3 at 30°C for 168 h. In the presence of 1.0 mM of the polyphenols, peak to peak heights of the third ESR signal resulted in 7.7 ± 2.4% (n = 3) (caffeic acid), 145 ± 13% (n = 3) (quinic acid), 4.4 ± 0.0% (n = 3) (chlorogenic acid), 104 ± 4.4% (n = 3) (ferulic acid), 4.3 ± 0.0% (n = 3) (noradrenaline), 12.5 ± 10.9% (n = 3) (gallic acid), 38.1 ± 7.1% (n = 3) [(+)-catechin], 47.9 ± 11.7% (n = 3) [(-)-epicatechin], 56.5 ± 1.6% (n = 3) (epigallocatechin), 13.5 ± 1.7% (n = 3) (catechol) and 83.7 ± 7.8% (n = 3) (resorcinol) of the control reaction mixture. All the compounds with catechol moiety exerted potent inhibitory effects on the radical formation except for (+)-catechin, (-)-epicatechin and epigallocatechin. (+)-Catechin, (-)-epicatechin and epigallocatechin may not exert the inhibitory effect as much possibly because they are less stable compared with caffeic acid. The resorcinol moiety in these molecules may also weaken their antioxidant activity.

8.
Mol Pharmacol ; 87(2): 277-85, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25473119

RESUMO

Re-epithelialization begins early during skin wound healing and is regulated by various growth factors and cytokines. Angiotensin II promotes the migration of keratinocytes and thereby contributes to wound healing. We investigated the mechanism by which angiotensin II stimulates human keratinocyte migration. Angiotensin II-induced keratinocyte migration was inhibited by an angiotensin II type 1 receptor (AT1R) antagonist (candesartan) or an angiotensin II type 2 receptor (AT2R) antagonist (PD123319) as well as by depletion of AT1R or AT2R. A biased agonist for AT1R, [Sar(1),Ile(4),Ile(8)]angiotensin II, induced cell migration, whereas depletion of ß-arrestin2 inhibited angiotensin II-induced migration. Angiotensin II-induced migration was blocked by neutralizing antibodies to transforming growth factor-ß (TGF-ß) as well as by the TGF-ß receptor inhibitor SB431542. The amount of TGF-ß1 was increased in the culture medium of angiotensin II-treated cells, and this effect was inhibited by candesartan or PD123319. Both angiotensin II- and TGF-ß-induced cell migration were inhibited by neutralizing antibodies to the epidermal growth factor (EGF) receptor but not by those to EGF receptor ligands. Angiotensin II-induced phosphorylation of the EGF receptor, and this effect was inhibited by candesartan, PD123319, SB431542, or depletion of ß-arrestin2, but not by neutralizing antibodies to heparin-binding EGF-like growth factor. Our results indicate that ß-arrestin-dependent signaling downstream of AT1R as well as AT2R signaling are necessary for angiotensin II-induced keratinocyte migration, and that such signaling promotes generation of the active form of TGF-ß, consequent activation of the TGF-ß receptor, and transactivation of the EGF receptor by the TGF-ß receptor.


Assuntos
Angiotensina II/farmacologia , Movimento Celular/fisiologia , Queratinócitos/fisiologia , Transdução de Sinais/fisiologia , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Humanos , Queratinócitos/efeitos dos fármacos , Masculino , Transdução de Sinais/efeitos dos fármacos
9.
J Mol Cell Cardiol ; 76: 177-85, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25240642

RESUMO

The sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a)-phospholamban (PLN) system of sarcoplasmic reticulum plays a pivotal role in regulation of intracellular Ca(2+) cycling in ventricular cardiomyocytes. Given that Ca(2+) cycling is impaired in heart failure, proteins that contribute to this process are potential targets for the treatment of this condition. We have now isolated PLN-specific aptamers with a phosphorothioate-modified backbone from a library of RNA molecules containing a randomized 40-nucleotide sequence by application of the systematic evolution of ligands by exponential enrichment (SELEX) protocol with a fusion protein containing the cytoplasmic region of human PLN. One of these aptamers was shortened to a 30-nucleotide oligomer (RNA-Apt30) without loss of function. RNA-Apt30 showed a high affinity for the cytoplasmic region of PLN (Kd=11 nM), but it did not bind to the phosphorylated form of PLN or to a phosphomimetic mutant. It also increased SERCA2a activity in isolated cardiac SR vesicles with an EC50 of 18 nM by relieving PLN-mediated inhibition. Conjugation of RNA-Apt30 to a cell-penetrating peptide allowed its delivery into adult rat cardiomyocytes, in which it enhanced both Ca(2+) transients and contractile function. These effects of the aptamer were also apparent in the presence of the ß-adrenergic receptor antagonist propranolol. This cell-penetrating PLN aptamer may thus provide a basis for the development of new therapeutic agents for heart failure without the need for gene transfer or a change in endogenous protein expression.


Assuntos
Aptâmeros de Nucleotídeos/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Proteínas de Ligação ao Cálcio/metabolismo , Peptídeos Penetradores de Células/farmacologia , Miócitos Cardíacos/fisiologia , Animais , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Proteínas de Ligação ao Cálcio/química , Peptídeos Penetradores de Células/química , Células Cultivadas , Cães , Masculino , Dados de Sequência Molecular , Contração Miocárdica , Miócitos Cardíacos/efeitos dos fármacos , Ligação Proteica , Coelhos , Ratos Wistar , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo
10.
Biosci Biotechnol Biochem ; 77(8): 1623-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23924723

RESUMO

The fruit of mume, Japanese apricot (Prunus mume Sieb. et Zucc.), was evaluated for its phenolics content, high performance liquid chromatography (HPLC) profile and antioxidative activities. The phenolics content of mume fruit was relatively high, the flesh of fully matured fruit containing up to 1% of phenolics on a dry weight basis. Reflecting such a high content of phenolics, the ORAC (oxygen radical absorbance capacity) value for mume fruit flesh showed high values, ranging from 150 to 320 µmol/g Trolox equivalent, depending upon the stage of maturation. 5-O-Caffeoylqunic acid (chlorogenic acid), 3-O-caffeoylquinic acid and tetra-O-acylated sucrose-related compounds were isolated from the flesh of mume fruit, although many unknown peaks were also apparent in the HPLC chromatogram. An alkali hydrolysate comprised four main phenolic acids, caffeic acid, cis/trans-p-coumaric acid and ferulic acid. No flavonoids were observed in the analysis. These results suggest that the majority of phenolics in mume fruit were hydroxycinnamic acid derivatives.


Assuntos
Frutas/química , Hidroxibenzoatos/isolamento & purificação , Fenóis/isolamento & purificação , Prunus/química , Antioxidantes/química , Ácidos Cafeicos/química , Ácidos Cafeicos/isolamento & purificação , Ácido Clorogênico/química , Ácido Clorogênico/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Ácidos Cumáricos/química , Ácidos Cumáricos/isolamento & purificação , Flavonoides/química , Hidroxibenzoatos/química , Fenóis/química , Fenóis/classificação , Propionatos
11.
J Pharmacol Exp Ther ; 329(1): 57-63, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19158349

RESUMO

Calcium transport across the membrane of the sarcoplasmic reticulum (SR) plays an important role in the regulation of heart muscle contraction and relaxation. The sarco(endo)plasmic reticulum Ca(2+) ATPase (SERCA) 2a is responsible for Ca(2+) up-take by this organelle and is inhibited in a reversible manner by phospholamban, another SR membrane protein. Thus, alleviation of phospholamban-mediated inhibition of SERCA2a is a potential therapeutic option for heart failure and cardiomyopathy. We have now applied the systematic evolution of ligands by exponential enrichment protocol to a library of single-stranded DNA molecules containing a randomized 40-nucleotide sequence to isolate aptamers that bind phospholamban. One of the obtained aptamers, designated Apt-9, was found to specifically bind to the cytoplasmic region of phospholamban in vitro with high affinity (dissociation constant, approximately 20 nM). Apt-9 increased the Ca(2+)-dependent ATPase activity of cardiac SR vesicles but not that of SR vesicles from skeletal muscle in a concentration-dependent manner. It also shifted the Ca(2+) concentration-response curve for this ATPase activity to the left. These effects of Apt-9 were not mimicked by an oligonucleotide with a scrambled version of the Apt-9 sequence. Thus, our results indicate that Apt-9 activates SERCA2a by alleviating the inhibitory effect of phospholamban on this ATPase, and they suggest that phospholamban-specific aptamers warrant further investigation as potential therapeutic agents for heart failure and cardiomyopathy.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Aptâmeros de Nucleotídeos/química , Biotina/química , Proteínas de Ligação ao Cálcio/genética , ATPases Transportadoras de Cálcio/metabolismo , DNA/biossíntese , DNA/genética , Coração/efeitos dos fármacos , Humanos , Técnicas In Vitro , Ligantes , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Técnica de Seleção de Aptâmeros , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/enzimologia , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Especificidade por Substrato
12.
Chem Commun (Camb) ; (30): 3174-6, 2007 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-17653379

RESUMO

A photoresponsive single-handed double helical supramolecule composed of complementary strands bearing azobenzene moieties underwent a reversible trans-cis-isomerization regulated by photoirradiation, resulting in a change in its molecular length.


Assuntos
Amidinas/química , Compostos Azo/química , Ácidos Dicarboxílicos/química , Materiais Biomiméticos/química , Dicroísmo Circular , DNA/química , Isomerismo , Cinética , Espectroscopia de Ressonância Magnética , Conformação Molecular , Fotoquímica , Espectrometria de Massas por Ionização por Electrospray
14.
Org Lett ; 8(12): 2583-6, 2006 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-16737319

RESUMO

We describe novel optically active double helices consisting of complementary strands stabilized by amidinium-carboxylate salt bridges. The m-terphenyl groups of each strand are joined by trans-Pt(II) acetylide complexes with pendant PPh(3) ligands as the surrogate linker, which converts to cis counterparts by a ligand exchange reaction with cis-1,2-bis(diphenylphosphino)ethylene, resulting in the formation of double helices with different structures. Subsequent iodine-promoted reductive elimination on the Pt(II) atoms generates the fully organic, enantiomerically pure double helices. [structure: see text]

15.
J Am Chem Soc ; 128(21): 6806-7, 2006 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-16719458

RESUMO

We describe the construction of the first double-stranded metallosupramolecular helical polymers. We designed and synthesized a supramolecular duplex comprised of complementary m-terphenyl-based strands bearing a chiral amidine or achiral carboxylic acid together with two pyridine groups at the four ends. Supramolecular polymerization of the duplex with cis-PtPh2(DMSO)2 in 1,1,2,2-tetrachloroethane produced the double-stranded metallosupramolecular polymer with a controlled helicity of which the two complementary metallostrands are intertwined through the amidinium-carboxylate salt bridges. The structures and hydrodynamic dimensions of the metallosupramolecular polymers were characterized by 1H NMR, diffusion-ordered NMR, dynamic light scattering, absorption, and CD measurements. The polymeric structure was also visualized by atomic force microscopy.


Assuntos
Química Orgânica/métodos , Metais/química , Polímeros/química , Espectroscopia de Ressonância Magnética , Microscopia de Força Atômica , Estrutura Molecular , Compostos de Platina/química , Polímeros/síntese química , Piridinas/química , Sais
17.
J Org Chem ; 69(12): 4152-8, 2004 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-15176842

RESUMO

Naphthyl tetrahydroisoquinoline alkaloids, atropisomeric korupensamines A and B and ent-korupensamine B, were synthesized by syn-selective cross-coupling of a planar chiral arene chromium complex with naphthylboronic acid and subsequent axial isomerization or tricarbonylchromium migration to the inverted arene face as a key step. Palladium(0)-catalyzed cross-coupling of planar chiral arene chromium complex 12 with naphthylboronic acid 9 gave syn-biaryl coupling product 13. syn-Biaryl chromium complex 13 was heated in 1:1 mixture of di-n-butyl ether and 1,2-dichloroethane to give a face-inverted anti-biaryl chromium complex 14 without axial isomerization. Korupensamine A was synthesized from the syn-biaryl chromium complex 13 via o-formyl syn-biaryl chromium complex 10, and ent-korupensamine B was prepared from the face-inverted anti-biaryl chromium complex 14. On the other hand, difluoro-substituted syn-biaryl chromium complex 40 with a formyl group afforded anti-biaryl chromium complex 41 containing a rotated central bond by heating in xylene. The chromium-complexed fluorine atom was easily substituted with an isopropoxy group by nucleophilic substitution. Use of these reactions allowed (+)-2-bromo-3,5-difluorobenzaldehyde chromium complex (37) as a single chiral source to be converted to atropisomeric korupensamines A and B, respectively.


Assuntos
Compostos de Cromo/química , Isoquinolinas/síntese química , Naftalenos/síntese química , Estereoisomerismo
18.
J Org Chem ; 68(24): 9356-63, 2003 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-14629157

RESUMO

Axially chiral syn-biaryl chromium complexes having a coordinating heteroatom substituent at the benzylic position gave anti-biaryl chromium complexes 5 with inversion of the planar chirality by heating in a nonaromatic solvent, while syn-biaryl chromium complexes with an o-methyl or formyl substituent afforded axially isomerized anti-biaryl chromium complexes under heating in an aromatic solvent. syn-biaryl and both enantiomeric anti-biaryl chromium complexes with the o-formyl group were stereoselectively prepared from an identical planar chiral arene chromium complex as chiral source. The formyl group of the axially chiral chromium complexes was functionalized by radical cyclization and beta-lactam formation, and hetero-Diels-Alder reaction.

19.
J Org Chem ; 67(26): 9227-37, 2002 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-12492324

RESUMO

Samarium iodide-mediated cross-coupling of N-tosyl ferrocenylideneamine with planar chiral ferrocenecarboxaldehydes or benzaldehyde chromium complexes gave diastereoselectively the corresponding anti-beta-amino alcohol derivatives in good yields, while N-tosyl benzylideneamine produced syn-beta-amino alcohols by coupling with planar chiral arylaldehydes. Dynamic kinetic resolution of a configurationally equilibrated reactive species generated from achiral N-tosyl ferrocenilideneamine and benzylideneamine by reduction with samarium iodide was observed in the cross-coupling with planar chiral arylaldehydes giving both antipodes of beta-amino alcohols depending on the planar chirality. The obtained anti-beta-amino alcohol with the ferrocene ring was utilized as a chiral ligand for catalytic asymmetric reduction of acetophenone.

20.
Org Lett ; 4(5): 835-8, 2002 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-11869140

RESUMO

[reaction: see text] Samarium iodide mediated reductive cross-coupling of N-tosyl benzylideneamine with benzaldehydes or the corresponding chromium complexes gave syn-beta-amino alcohol derivatives. A dynamic kinetic resolution of a configurationally equilibrated reactive species occurred in the cross-coupling with planar chiral benzaldehyde chromium complexes.


Assuntos
Amino Álcoois/síntese química , Aminas/química , Benzaldeídos/química , Compostos de Benzilideno/química , Reagentes de Ligações Cruzadas/química , Estereoisomerismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA