Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros

País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Eur J Clin Invest ; 51(4): e13444, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33152138

RESUMO

BACKGROUND: There are no data on population-based epidemiological changes in acute myocarditis in Europe. Our aim was to evaluate temporal trends in incidence, clinical features and outcomes of hospital treated acute myocarditis (AM) in Spain from 2003 to 2015. METHODS: We conducted a retrospective longitudinal study using information of all hospital discharges of the Spanish National Health System. All episodes with a discharge diagnosis of AM from 1 January 2003 to 31 December 2015 were included. The risk-standardized in-hospital mortality ratio (RSMR) was calculated using a multilevel risk-adjustment model developed by the Medicare and Medicaid Services. Temporal trends for in-hospital mortality were modelled using Poisson regression analysis. RESULTS: A total of 11 147 episodes of AM were analysed, most of them idiopathic (94.7%). The rate of AM discharges increased along the period, from 13 to 30/million inhabitants/year (2003-2015), and this increase was statistically significant when weighted by age and sex (incidence rate ratio, IRR 1.06, 95% CI 1.04-1.08, P = .001). In-hospital crude mortality rate was 3.1%, diminishing significantly along 2003-2015 (IRR 0.95, 95% CI 0.92-0.99, P = .02). RSMR also significantly diminished along the period (IRR 0.95, 95% CI 0.92-0.99, P = .01). Renal failure (OR 7.03, 5.38-9.18, P = .001), liver disease (OR 4.61, 2.59-8.21, P = .001), pneumonia (OR 4.13, 2.75-6.20, P = .001) and heart failure (OR 1.91, 95% CI 1.47-2.47, P = .001) were the strongest independent factors associated with in-hospital mortality. CONCLUSIONS: Acute myocarditis is an uncommon entity, although hospital discharges have increased in Spain along the study period. Most of AM were idiopathic. Adjusted mortality was low and seemed to decrease from 2003 to 2015, suggesting an improvement in AM management.


Assuntos
Mortalidade Hospitalar , Hospitalização , Miocardite/epidemiologia , Doença Aguda , Adulto , Idoso , Comorbidade , Feminino , Insuficiência Cardíaca/epidemiologia , Humanos , Incidência , Hepatopatias/epidemiologia , Masculino , Pessoa de Meia-Idade , Miocardite/terapia , Pneumonia/epidemiologia , Insuficiência Renal/epidemiologia , Fatores de Risco , Espanha/epidemiologia
2.
Eur J Clin Invest ; 51(11): e13606, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34076253

RESUMO

BACKGROUND: Heart failure is one of the most pressing current public health concerns. However, in Spain there is a lack of population data. We aimed to examine thirteen-year nationwide trends in heart failure hospitalization, in-hospital mortality and 30-day readmission rates in Spain. METHODS: We conducted a retrospective observational study of patients discharged with the principal diagnosis of heart failure from The National Health System' acute hospitals during 2003-2015. The source of the data was the Minimum Basic Data Set. Temporal trends were modelled using Poisson regression analysis. The risk-standardized in-hospital mortality ratio was calculated using a multilevel risk adjustment logistic regression model. RESULTS: A total of 1 254 830 episodes of heart failure were selected. Throughout 2003-2015, the number of hospital discharges with principal diagnosis of heart failure increased by 61%. Discharge rates weighted by age and sex increased during the period [incidence rate ratio (IRR): 1.03; 95% confidence interval (95% CI): 1.03-1.03; P < .001)], although this increase was motivated by the increase in older age groups (≥75 years old). The crude mortality rate diminished (IRR: 0.99; 95% CI: 0.98-1, P < .001), but 30-day readmission rate increased (IRR: 1.05; 95% CI: 1.04-1.06; P < .001). The risk-standardized in-hospital mortality ratio did not change throughout the study period (IRR: 0.997; 95% CI: 0.992-1; P = .32). CONCLUSIONS: From 2003 to 2015, heart failure admission rates increased significantly in Spain as a consequence of the sustained increase of hospitalization in the population ≥75 years. 30-day readmission rates increased, but the risk-standardized in-hospital mortality ratio did not significantly change for the same period.


Assuntos
Insuficiência Cardíaca/epidemiologia , Mortalidade Hospitalar/tendências , Hospitalização/tendências , Readmissão do Paciente/tendências , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Fatores Sexuais , Espanha/epidemiologia
3.
Bioorg Med Chem ; 23(24): 7565-77, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26654469

RESUMO

To counteract bacterial resistance, we investigated the interruption of quorum sensing mediated by non-classical bioisosteres of the N-hexanoyl homoserine lactone with an azoline core. For this purpose, a set of selected 2-substituted azolines was synthesized, establishing the basis for a new protocol to synthesize 2-amino imidazolines. The synthesized compounds were evaluated as inhibitors of violacein production in Chromobacterium violaceum. Theoretical studies on bioisostere-protein interactions were performed using CviR. The results show that some azolines decreased violacein production, suggesting an antiquorum sensing profile against Gram-negative bacteria. Docking and molecular dynamic simulations together with binding free energy calculations revealed the exact binding and inhibitory profiles. These theoretical results show relationship with the in vitro activity of the azoline series.


Assuntos
4-Butirolactona/análogos & derivados , Antibacterianos/farmacologia , Chromobacterium/efeitos dos fármacos , Chromobacterium/fisiologia , Cinoxacino/farmacologia , Percepção de Quorum/efeitos dos fármacos , 4-Butirolactona/química , 4-Butirolactona/farmacologia , Antibacterianos/química , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Cinoxacino/química , Simulação de Dinâmica Molecular
4.
Int J Offender Ther Comp Criminol ; : 306624X231172644, 2023 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-37394821

RESUMO

This study examined predictors of individual general deviance (i.e., substance use, risk-taking, property crime, and interpersonal conflict/violence) within the context of COVID-19, focusing on the role of prior deviance, opportunities for crime, and levels of COVID-19- related stress. Our study showed that while some predictors relating to opportunity and strain were predictive of general deviance during the pandemic, few maintained statistical significance once controls for deviant behavior before the pandemic were included in the analyses, indicating the importance of within-individual behavioral stability over time. Further, respondents who participated in deviance prior to the pandemic were more likely to engage in other forms of criminal and high-risk activities during the pandemic. The close connections between criminal and high-risk behavior may imply that even if overall crime rates decreased during the pandemic, within-person behavioral patterns remained stable.

5.
J Prev Interv Community ; 51(4): 375-395, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38236583

RESUMO

Well-integrated and productive communities are an asset to the development and advancement of our nation, and they have an important role to play in planning, learning, and enforcing safety to enhance national and border security. REACH (Resilience, Education, Action, Commitment, and Humanity) is a community-based project housed at The University of Texas at El Paso that aims to prevent targeted violence and domestic terrorism in El Paso County. We integrated three frameworks (i.e., Whole Community Preparedness, Socio-Ecological Model, and Global Citizen Education) to involve local residents in efforts to combat and mitigate targeted violence. REACH had two goals: to (1) prevent targeted violence and domestic terrorism through education, outreach, and community capacity-building aimed at identifying and deterring radicalization (primary prevention) and (2) reduce the short-term and long-term impact and prevent re-occurrence of targeted violence and domestic terrorism (secondary and tertiary prevention). Overall, our project served 8,934 participants directly and reached many more through our media cavmpaigns and outreach efforts during our 2 years of project implementation (2021-2023). Our project design may serve as an implementation model for other community-based projects on the U.S.-Mexico border and can be replicated with other target populations in the U.S. Insights and lessons learned from this project are discussed.


Assuntos
Violência , Humanos , México , Texas
6.
Bioorg Chem ; 45: 29-35, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23064125

RESUMO

A series of bi- and tricyclic ß-lactam compounds was synthesized and evaluated as inhibitors of cleavage of synthetic substrates in vitro by the serine proteases Human Leukocyte Elastase (HLE), Human Leukocyte Proteinase 3 (HLPR3) and Porcine Pancreatic Elastase (PPE). The obtained results have permitted us to describe a homobenzocarbacephem compound as HLE and HLPR3 inhibitor, to observe the positive effect that the styryl group exerts on the HLE inhibitory activity in polycyclic ß-lactam compounds and to conclude that the hydroxyl function decreases the HLE inhibitory activity or rules it out completely.


Assuntos
Elastase de Leucócito/antagonistas & inibidores , Mieloblastina/antagonistas & inibidores , Elastase Pancreática/antagonistas & inibidores , Inibidores de Proteases/química , beta-Lactamas/química , Animais , Cefalosporinas/química , Humanos , Elastase de Leucócito/metabolismo , Mieloblastina/metabolismo , Elastase Pancreática/metabolismo , Inibidores de Proteases/síntese química , Suínos , beta-Lactamas/síntese química
7.
Int J Mol Sci ; 13(2): 1284-1299, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22408391

RESUMO

A series of selected 2-substituted imidazolines were synthesized in moderate to excellent yields by a modification of protocols reported in the literature. They were evaluated as potential non-classical bioisosteres of AHL with the aim of counteracting bacterial pathogenicity. Imidazolines 18a, 18e and 18f at various concentrations reduced the violacein production by Chromobacterium violaceum, suggesting an anti-quorum sensing profile against Gram-negative bacteria. Imidazoline 18b did not affect the production of violacein, but had a bacteriostatic effect at 100 µM and a bactericidal effect at 1 mM. Imidazoline 18a bearing a hexyl phenoxy moiety was the most active compound of the series, rendering a 72% inhibitory effect of quorum sensing at 100 µM. Imidazoline 18f bearing a phenyl nonamide substituent presented an inhibitory effect on quorum sensing at a very low concentration (1 nM), with a reduction percentage of 28%. This compound showed an irregular performance, decreasing inhibition at concentrations higher than 10 µM, until reaching 100 µM, at which concentration it increased the inhibitory effect with a 49% reduction percentage. When evaluated on Serratia marcescens, compound 18f inhibited the production of prodigiosin by 40% at 100 µM.


Assuntos
Acil-Butirolactonas , Chromobacterium/metabolismo , Percepção de Quorum/efeitos dos fármacos , Serratia marcescens/metabolismo , Acil-Butirolactonas/síntese química , Acil-Butirolactonas/química , Acil-Butirolactonas/farmacologia , Indóis/metabolismo , Prodigiosina/biossíntese
8.
Sci Prog ; 105(1): 368504221075482, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35191340

RESUMO

After a catastrophic failure of the weld of the anchoring element of one cable in a stayed bridge, a non-destructive inspection was required to evaluate the weld condition of the 111 remaining anchoring elements to prevent future and similar failures. This examination was quite complicated since the anchoring elements are partially embedded in the reinforced concrete tower, and the weld is fully integrated into the concrete. Considering that direct access to the weld was not possible, acoustic emissions (AE) were a feasible alternative for these inspections. This study describes the inspection method, from laboratory tests simulating actual conditions for calibration to field tests for the method's tuning and evaluation. The AE inspection results are presented, and welds' condition is classified according to the acoustic energy, measured through a severity index and graded from a zonal intensity plot. Two structural elements were selected for concrete demolition to expose the weld for penetrant and ultrasonic inspections to correlate measurements of the actual condition of the welds and their defect size. Because of the analysis, welds are identified for immediate repair and the rest for AE monitoring to evaluate defect evolution through the increase of the severity index.

9.
Eur J Med Chem ; 43(7): 1432-7, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18063443

RESUMO

The alkylation reaction of 2,2'-diseleno and 4,4'-diseleno-bis(benzoic acid) derivatives in the presence of sodium borohydride and alkyl halides allowed the synthesis of various new o- and p-alkylselenenylated benzoic acid derivatives in good yields. The anti-inflammatory activity of selected selenide derivatives on granuloma induced by subcutaneous implantation of cotton pellets in Wistar rats was examined. Selenium derivatives 2a, 2c and 2e showed anti-inflammatory activity although to a lesser extent as compared to indomethacin, however they were found less toxic than the latter.


Assuntos
Anti-Inflamatórios/síntese química , Anti-Inflamatórios/farmacologia , Compostos de Selênio/síntese química , Compostos de Selênio/farmacologia , Animais , Anti-Inflamatórios/química , Feminino , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Ratos , Ratos Wistar , Compostos de Selênio/química
10.
Rev Esp Cardiol (Engl Ed) ; 71(2): 86-94, 2018 Feb.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-28697925

RESUMO

INTRODUCTION AND OBJECTIVES: Hereditary pulmonary veno-occlusive disease (PVOD) has been associated with biallelic mutations in EIF2AK4 with the recent discovery of a founder mutation in Iberian Romani patients with familial PVOD. The aims of this study were phenotypical characterization and survival analysis of Iberian Romani patients with familial PVOD carrying the founder p.Pro1115Leu mutation in EIF2AK4, according to their tolerance to pulmonary vasodilators (PVD). Familial genetic screening was conducted, as well as assessment of sociocultural determinants with a potential influence on disease course. METHODS: Observational study of Romani patients with familial PVOD included in the Spanish Registry of Pulmonary Arterial Hypertension. Genetic screening of EIF2AK4 was performed in index cases and relatives between November 2011 and July 2016 and histological pulmonary examination was carried out in patients who received a lung transplant or died. The patients were divided into 2 groups depending on their tolerance to PVD, with comparison of baseline characteristics and survival free of death or lung transplant. RESULTS: Eighteen Romani patients were included: 9 index cases and 9 relatives. The biallelic founder mutation in EIF2AK4 was found in all affected cases and 2 unaffected relatives. Family screening showed 34.2% of healthy heterozygotes, high consanguinity, young age at childbirth, and frequent multiparity. Prognosis was bleak, with significant differences depending on tolerance to PVD. CONCLUSIONS: We describe 2 phenotypes of hereditary PVOD depending on tolerance to PVD, with prognostic impact and familial distribution. Consanguinity may have a negative impact on the transmission of PVOD, with familial genetic screening showing high effectiveness.


Assuntos
DNA/genética , Mutação , Proteínas Serina-Treonina Quinases/genética , Pneumopatia Veno-Oclusiva/genética , Adulto , Análise Mutacional de DNA , Feminino , Humanos , Masculino , Linhagem , Proteínas Serina-Treonina Quinases/metabolismo , Pneumopatia Veno-Oclusiva/congênito , Pneumopatia Veno-Oclusiva/mortalidade , Espanha/epidemiologia , Taxa de Sobrevida/tendências , Adulto Jovem
11.
ACS Appl Mater Interfaces ; 9(7): 5927-5936, 2017 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-28106371

RESUMO

PtCo alloy catalysts for high temperature PEMFCs (protonic exchange membrane fuel cells) were synthesized on a novel noncarbonaceous support (SiCTiC) using the impregnation method with NaBH4 as the reducing agent at different synthesis temperatures to evaluate the effect of this variable on their physicochemical and electrochemical properties. The catalysts were characterized by inductively coupled plasma optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscope-energy dispersive X-ray,and temperature-programmed reduction. In addition, the electrochemical characterization (i.e., cyclic voltammetry, oxygen reduction reaction, and chronoamperometry) was carried out with a rotating disk electrode. For the cyclic voltammetry investigation, 400 cycles were performed in hot phosphoric acid and a half-cell to evaluate the stability of the synthesized catalysts. The catalyst synthesized on SiCTiC exhibited excellent durability compared to the catalyst synthesized on a Vulcan support. In addition, all synthesized catalysts exhibited better catalytic activity than that of the PtCo/C catalysts. The best results were observed for the catalyst synthesized at 80 °C due to its shorter Pt-Pt nearest-neighbor and higher alloy degree. Finally, a preliminary stability test was conducted in an HT-PEMFC, and promising results in terms of stability and performance were observed.

12.
ChemSusChem ; 9(10): 1187-93, 2016 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-27076055

RESUMO

This work evaluates the use of carbon nanospheres (CNS) in microporous layers (MPL) of high temperature proton exchange membrane fuel cell (HT-PEMFC) electrodes and compares the characteristics and performance with those obtained using conventional MPL based on carbon black. XRD, hydrophobicity, Brunauer-Emmett-Teller theory, and gas permeability of MPL prepared with CNS were the parameters evaluated. In addition, a short life test in a fuel cell was carried out to evaluate performance under accelerated stress conditions. The results demonstrate that CNS is a promising alternative to traditional carbonaceous materials because of its high electrochemical stability and good electrical conductivity, suitable to be used in this technology.


Assuntos
Carbono/química , Fontes de Energia Elétrica , Temperatura Alta , Membranas Artificiais , Nanosferas/química , Prótons , Eletrodos , Porosidade
13.
Acta Trop ; 155: 6-10, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26657313

RESUMO

Giardiasis is a major diarrheal disease found throughout the world, the causative agent being the flagellate protozoan Giardia intestinalis. Infection is more common in children than in adults. The appearance of drug resistance has complicated the treatment of several parasitic diseases, including giardiasis. Thus, the aim of this investigation was to make an in vitro evaluation of the antigiardia response of synthetic derivatives 2-aryl-3-hydroxymethylimidazo[1,2-a]pyridines 1 and -pyrimidines 2 against trophozoites of Giardia lamblia WB, in comparison with the reference drug, albendazole. Additionally, the synergistic action of albendazole in combination with each of the most active 2-aryl-3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines was also assessed. Based on the IC50 values obtained, the best anti-Giardia activity was provided by the 3-hydroxymethyl-4-fluorophenylimidazo[1,2-a]pyrimidine derivative 2c and the corresponding imidazo[1,2-a]pyrimidine with the p-tolyl substituent 2d, followed by 2a and 2b. These four compounds showed effectiveness at a concentration similar to that of albendazole. Regarding synergism, the IC50 of the combination of albendazole with 2a, 2b or 2c gave the best anti-Giardia action, showing greater efficacy than albendazole alone. Hence, G. lamblia WB showed high susceptibility to some 2-aryl-3-hydroxymethyl imidazo[1,2-a] pyrimidines, which acted synergistically when used in combination with albendazole.


Assuntos
Albendazol/farmacologia , Antiprotozoários/farmacologia , Giardia lamblia/efeitos dos fármacos , Giardíase/tratamento farmacológico , Piridinas/farmacologia , Pirimidinas/farmacologia , Animais , Sinergismo Farmacológico , Humanos , Concentração Inibidora 50
14.
Toxicol In Vitro ; 19(8): 1045-50, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15963680

RESUMO

Several nitroimidazole derivatives were synthesized and tested as possible trichomonicidal agents. A fast, simple, practical and reliable in vitro colorimetric method was applied to the screening of the nitroimidazole derivatives anti-trichomonas activity. The colorimetric technique was based on the use of Alamar blue as a redox-indicator. The test was carried out both qualitatively (minimal inhibitory concentration determined by naked eye observation) and quantitatively (fluorometric determination of 50% and 90% inhibitory concentrations), the latter took advantage of the dye fluorometric properties. The performance of the method was excellent affording an exactitude 97.86% and a reproducibility of 95% and no interference of the trichomonas-culture medium was observed during the test. Some of the nitroimidazole compounds tested showed a fair trichomonicidal activity, however none of them was as active as the model compound, metronidazole.


Assuntos
Antitricômonas/toxicidade , Nitroimidazóis/toxicidade , Oxazinas , Trichomonas vaginalis/efeitos dos fármacos , Xantenos , Animais , Bioensaio , Colorimetria , Fluorometria , Indicadores e Reagentes , Oxirredução
15.
Acta Chim Slov ; 62(3): 679-88, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26454603

RESUMO

A computational Petra/Osiris/Molinspiration/DFT(POM/DFT) based model has been developed for the identification of physico-chemical parameters governing the bioactivity of ruthenium-staurosporine complexes 2-4 containing an antitumoral-kinase (TK) pharmacophore sites. The four compounds 1-4 analyzed here were previously screened for their antitumor activity, compounds 2 and 4 are neutral, whereas analogue compound 3 is a monocation with ruthenium(II) centre. The highest anti- antitumor activity was obtained for compounds 3 and 4, which exhibited low IC(50) values (0.45 and 8 nM, respectively), superior to staurosporine derivative (pyridocarbazole ligand 1, 150 · 10(3) nM). The IC(50) of 3 (0.45 nM), represents 20,000 fold increased activity as compared to staurosporine derivative 1. The increase of bioactivity could be attributed to the existence of pi-charge transfer from metal-staurosporine to its (CO(δ)--NH(δ+)) antitumor pharmacophore site.

16.
Toxicol In Vitro ; 18(3): 319-24, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15046779

RESUMO

Metronidazole (MTZ) and other nitroimidazole derivatives have been extensively used to treat infections caused by protozoa and anaerobic bacteria. However, the need for new derivatives with similar therapeutic activity but lower toxicity to human beings prevails. On this purpose, three metronidazole analogues were synthesized, namely: 1-(p-methylphenacyl)-2-methyl-4-nitro imidazole (CPMe), 1-(p-methoxyphenacyl)-2-methyl-4-nitroimidazole (CPMeO), and 1-(p-fluorphenacyl)-2-methyl-4-nitroimidazole (CPF), which at low concentrations (0.5-2 microg/ml) showed a higher activity against Entamoeba histolytica than MTZ (3-6 microg/ml). The aim of this work was to investigate the cytogenetic effect of the three MTZ analogues on human lymphocyte cultures with and without metabolic activation in vitro, using the sister chromatid exchange test (SCE), comparatively with MTZ. The effect of the compounds on the cell proliferation kinetics (CPK) measured by the replication index (RI) and the cytotoxic effect in the mitotic index (MI) was evaluated as well. The SCE frequencies with and without S9 metabolic activation in treated and control lymphocytes showed no significant statistical differences. However when metabolic activation was involved a significant increase in the amount of third division metaphases provoked the CPK increased significantly with all the tested compounds. The RI showed similar behaviour, except for compound CPF.


Assuntos
Anti-Infecciosos/toxicidade , Ciclo Celular/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Metronidazol/análogos & derivados , Metronidazol/síntese química , Metronidazol/farmacocinética , Metronidazol/toxicidade , Anti-Infecciosos/farmacocinética , Biotransformação , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Análise Citogenética , Humanos , Linfócitos/citologia , Linfócitos/ultraestrutura , Índice Mitótico , Troca de Cromátide Irmã
17.
Chem Cent J ; 7(1): 20, 2013 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-23363878

RESUMO

BACKGROUND: The proton at position 5 of imidazo[1,2-a]pyridines substituted with an angular electron withdrawing group (EWG) at position 3, shows an unusual downfield chemical shift, which is usually explained in terms of a peri effect. However usage of this term is sometimes confusing. In this investigation, it is proposed that the aforementioned shift is in fact a combination of several factors: Anisotropy, long-distance mesomerism and an attractive intramolecular interaction of the electrostatic hydrogen bond type. RESULTS: Theoretical calculations were performed aimed to obtain evidence of the existence of an intramolecular non-bonding interaction between H-5 and the oxygen atom of the EWG. Results derived from conformational and vibrational analysis at the DFT B3LYP/6-311++G(d,p) level of theory, the determination of Bond Critical Points derived from AIM theory, and the measurement of some geometrical parameters, support the hypothesis that the higher stability of the prevailing conformation in these molecules (that in which the oxygen of the EWG is oriented towards H-5) has its origin in an intramolecular interaction. CONCLUSION: Computational calculations predicted correctly the conformational preferences in angular 3-π-EWG-substituted imidazo[1,2-a]pyridines. The existence of an electrostatic hydrogen bond between H-5 and the oxygen atom of the π-EWG was supported by several parameters, including X-ray crystallography. The existence of such structural array evidently impacts the H-5 chemical shift.

18.
Chem Cent J ; 6(1): 83, 2012 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-22871219

RESUMO

BACKGROUND: Imidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity. RESULTS: Compounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wavelengths, whereas the former emitted purple light. CONCLUSION: It was concluded that in most cases the hydroxymethyl moiety did act as an enhancer of the fluorescence intensity, however, a comparison made with the fluorescence emitted by 2-aryl imidazo[1,2-a]azines revealed that in some cases the hydroxymethyl substituent decreased the fluorescence intensity.

20.
Nat Prod Res ; 24(13): 1274-81, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20645216

RESUMO

An expeditious synthesis of 5,7-dihydroxy-6-methylphthalide from open-chain precursors is described. The key intermediates, synthons 3 and 4, were readily obtained from accessible materials and were further transformed to a common precursor, a five-membered lactone derivative, via an intramolecular Michael addition. Lactone 2 was aromatised to the phthalide system under basic conditions. The process thus constitutes a formal synthesis of the phthalide framework.


Assuntos
Benzofuranos/síntese química , Anidridos Ftálicos/síntese química , Benzofuranos/química , Lactonas/química , Estrutura Molecular , Espectrofotometria Infravermelho
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA