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1.
Ear Nose Throat J ; : 1455613231168487, 2023 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-36976171

RESUMEN

OBJECTIVE: The benefit of a nasal corticosteroid in the treatment of persistent post-infectious smell disorders is not as clear in previous studies as is assumed for olfactory training. This study would therefore like to describe the treatment strategies using the example of a persistent olfactory dysfunction as a result of a proven infection with SARS-CoViD-2-virus. METHODS: Twenty patients (average age of 33.9 ± 11.9 years) with hyposmia were included in this study from December 2020 to July 2021. Every second patient received additionally a nasal corticosteroid. The two resulting randomized groups of equal size were screened with the TDI test, a 20-item taste powder test for the assessment of retronasal olfaction and otorhinolaryngological examination. The patients were asked to train twice daily using a standardized odor training kit and followed up after 2 months and 3 months, respectively. RESULTS: We documented a significant overall improvement in olfactory ability over the investigation period in both groups. While the TDI score steadily increased on average under the combination therapy, the rise under olfactory training alone was initially steeper. This short-term interaction effect over mean two months was not statistically significant. According to Cohen, however, a moderate effect (eta2 = 0.055, Cohen`s d = 0.5) can still be assumed. This effect could be explained by a possibly higher compliance at the beginning of the sole olfactory training due to the lack of further drug treatment offers. When the training intensity decreases, the recovery of the sense of smell stagnates. Adjunctive therapy ultimately outweighs this short-term benefit. CONCLUSIONS: The results reinforce the recommendation of early and consistent olfactory training on patients with dysosmia due to COVID-19. For continuous improvement of the sense of smell, an accompanying topical treatment seems at least to be worth consideration. The results should be optimized with larger cohorts and using new objective olfactometric methods.

2.
Prog Urol ; 32(10): 711-716, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35715252

RESUMEN

AIM: To evaluate the correlation between the Expanded Disability Status Scale (EDSS) in multiple sclerosis (MS) subjects, and the severity of lower urinary tract symptoms (LUTS), the bother caused by these symptoms and subjects' quality of life (QoL). MATERIAL AND METHODS: This cross-sectional study included 50 subjects with persistent LUTS secondary to MS who were recruited from the registry of a national NGO, between October 2017 and November 2019. Subjects with a history of any disease besides MS that could otherwise explain the presence of LUTS, as well as those with other neurological conditions were excluded. Information including MS duration, subjects' EDSS, voiding and storage LUTS, voiding symptoms' subscore of the International Prostate Symptom Score (IPSS-V), Overactive Bladder Symptom Scores (OABSS), Urinary Bothersome Questionnaire in Multiple Sclerosis (UBQMS), and urologic QoL (SF-Qualiveen) was gathered. Correlations between these scores were assessed using Spearman's bivariate correlations. Wilcoxon's signed rank test was used to evaluate the difference of impact between voiding and storage LUTS on bother of subjects. RESULTS: The median disease duration was 7±5.8years and the predominant lower urinary symptom was urgency (82%). Median OABSS and IPSS-V were respectively 8±3.8 and 8±3. Subjects were significantly more bothered from storage than voiding symptoms (2 vs. 1.6; P=0.03), and their QoL was directly affected by storage LUTS. Urgency urinary incontinence had the highest positive correlation with SFQ (r=0.542; P<0.01). MS duration and urologic QoL measured by SF-Q were negatively correlated (r=-0.345; P=0.01). CONCLUSION: In MS patients with LUTS, urologic QoL is mainly affected by storage urinary symptoms. Physicians should use a holistic approach to reduce the risk of complications in these patients, by controlling both voiding and storage symptoms, in particular urgency urinary incontinence that mostly affects patient's QoL.


Asunto(s)
Síntomas del Sistema Urinario Inferior , Esclerosis Múltiple , Vejiga Urinaria Hiperactiva , Incontinencia Urinaria , Estudios Transversales , Humanos , Masculino , Calidad de Vida
4.
Mult Scler Relat Disord ; 41: 101997, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32113183

RESUMEN

BACKGROUND: Multiple sclerosis (MS) is often associated with fatigue, with an increased prevalence of sleep disorders compared to the general population, notably restless legs syndrome (RLS). The aim of this study was to evaluate the prevalence and severity of RLS as well the co-occurrence of spinal demyelination lesions in patients with MS in Lebanon. METHODS: In this cross-sectional study, we consulted the MS database of the Lebanese association against Multiple Sclerosis and sent out questionnaires to 300 MS patients to screen then confirm the presence of RLS. The final sample included 28 MS participants with confirmed RLS. We conducted further questionnaires to collect demographic data, screen for comorbidities, gather spinal MRI results, and evaluate the severity of both diseases (using the EDSS and the JHRLSS). RESULTS: Prevalence of RLS was 15% among MS patients in our study. 46.4% of RLS-affected MS patients had spinal cord demyelination lesions on their MRIs. Participants with MRI lesions had a lower severity score on the JHRLSS (p = 0.088). No association was found between the EDSS results and JHRLSS, demographic data, or comorbidities. CONCLUSION: Restless legs syndrome is commonly found among patients with multiple sclerosis in Lebanon, is underdiagnosed, and ought to be systematically evaluated for in order to improve the patients' quality of life.


Asunto(s)
Fatiga/etiología , Esclerosis Múltiple/complicaciones , Esclerosis Múltiple/patología , Síndrome de las Piernas Inquietas/etiología , Médula Espinal/patología , Adulto , Estudios Transversales , Fatiga/epidemiología , Femenino , Humanos , Líbano/epidemiología , Imagen por Resonancia Magnética , Masculino , Esclerosis Múltiple/epidemiología , Prevalencia , Síndrome de las Piernas Inquietas/epidemiología , Índice de Severidad de la Enfermedad , Médula Espinal/diagnóstico por imagen
5.
RSC Adv ; 10(66): 40127-40135, 2020 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-35520832

RESUMEN

A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to the results showed in our previous report. The physicochemical characterization of these new nitrones by electron spin resonance (ESR) demonstrated their high capability to trap and stabilize different atom centered free radicals generated by the Fenton reaction. Additionally, we intensely studied them in terms of their physicochemical properties. Kinetic studies, including the use of a method based on competition and the hydroxyl adduct decay, gave the corresponding rate constants and half-lives at the physiological pH of these newly synthesized nitrones. New nitrones derived from quinoxaline 1,4-dioxide heterocycles were more suitable than DMPO to trap hydroxyl free radicals with a half-life longer than two hours. We explain some of the results using computational chemistry through density functional theory (DFT).

6.
Carbohydr Polym ; 204: 170-181, 2019 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-30366529

RESUMEN

Association constants and thermodynamicsparameters on inclusion of four 3-amido coumarins that present trypanocidal activity, into 6-amino-ß-cyclodextrin (1:1 stoichimetry) were determined. In addition, pure homopolymeric-α-l-guluronate fraction prepared by partial hydrolysis of sodium alginate from Sub-Antarctic Kelp Durvillaea antarctica was conjugated with 6-amino-ß-cyclodextrin (64% yield). To glycoconjugates, 3-amido coumarins were incorporated (73% of encapsulation) and supramolecular hydrogels were prepared by gelation with Ca2+ ions. The trypanocidal activity of the inclusion complexes increased by 10%. Likewise, an increase in diffusion in artificial membrane was observed (13%). It was found that the inclusion complexes increased the variation of the mitochondrial potential of T. cruzi (17%). The lowest release of substituted amidocoumarins (ACS) from supramolecular hydrogels occurred at pH 1.2 whereas the maximum release (34%) was observed at pH 8.0. Encapsulation of lipophilic bioactive compounds in supramolecular hydrogels allows the generation of release systems sensitive to pH with potential application in biomedicine.

7.
Carbohydr Polym ; 199: 304-313, 2018 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-30143133

RESUMEN

This work is related to the structural characterization of the sulfated polysaccharide from Lessonia sp and the study of its antioxidant and antiparasitic properties. Sequential extraction afforded D-mannitol as the only low MW sugar alcohol. Extraction with 2% CaCl2 afforded in 3.0% yield, a sulfated fucan (SF). Its major fraction (48.5% yield), isolated by ion-exchange chromatography corresponds to a linear polymer of α-l-fucopyranosil residues linked 1→3, sulfated at the O-4 and partially at O-2 positions. By alkaline extraction, sodium alginate (10.3% yield) was obtained. The antioxidant capacity of SF by ESR showed high elimination index (IC50, mg/mL) of hydroxyl (0.27), alkoxy (10.05), and peroxyl (82.88) radicals in relation to commercial mannitol. SF showed activity against the epimastigote form of Trypanosoma cruzi parasite (250 µg/mL) and low cytotoxicity in murine cells (367 µg/mL). The elimination capacity of radicals in aqueous medium of SF would allow its potential biomedical application.


Asunto(s)
Depuradores de Radicales Libres/farmacología , Polisacáridos/farmacología , Ésteres del Ácido Sulfúrico/farmacología , Tripanocidas/farmacología , Animales , Secuencia de Carbohidratos , Depuradores de Radicales Libres/química , Depuradores de Radicales Libres/aislamiento & purificación , Ratones , Phaeophyceae/química , Polisacáridos/química , Polisacáridos/aislamiento & purificación , Células RAW 264.7 , Ésteres del Ácido Sulfúrico/química , Ésteres del Ácido Sulfúrico/aislamiento & purificación , Tripanocidas/química , Tripanocidas/aislamiento & purificación , Trypanosoma cruzi/efectos de los fármacos
8.
Free Radic Res ; 48(12): 1473-84, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25236566

RESUMEN

A series hydroxycinnamic and gallic acids and their derivatives were studied with the aim of evaluating their in vitro antioxidant properties both in homogeneous and in cellular systems. It was concluded from the oxygen radical absorbance capacity-fluorescein (ORAC-FL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and cyclic voltammetry data that some compounds exhibit remarkable antioxidant properties. In general, in homogeneous media (DPPH assay), galloyl-based cinnamic and benzoic systems (compounds 7-11) were the most active, exhibiting the lowest oxidation potentials in both dimethyl sulfoxide (DMSO) and phosphate buffer. Yet, p-coumaric acid and its derivatives (compounds 1-3) disclosed the highest scavenging activity toward peroxyl radicals (ORAC-FL assay). Interesting structure-property- activity relationships between ORAC-FL, or DPPH radical, and redox potentials have been attained, showing that the latter parameter can be a valuable antioxidant measure. It was evidenced that redox potentials are related to the structural features of cinnamic and benzoic systems and that their activities are also dependent on the radical generated in the assay. Electron spin resonance data of the phenoxyl radicals generated both in DMSO and phosphate buffer support the assumption that radical stability is related to the type of phenolic system. Galloyl-based cinnamic and benzoic ester-type systems (compounds 9 and 11) were the most active and effective compounds in cell-based assays (51.13 ± 1.27% and 54.90 ± 3.65%, respectively). In cellular systems, hydroxycinnamic and hydroxybenzoic systems operate based on their intrinsic antioxidant outline and lipophilic properties, so the balance between these two properties is considered of the utmost importance to ensure their performance in the prevention or minimization of the effects due to free radical overproduction.


Asunto(s)
Antioxidantes/metabolismo , Ácidos Cumáricos/metabolismo , Técnicas Electroquímicas , Hidroxibenzoatos/metabolismo , Animales , Antioxidantes/química , Línea Celular , Ácidos Cumáricos/química , Espectroscopía de Resonancia por Spin del Electrón , Hidroxibenzoatos/química , Ratones , Estructura Molecular
9.
Curr Med Chem ; 20(37): 4731-43, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23834188

RESUMEN

The study of antioxidants and radicals has always been a complex task due to the special characteristics of these species such as reactions at low concentrations and short half-lives. Current techniques do not always produce good results and in some cases they can only be applied in chemical models. From this point of view, the development of electron spin resonance (ESR) has allowed the study of the antioxidant capacity of a wide variety of compounds and the detection of radicals in the reactions in which they are involved. The DPPH technique allows only the study of antioxidants in pure chemical models. The ORAC-ESR assay, based on the spin trapping technique, emerges as an interesting tool for identifying and quantifying the antioxidant capacity of different samples. Furthermore, the spin trapping technique allows us to characterize radicals in in vivo/ex vivo models. The present review discusses the current available techniques associated with ESR for the study of antioxidants and radical species.


Asunto(s)
Antioxidantes/análisis , Espectroscopía de Resonancia por Spin del Electrón , Radicales Libres/análisis , Animales , Antioxidantes/farmacocinética , Compuestos de Bifenilo/química , Óxidos N-Cíclicos/química , Radicales Libres/metabolismo , Semivida , Humanos , Picratos/química , Detección de Spin
10.
J Med Imaging Radiat Oncol ; 54(2): 134-6, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20518876

RESUMEN

Summary Splenic arteriovenous fistula (SAVF) is a rare but potentially curable condition. Only a few cases have been reported in the English literature. SAVF can cause portal hypertension, ascites, gastrointestinal bleeding, and heart failure. An early diagnosis is essential to avoid life threatening complications. We hereby present a case of SAVF in a young female patient, with hepatitis C liver cirrhosis who presented with recurrent severe upper gastrointestinal bleeding. Such an association of liver cirrhosis and SAVF has not been previously reported.


Asunto(s)
Fístula Arteriovenosa/diagnóstico por imagen , Fístula Arteriovenosa/cirugía , Hepatitis C/diagnóstico por imagen , Hepatitis C/terapia , Hipertensión Portal/diagnóstico por imagen , Hipertensión Portal/terapia , Arteria Esplénica/anomalías , Vena Esplénica/anomalías , Adulto , Fístula Arteriovenosa/complicaciones , Femenino , Hepatitis C/complicaciones , Humanos , Hipertensión Portal/etiología , Radiografía , Arteria Esplénica/diagnóstico por imagen , Arteria Esplénica/cirugía , Vena Esplénica/diagnóstico por imagen , Vena Esplénica/cirugía , Resultado del Tratamiento
11.
Environ Sci Technol ; 43(9): 3365-71, 2009 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-19534159

RESUMEN

The regionalized Global Energy Transition (GET-R 6.0) model has been modified to include a detailed description of light-duty vehicle options and used to investigate the potential impact of carbon capture and storage (CCS) and concentrating solar power (CSP) on cost-effective fuel/vehicle technologies in a carbon-constrained world. Total CO2 emissions were constrained to achieve stabilization at 400-550 ppm, by 2100, at lowesttotal system cost The dominantfuel/vehicle technologies varied significantly depending on CO2 constraint future cost of vehicle technologies, and availability of CCS and CSP. For many cases, no one technology dominated on a global scale. CCS provides relatively inexpensive low-CO2 electricity and heatwhich prolongs the use of traditional ICEVs. CSP displaces fossil fuel derived electricity, prolongs the use of traditional ICEVs, and promotes electrification of passenger vehicles. In all cases considered, CCS and CSP availability had a major impact on the lowest cost fuel/vehicle technologies, and alternative fuels are needed in response to expected dwindling oil and natural gas supply potential by the end of the century.


Asunto(s)
Automóviles , Dióxido de Carbono/química , Fuentes Generadoras de Energía , Gasolina , Transportes , Atmósfera/química , Combustibles Fósiles/economía , Hidrógeno/economía , Energía Solar
12.
Spectrochim Acta A Mol Biomol Spectrosc ; 71(2): 703-9, 2008 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-18394953

RESUMEN

The electron spin resonance (ESR) spectra of free radicals obtained by electrolytic reduction of triazolopyridyl pyridyl ketones and dipyridyl ketones derivatives were measured in dimethylsulfoxide (DMSO). The hyperfine patterns indicate that the spin density delocalization is dependent of the rings presented in the molecule. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO as solvent. When one carbonyl is present in the molecule one step in the reduction mechanism was observed while two carbonyl are present two steps were detected. The first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. The phase-solubility measurements indicated an interaction between molecules selected and cyclodextrins in water. These inclusion complexes are 1:1 with betaCD, and HP-betaCD. The values of Ks showed a different kind of complexes depending on which rings are included. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete agreement with the experimental ones.


Asunto(s)
Compuestos Azo/química , Ciclodextrinas/química , Cetonas/química , Piridinas/química , Electroquímica , Espectroscopía de Resonancia por Spin del Electrón , Estructura Molecular , Solubilidad
13.
Aliment Pharmacol Ther ; 27(11): 1148-55, 2008 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-18331614

RESUMEN

BACKGROUND: Functional dyspepsia is a prevalent condition associated with diminished quality of life (QoL) and high economic burden. AIM: To study the efficacy of a combination of flupenthixol and melitracen (F + M) with anxiolytic and antidepressant properties in functional dyspepsia using a randomized controlled cross-over design. METHODS: Patients met the Rome III criteria for functional dyspepsia and a validated questionnaire was used to exclude those with anxiety or depression. Moreover, patients had to have failed a trial of acid-suppressive therapy and Helicobacter pylori eradication when positive. End points included subjective global symptom relief and QoL assessed by the Nepean Dyspepsia Index (NDI). RESULTS: Twenty-five patients (14 females, 11 males; mean age = 34.3 +/- 9.9 years) were enrolled and 24 completed the 8-week study. There was a significant improvement in subjective global symptom relief with F + M vs. placebo (ITT: 73.9% vs. 26.1%, P = 0.001) and a significant drop in the NDI score vs. placebo (ITT: -9.0 +/- 11.9 vs. -2.4 +/- 8.9, P = 0.03). No difference was noted whether the initial treatment was F + M or placebo. No significant side effects were noted. CONCLUSIONS: A combination of F and M is safe and effective in the short-term treatment of functional dyspepsia. F + M is associated with significant improvement in QoL independent of the presence of anxiety or depression.


Asunto(s)
Antracenos/uso terapéutico , Antipsicóticos/uso terapéutico , Dispepsia/tratamiento farmacológico , Flupentixol/uso terapéutico , Adulto , Estudios Cruzados , Quimioterapia Combinada , Femenino , Humanos , Masculino , Estadística como Asunto
14.
Med Chem ; 4(1): 11-7, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-18220967

RESUMEN

In order to get insight into the trypanocidal mechanism of action of a series of 5-nitrofuryl containing thiosemicarbazones some studies related to their bioreduction were performed. Electron spin resonance spectra of radicals generated in T. cruzi by compounds' bioreduction were analyzed. Three different patterns of ESR signals were observed for the different assayed compounds. These results were in agreement with the changes in the T. cruzi-oxygen uptake promoted by these compounds. On the other hand, free-radical scavenger properties, measured as oxygen radical absorbance capacity (ORAC), did not seem to correlate with the trypanocidal activity.


Asunto(s)
Nitrofuranos/química , Tiosemicarbazonas/síntesis química , Tiosemicarbazonas/farmacología , Tripanocidas/síntesis química , Tripanocidas/farmacología , Animales , Espectroscopía de Resonancia por Spin del Electrón , Depuradores de Radicales Libres/síntesis química , Depuradores de Radicales Libres/química , Depuradores de Radicales Libres/farmacología , Humanos , Oxidación-Reducción/efectos de los fármacos , Consumo de Oxígeno/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Tiosemicarbazonas/química , Tripanocidas/química , Trypanosoma cruzi/efectos de los fármacos , Trypanosoma cruzi/metabolismo
15.
Med Chem ; 2(5): 511-21, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17017991

RESUMEN

The synthesis and evaluation as hypoxic selective cytotoxins of new derivatives of 2-amino or 2-hydroxyphenazine 5,10-dioxide are described. The compounds were developed as structural analogs of other bioreductive compounds and its in vitro cytotoxicities on V79 cells under hypoxic and aerobic conditions were determined. To gain insight into its mechanism of action electrochemical behavior, interaction with DNA experiments and QSAR studies were performed.


Asunto(s)
Citotoxinas/química , Citotoxinas/farmacología , Fenazinas/química , Fenazinas/toxicidad , Relación Estructura-Actividad Cuantitativa , Animales , Hipoxia de la Célula/efectos de los fármacos , Línea Celular , Cricetinae , Citotoxinas/síntesis química , ADN/química , Electroquímica , Estructura Molecular , Fenazinas/síntesis química , Análisis Espectral
16.
Dig Liver Dis ; 38(11): 851-3, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16621745

RESUMEN

Anorectal varices are identified endoscopically in up to 40% of patients with liver cirrhosis [Misra SP, Dwivedi M, Misra V. Prevalence and factors influencing haemorrhoids, anorectal varices, and colopathy in patients with portal hypertension. Endoscopy 1996;28:340-5] but are an infrequent cause of bleeding and their management remains controversial. We present a patient with chronic hepatitis C virus infection who developed recurrent haemorrhage from an isolated, endoscopically inevident rectal varix in the absence of clinical or endoscopic evidence of portal hypertension. The difficulties in diagnosis and management of anorectal varices are highlighted.


Asunto(s)
Endoscopía Gastrointestinal , Hemorragia Gastrointestinal/etiología , Recto/irrigación sanguínea , Várices/diagnóstico , Anciano , Embolización Terapéutica , Hemorragia Gastrointestinal/complicaciones , Hemorragia Gastrointestinal/terapia , Hepatitis C Crónica/complicaciones , Humanos , Masculino , Venas Mesentéricas , Recurrencia , Várices/complicaciones , Várices/terapia
17.
Mini Rev Med Chem ; 6(2): 211-20, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16472188

RESUMEN

Free radicals may be reaction intermediates in biological systems in more situations than are presently recognized. However, progress in detecting such species by Electron Spin Resonance (ESR) has been relatively slow. ESR is a very sensitive technique for free radical detection and characterization. It can be used to investigate very low concentrations of radicals provided that they are stable enough for their presence to be detected. For unstable radicals special techniques have to be employed. One of these methods is called Spin Trapping. Parasitic diseases in tropical and subtropical areas constitute a major health and economic problem. The range of antiparasitic drugs varies widely in structural complexity and action at the subcellular and molecular levels. However, a number of these drugs are thought to exert their action by generating free radicals. Most of the free radical producing drugs used against parasites are: quinones, naphtoquinones, quinone-imines, aminoquinolines, N-oxides and nitroheterocyclic compounds. This review summarizes some of the more relevant achievements of ESR and Spin Trapping applications in parasitic diseases studies. The use of ESR spectroscopy to obtain relevant information about free radical characterization and the analysis of the mechanisms of action of drugs involved in several parasitic diseases is also presented.


Asunto(s)
Antiparasitarios/farmacología , Espectroscopía de Resonancia por Spin del Electrón/métodos , Enfermedades Parasitarias/metabolismo , Marcadores de Spin , Medicina Tropical , Antiparasitarios/uso terapéutico , Humanos , Enfermedades Parasitarias/tratamiento farmacológico
18.
Spectrochim Acta A Mol Biomol Spectrosc ; 61(13-14): 2933-8, 2005 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16165034

RESUMEN

Cyclic voltammetry and electron spin resonance (ESR) techniques were used in the investigation of several potential antiprotozoal thiosemicarbazones nitrofurane derivatives. A self-protonation process involving the protonation of the nitro group due to the presence of an acidic proton in the thiosemicarbazone moiety was observed in the first step of a CEE(rev) reduction mechanism of these derivatives. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. AM1 methodology was used to obtain the optimized geometries and UB3LYP calculations were performed to obtain the theoretical hyperfine coupling constants. The theoretical study exhibited an unusual assignment of the spin densities showing a free radical centered in the thiosemicarbazone moiety rather than the nitro which are in agreement with the experimental hyperfine pattern.


Asunto(s)
Antiprotozoarios/química , Nitrofuranos/química , Tiosemicarbazonas/química , Electroquímica , Espectroscopía de Resonancia por Spin del Electrón , Estructura Molecular , Nitrógeno/química , Oxidación-Reducción
19.
Artículo en Inglés | MEDLINE | ID: mdl-15911420

RESUMEN

The ESR spectra of radicals obtained by electrolytic reduction of 2-acylpyridines and 6,6'-diacyl-2,2'-bipyridines were measured in dimethylsulfoxide (DMSO) and analyzed by quantum chemical calculations. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO solvent. The results showed a two step reduction mechanism, first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete agreement with the experimental ones.


Asunto(s)
Piridinas/química , Acilación , Aniones/química , Dimetilsulfóxido/química , Electroquímica , Electrodos , Espectroscopía de Resonancia por Spin del Electrón , Radicales Libres/química , Estructura Molecular
20.
Pharm Res ; 21(10): 1750-7, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15553218

RESUMEN

PURPOSE: To study the reactivity of C4-substituted 1,4-dihydropyridines (1,4-DHP), with either secondary or tertiary nitrogen in the dihydropyridine ring, toward SIN-1-derived peroxynitrite in aqueous media at pH 7.4. METHODS: Reactivity was followed by changes in the absorptivity of the UV-Vis bands corresponding to 1,4-DHP. Gas Chromatography/ Mass Spectrometer (GC-MS) and Electron Paramagnetic Resonance (EPR) spin trap techniques were used to characterize the final product and the intermediates of the reaction, respectively. RESULTS: 1,4-DHPs significantly reacted toward peroxynitrite at varied rates, according to the calculated kinetic rate constants. By EPR spectroscopy, a carbon-centered radical from the 1,4-DHP was intercepted with N-tert-butylamine-alpha-phenylnitrone (PBN), as the intermediate for the reaction with peroxynitrite. Likewise, the oxidized derivative (i.e., the pyridine) was identified as the final product of the reaction by GC-MS. By using the technique of deuterium kinetic isotope effect, the participation of the hydrogen of the 1-position on the 1,4-DHP ring was shown not to be the rate-limiting step of the reaction. CONCLUSIONS: The direct participation of the 1,4-DHP derivatives in the quenching of SIN-1-derived peroxynitrite has been demonstrated. Kinetic rate constant of tested 1,4-DHP toward peroxynitrite showed a direct relationship with the oxidation peak potential values; that is, compounds reacting faster were more easily oxidized.


Asunto(s)
Dihidropiridinas/química , Molsidomina/análogos & derivados , Molsidomina/química , Ácido Peroxinitroso/química , Deuterio , Espectroscopía de Resonancia por Spin del Electrón , Cromatografía de Gases y Espectrometría de Masas , Indicadores y Reactivos , Cinética , Espectroscopía de Resonancia Magnética , Oxidación-Reducción , Soluciones , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Espectroscopía Infrarroja por Transformada de Fourier
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