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1.
Free Radic Res ; 46(1): 11-20, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22023109

RESUMO

Abstract Antioxidant activity of gentisic acid has been studied using fast chemical kinetics and two in vitro models, namely the isolated rat liver mitochondria (RLM) and the human erythrocytes. The presence of gentisic acid (GA) during irradiation significantly reduced the levels of gamma radiation induced damages to lipids and proteins in RLM. Further, GA imparted protection to the human erythrocytes against exposure to gamma radiation. Molecular mechanism of free radical scavenging reactions has been evaluated with the help of rate constants and transients obtained from gentisic acid using pulse radiolysis technique. GA efficiently scavenged hydroxyl radical (k = 1.1 × 10(10) dm(3)mol(-1)s(-1)) to produce reducing adduct radical (~76%) and oxidizing phenoxyl radical (~24%). GA has also scavenged organohaloperoxyl radical (k = 9.3 × 10(7) dm(3) mol(-1)s(-1)). Ascorbate has been found to repair phenoxyl radical of GA (k = 1.0 × 10(7) dm(3)mol(-1)s(-1)). Redox potential value of GA(•)/GA couple (0.774 V vs NHE) obtained by cyclic voltammetry is less than those of physiologically important oxidants, which supports the observed antioxidant capacity of GA. We, therefore, propose that the antioxidant and radioprotective properties of GA are exerted by its phenoxyl group.


Assuntos
Antioxidantes/farmacologia , Sequestradores de Radicais Livres/farmacologia , Gentisatos/farmacologia , Animais , Antioxidantes/química , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Feminino , Sequestradores de Radicais Livres/química , Gentisatos/química , Humanos , Radical Hidroxila/metabolismo , Cinética , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Oxirredução , Fenóis/química , Fenóis/metabolismo , Radiólise de Impulso , Ratos , Ratos Wistar
2.
Bioorg Med Chem ; 14(18): 6414-9, 2006 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-16766192

RESUMO

A novel conjugate of melatonin 2 and alpha-lipoic acid 4 has been prepared using DCC mediated coupling. The conjugate named melatoninolipoamide has been assigned its structure 1 on the basis of spectral analysis (UV, IR, NMR, and EI-MS). Pulse radiolysis studies of the conjugate were carried out in aqueous solutions with both oxidizing and reducing radicals. The results indicate that the melatonin moiety of the conjugate reacts preferably with oxidizing radicals and the lipoic acid moiety exhibits preferential reaction with reducing radicals. The in vitro radioprotection ability of 1 was examined by gamma-radiation induced lipid peroxidation in liposomes and hemolysis of erythrocytes, and compared the results with those of melatonin and alpha-lipoic acid. The studies suggest that the conjugate can be explored as a probable radioprotector.


Assuntos
Melatonina/análogos & derivados , Melatonina/química , Protetores contra Radiação/síntese química , Ácido Tióctico/análogos & derivados , Ácido Tióctico/química , Radicais Livres/química , Melatonina/síntese química , Estrutura Molecular , Oxirredução , Radiólise de Impulso/métodos , Protetores contra Radiação/química , Ácido Tióctico/síntese química
3.
Phytomedicine ; 11(6): 530-8, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15500265

RESUMO

Aqueous extract of a natural herb, Terminalia chebula was tested for potential antioxidant activity by examining its ability to inhibit gamma-radiation-induced lipid peroxidation in rat liver microsomes and damage to superoxide dismutase enzyme in rat liver mitochondria. The antimutagenic activity of the extract has been examined by following the inhibition of gamma-radiation-induced strand breaks formation in plasmid pBR322 DNA. In order to understand the phytochemicals responsible for this, HPLC analysis of the extract was carried out, which showed the presence of compounds such as ascorbate, gallic acid and ellagic acid. This was also confirmed by cyclic voltammetry. The extract inhibits xanthine/xanthine oxidase activity and is also an excellent scavenger of DPPH radicals. The rate at which the extract and its constituents scavenge the DPPH radical was studied by using stopped-flow kinetic spectrometer. Based on all these results it is concluded that the aqueous extract of T. chebula acts as a potent antioxidant and since it is able to protect cellular organelles from the radiation-induced damage, it may be considered as a probable radioprotector.


Assuntos
Antioxidantes/farmacologia , Fitoterapia , Extratos Vegetais/farmacologia , Lesões por Radiação/prevenção & controle , Protetores contra Radiação/farmacologia , Terminalia , Animais , Antioxidantes/administração & dosagem , Antioxidantes/uso terapêutico , Compostos de Bifenilo , Relação Dose-Resposta a Droga , Frutas , Raios gama/efeitos adversos , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/efeitos da radiação , Mitocôndrias Hepáticas/efeitos dos fármacos , Picratos/química , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Protetores contra Radiação/administração & dosagem , Protetores contra Radiação/uso terapêutico , Ratos , Ratos Wistar
4.
Neurosci Res ; 22(1): 117-22, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7792076

RESUMO

In this study we examined the effects of rapid eye movement sleep (REMS) deprivation on synaptosomal and microsomal membrane fluidity by studying 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence polarization in control as well as REMS-deprived rats. The flower pot technique was used to perform 24, 48 and 96 h REMS deprivation. Suitable control experiments were carried out to rule out the nonspecific effects. The results showed that DPH fluorescence polarization increased both in the microsome as well as in the synaptosome in REMS-deprived animals, except in the cerebellum, indicating that there was a generalized decrease in membrane fluidity in the rat brain. The alterations in membrane fluidity returned to baseline upon recovery from REMS deprivation. Control experiments suggested that the alterations were primarily caused by REMS deprivation and not due to nonspecific effects. This finding supports REMS deprivation induced other changes reported earlier. This increase in membrane rigidity could be at least one of the possibilities for REMS loss induced alterations in physiological phenomena including membrane bound enzyme activities and receptor densities.


Assuntos
Encéfalo/fisiologia , Fluidez de Membrana/fisiologia , Privação do Sono/fisiologia , Sono REM/fisiologia , Animais , Axônios/fisiologia , Membrana Celular/fisiologia , Polarização de Fluorescência , Masculino , Microssomos/fisiologia , Ratos , Ratos Wistar , Sinaptossomos/fisiologia
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