RESUMO
It was found that methyl green, a major groove binding ligand and the minor groove binding ligands, netropsin and 2,7-di-tert-butylproflavine inhibit, to a similar extend a monoadduct forming benzopsoralen and monoadduct and diadduct forming derivatives of psoralen (8-methoxypsoralen and 3,4'-dimethyl-8-methoxypsoralen). Caffeine exhibits an inhibitory effect on furocoumarin photobinding to DNA at 10(3) fold higher concentration. Together with the previously published results it is concluded that both occupancy of the major and minor groove as well as intercalation hinder photobinding of furocoumarins to DNA.
Assuntos
DNA/química , Metoxaleno/análogos & derivados , Metoxaleno/química , Verde de Metila/química , Netropsina/química , Proflavina/análogos & derivados , Animais , Cafeína/química , Bovinos , Metoxaleno/antagonistas & inibidores , Fotoquímica , Proflavina/químicaRESUMO
The treatment of human lymphocytes in vitro with 5-methoxypsoralen (5-MOP) plus UV-A induces a dose-dependent increase in the SCE rate and in structural chromosome aberrations. We carried out tests to see whether the clastogenic effect of 5-MOP plus UV-A could be reduced by the anticlastogen beta-aminoethylisothiouronium (AET). The occurrence of a protective effect proved to be dependent upon the conditions of treatment. When AET was present over a long period of time (22 h) in cultures with 5-MOP, the number of breaks was reduced compared with such cultures without AET (reduction factor 0.5-0.6). On the other hand, a short period of action by AET (1.5 h) in the presence of 5-MOP produced no reduction of breaks. Posttreatment with AET (20 h) yielded an obvious protective effect (reduction factor 0.2-0.4). The possible mechanisms of the protective effect of AET are discussed.
Assuntos
Aberrações Cromossômicas/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Metoxaleno/efeitos adversos , Mutagênicos , beta-Aminoetil Isotioureia/farmacologia , 5-Metoxipsoraleno , Aberrações Cromossômicas/efeitos da radiação , Humanos , Linfócitos/ultraestrutura , Metoxaleno/antagonistas & inibidores , Testes de Mutagenicidade , Troca de Cromátide Irmã/efeitos dos fármacos , Troca de Cromátide Irmã/efeitos da radiação , Raios UltravioletaRESUMO
Influence of antioxidants on two phototoxic effects of 8-methoxypsoralen (8-MOP) was studied: erythema and changes in mechanoelectrical properties of skin. alpha-Tocopherol and its analogs with shortened lateral hydrocarbon chains at C2-atoms of chromane groups (chromanols) were used as antioxidants. alpha-Tocopherol and its analogs inhibited both phototoxic effects of 8-MOP. Inhibition was observed only if antioxidants were present in skin during irradiation. When applied after irradiation these antioxidants produce no inhibitory effect. The antioxidant antierythemal action depends greatly on their concentration. The protective effects is maximal at antioxidant concentrations 2.5 . 10(-10) - 5 . 10(-9) mol . cm-2 of skin, at concentrations higher than 5 . 10(-9) mol . cm-2 the protective action is decreased. The protective effect of antioxidants depends on the irradiation dose.
Assuntos
Antioxidantes/farmacologia , Eritema/etiologia , Terapia PUVA/efeitos adversos , Fotoquimioterapia/efeitos adversos , Pele/efeitos dos fármacos , Vitamina E/farmacologia , Animais , Eritema/prevenção & controle , Resposta Galvânica da Pele , Humanos , Metoxaleno/antagonistas & inibidores , Coelhos , Pele/fisiopatologia , Pele/efeitos da radiação , Vitamina E/análogos & derivadosRESUMO
Irradiation of the rabbit and human skin by near UV light (wave lengths greater than 320 nm) in the presence of 8-methoxypsoralen produced erythema, pigmentation and some changes in the mechanical and electric properties. All the photobiological effects mentioned were inhibited by alpha-tocopherol if it was applied before irradiation. When applied after exposure to irradiation alpha-tocopherol appeared to be ineffective.
