Synergistic lethal effect between hydrogen peroxide and neocuproine (2,9-dimethyl 1,10-phenanthroline) in Escherichia coli.
Despite 2,9-dimethyl 1,10-phenanthroline (NC) has been extensively used as a potential inhibitor of damage due to oxidative stress in biological systems, the incubation of E. coli cultures with the copper ion chelator NC prior to the challenge with hydrogen peroxide caused a lethal synergistic effect. The SOS response seems to be involved in the repair of the synergistic lesions through the recombination pathway. Furthermore, there is evidence for the UvrABC excinuclease participation in the repair of the synergistic lesions, and the base excision repair may also be required for bacterial survival to the synergistic effect mainly at high concentrations of H2O2, being the action of Fpg protein an important event. Incubation of lexA (Ind-) cultures with iron (II) ion chelator 2,2'-dipyridyl simultaneously with NC prevented the lethal synergistic effect. This result suggests an important role of the Fenton reaction on the phenomenon. NC treatment was able to increase the number of DNA strand breaks (DNAsb) induced by 10 mM of H2O2 in lexA (Ind-) strain and the simultaneous treatment with 2,2'-dipyridyl was able to block this effect.
Laboratório de Radiobiologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Bloco G, Universidade Federal do Rio de Janeiro, Brazil.
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Almeida
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Felício
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Galhardo
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JB
Cabral-Neto
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Leitão
D015082:2,2'-Dipyridyl / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002499:Centrifugation, Density Gradient; D002614:Chelating Agents / Q000378:metabolism; D004247:DNA / Q000032:analysis; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology / Q000633:toxicity; D007501:Iron / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D010618:Phenanthrolines / Q000378:metabolism / Q000633:toxicity; D011995:Recombination, Genetic / Q000235:genetics; D013014:SOS Response, Genetics / Q000235:genetics
D001426:Bacterial Proteins; D002614:Chelating Agents; C045076:Fenton's reagent; D010618:Phenanthrolines; D015082:2,2'-Dipyridyl; C002701:neocuproine; D004247:DNA; D006861:Hydrogen Peroxide; D007501:Iron