scholarly journals Effect of Plant Phenolics on the Formation of the Spin-Adduct of Hydroxyl Radical and the DNA Strand Breaking by Hydroxyl Radical.

1996 ◽  
Vol 19 (4) ◽  
pp. 558-563 ◽  
Author(s):  
Kazuyuki HIRAMOTO ◽  
Natsuko OJIMA ◽  
Ken-ichi SAKO ◽  
Kiyomi KIKUGAWA
Keyword(s):  
Hydroxyl Radical ◽  
Spin Adduct ◽  
Plant Phenolics ◽  
Dna Strand

scholarly journals DNA Strand Damage Product Analysis Provides Evidence That the Tumor Cell-Specific Cytotoxin Tirapazamine Produces Hydroxyl Radical and Acts as a Surrogate for O2

2007 ◽  
Vol 129 (42) ◽  
pp. 12870-12877 ◽  
Author(s):  
Goutam Chowdhury ◽  
Venkatraman Junnotula ◽  
J. Scott Daniels ◽  
Marc M. Greenberg ◽  
Kent S. Gates
Keyword(s):  
Tumor Cell ◽  
Hydroxyl Radical ◽  
Product Analysis ◽  
Dna Strand

Binding affinity of Cu(II)–VP-16 (etoposide) complex and its analogues to DNA and hydroxyl radical generation During DNA strand breaks

1998 ◽  
Vol 6 (7) ◽  
pp. 1003-1008 ◽  
Author(s):  
Riichi Tawa ◽  
Dayuan Gao ◽  
Masashi Takami ◽  
Yasuhiro Imakura ◽  
Kuo-Hsiung Lee ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Binding Affinity ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
Radical Generation ◽  
Dna Strand

scholarly journals Endogenous Superoxide Dismutase Levels Regulate Iron-Dependent Hydroxyl Radical Formation in Escherichia coli Exposed to Hydrogen Peroxide

1998 ◽  
Vol 180 (3) ◽  
pp. 622-625 ◽  
Author(s):  
Michael L. McCormick ◽  
Garry R. Buettner ◽  
Bradley E. Britigan
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Superoxide Dismutase ◽  
Hydroxyl Radical ◽  
Iron Chelator ◽  
Spin Adduct ◽  
Control Strain ◽  
Paramagnetic Resonance ◽  
Fenton Chemistry ◽  
E Coli

ABSTRACT Aerobic organisms contain antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, to protect them from both direct and indirect effects of reactive oxygen species, such as O2 ·− and H2O2. Previous work by others has shown that Escherichia colimutants lacking SOD not only are more susceptible to DNA damage and killing by H2O2 but also contain larger pools of intracellular free iron. The present study investigated if SOD-deficient E. coli cells are exposed to increased levels of hydroxyl radical (·OH) as a consequence of the reaction of H2O2 with this increased iron pool. When the parental E. coli strain AB1157 was exposed to H2O2 in the presence of an α-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (4-POBN)–ethanol spin-trapping system, the 4-POBN–·CH(CH3)OH spin adduct was detectable by electron paramagnetic resonance (EPR) spectroscopy, indicating ·OH production. When the isogenic E. coli mutant JI132, lacking both Fe- and Mn-containing SODs, was exposed to H2O2 in a similar manner, the magnitude of ·OH spin trapped was significantly greater than with the control strain. Preincubation of the bacteria with the iron chelator deferoxamine markedly inhibited the magnitude of·OH spin trapped. Exogenous SOD failed to inhibit·OH formation, indicating the need for intracellular SOD. Redox-active iron, defined as EPR-detectable ascorbyl radical, was greater in the SOD-deficient strain than in the control strain. These studies (i) extend recent data from others demonstrating increased levels of iron in E. coli SOD mutants and (ii) support the hypothesis that a resulting increase in ·OH formation generated by Fenton chemistry is responsible for the observed enhancement of DNA damage and the increased susceptibility to H2O2-mediated killing seen in these mutants lacking SOD.

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