Direct determination of diene conjugation and deoxyribonucleic acid (DNA) oxidative damage can explain the role of DTPA-Fe(2+)-O2 complex in a linoleic acid-DNA system.

Abstract

Exposure of linoleic acid to diethylenetriminepentaacetic acid (DTPA)-Fe(2+) complexes resulted in fast diene conjugation and peroxidized products which could further react with deoxyribonucleic acid (DNA) to cause DNA oxidative damage. In this paper, we have detected diene conjugation and DNA oxidative damage in a linoleic acid-DNA model system driven by DTPA-Fe(2+) and found that: 1. in air or oxygen-saturated reaction systems, addition of hydrogen peroxide resulted in a decrease in diene conjugation and double-stranded DNA content, but had no obvious effects on the formation of DNA fluorescent products; 2. in anoxic conditions, addition of hydrogen peroxide had no effect on the formation of diene conjugation and fluorescent products, but resulted in a decrease of double-stranded DNA content; 3. in the presence of DTPA, Fe(3+) did not stimulate the formation of diene conjugation; 4. the formation of diene conjugation and fluorescent products was not inhibited by superoxide dismutase, catalase, sodium benzoate, sodium azide and mannitol. However, these 'scavengers' increased the percentage of double-strand DNA to different degrees. α-tocopherol, but not reduced glutathione (GSH), inhibited the formation of diene conjugates. α-tocopherol and GSH both could reduce the amounts of fluorescent products and DNA strand breaks. Taken together, these data further indicate that chelator-Fe(2+)-O2 complex, a perferryl-type oxidant, is probably an important initiator of lipid peroxidation in the linoleic acid-DNA system.