13-hydroperoxylinoleic-acid and 4-oxo-2-nonenal

Analysis of the reaction between 2'-deoxyadenosine and 13-hydroperoxylinoleic acid by liquid chromatography/constant neutral loss mass spectrometry revealed the presence of two major products (adducts A and B). Adduct A was shown to be a mixture of two isomers (A(1) and A(2)) that each decomposed with the loss of water to form adduct B. The mass spectral characteristics of adduct B were consistent with the substituted 1, N(6)-etheno-2'-deoxyadensoine adduct 1' '-[3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-3H-imidazo[2, 1-i]purin-7-yl]heptan-2' '-one. Adducts A(1), A(2), and B were formed when 2'-deoxyadenosine was treated with synthetic 4-oxo-2-nonenal, which suggested that it was formed by the breakdown of 13-hydroperoxylinoleic acid. A substantial increase in the rate of formation of adducts A(1), A(2), and B was observed when 13-hydroperoxylinoleic acid and 2'-deoxyadenosine were incubated in the presence of Fe(II). Thus, 4-oxo-2-nonenal was most likely formed by a homolytic process. Although adducts A(1), A(2), and B were formed in the reaction between 4-hydroxy-2-nonenal and 2'-deoxyadenosine, a number of additional products were observed. This suggested that 4-hydroxy-2-nonenal was not a precursor in the formation of 4-oxo-2-nonenal from 13-hydroperoxylinoleic acid. This study has provided additional evidence which shows that 4-oxo-2-nonenal is a major product of lipid peroxidation and that it reacts efficiently with DNA to form substituted etheno adducts.

Topics: Aldehydes; Animals; Cattle; Chromatography, High Pressure Liquid; Deoxyadenosines; DNA Adducts; Linoleic Acids; Lipid Peroxidation; Mass Spectrometry

Two major products (adducts A and B) from the reaction of 2-deoxyguanosine (dGuo) with 13-hydroperoxylinoleic acid were detected by liquid chromatography/mass spectrometry (LC/MS). Adducts A and B were also the major products formed enzymatically when dGuo was incubated in the presence of linoleic acid and lipoxygenase. The mass spectral fragmentation patterns of adducts A and B suggested that unique modifications to the nucleoside had been introduced. This resulted in the characterization of a novel bifunctional electrophile, 4-oxo-2-nonenal, as the principal breakdown product of linoleic acid hydroperoxide. In subsequent studies, adduct A was found to be a substituted ethano dGuo adduct that was a mixture of three isomers (A(1)-A(3)) that all decomposed to form adduct B. Adduct A(1) was the hemiacetal form of 3-(2-deoxy-beta-D-erythropentafuranosyl)-3,5,6, 7-tetrahydro-6-hydroxy-7-(heptane-2-one)-9H-imidazo[1, 2-alpha]purine-9-one. Adducts A(2) and A(3) were the diastereomers of the open chain ketone form. Adduct B was the substituted etheno dGuo adduct, 3-(2-deoxy-beta-D-erythropentafuranosyl)imidazo-7-(heptane-2 -one)-9-hydroxy[1,2-alpha]purine, the dehydration product of adducts A(1)-A(3). Identical covalent modifications to dGuo were observed when calf-thymus DNA was treated with 4-oxo-2-nonenal. These data illustrate the diversity of reactive electrophiles produced from the peroxidative decomposition of lipids and have implications in fully assessing the role of lipid peroxidation in mutagenesis and carcinogenesis.

Topics: Aldehydes; Animals; Cattle; Chromatography, High Pressure Liquid; Deoxyguanosine; DNA; DNA Adducts; DNA Damage; Linoleic Acids; Lipid Peroxidation; Magnetic Resonance Spectroscopy; Mass Spectrometry