title: Mechanism of oxidative DNA damage induced by delta-aminolevulinic acid in the presence of copper ion.
abstract: Delta-Aminolevulinic acid (ALA) is a heme precursor accumulated in lead poisoning and acute intermittent porphyria. ALA-induced DNA damage in the presence of metal ions was investigated with a DNA sequencing technique and a high-performance liquid chromatograph equipped with an electrochemical detector. ALA caused damage to DNA fragments obtained from c-Ha-ras proto-oncogene in the presence of Cu(II), but only slightly in the presence of Fe(II). ALA + Cu(II) induced piperidine-labile sites at thymine residues, especially in the 5'-GTC-3' and 5'-CTG-3' sequences of double-stranded DNA. Catalase and bathocuproine inhibited DNA damage induced by ALA + Cu(II). Typical .OH scavengers did not inhibit DNA damage, suggesting that active species other than .OH play a more important role in DNA damage. 8-Hydroxy-2'-deoxyguanosine formation by ALA increased with ALA concentration in the presence of Cu(II). Electron spin resonance studies using alpha-(1-oxy-4-pyridyl)-N-tert-butylnitrone as spin trap showed that carbon-centered radicals were generated during Cu(II)-catalyzed autoxidation of ALA. The major pathway of ALA autoxidation consists for the formation of 4,5-dioxovaleric acid and NH(4)+. Formation of a pyrazine derivative through ALA autocondensation was also observed. Concomitantly, O2- and H2O2 were generated during the Cu(II)-catalyzed ALA autoxidation. These results indicate that H2O2 reacts with Cu(I) to form a crypto-OH radical, such as the Cu(I)-peroxide complex, causing DNA damage. The possible mechanism for metal-dependent DNA damage by ALA is discussed in relation to the carcinogenicity of lead compounds and the increased frequency of liver cancer in acute intermittent porphyria.
authors.affiliation: Department of Public Health, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hiraku
authors.forename: S
authors.initials: S
authors.lastname: Kawanishi
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000622:Aminolevulinic Acid / Q000633:toxicity; D001483:Base Sequence; D002374:Catalase / Q000494:pharmacology; D003300:Copper / Q000633:toxicity; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000494:pharmacology; D011905:Genes, ras / Q000187:drug effects; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000494:pharmacology; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: D016166:Free Radical Scavengers; D009838:Oligodeoxyribonucleotides; D010618:Phenanthrolines; D017665:Hydroxyl Radical; D003300:Copper; D000622:Aminolevulinic Acid; D000080242:8-Hydroxy-2'-Deoxyguanosine; C002478:bathocuproine; D002374:Catalase; D003849:Deoxyguanosine