title: AFMK, a melatonin metabolite, attenuates X-ray-induced oxidative damage to DNA, proteins and lipids in mice.
abstract: Antioxidant function of melatonin is well established. However, N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK), a melatonin metabolite is a sparingly investigated biogenic amine, especially in relation to its in vivo antioxidant function. We have evaluated the oxidative damage to biomolecules (DNA, protein and lipid) induced by X-irradiation in C57BL mice and the prophylactic action of AFMK. The extent of DNA damage was analyzed by single-cell gel electrophoresis in cerebral cortex and serum 8-hydroxydeoxyguanosine (8-OHdG) levels by enzyme-linked immunosorbent assay. Oxidative modification of protein and lipid was measured in the terms of carbonyl content and 4-HAE + MDA (4-hydroxyalkenal + malondialdehyde) status of brain cortex. Radiation exposure dramatically augmented the level of 8-OHdG in serum as well as DNA migration in the comet tail. AFMK pretreatment significantly inhibited DNA damage. In addition, radiation-induced augmentation of protein carbonyl content and HAE + MDA was ameliorated by AFMK pretreatment. Whole-body exposure of mice to X-irradiation also reduced the level of brain sulfhydryl contents (protein-bound sulfhydryl, total sulfhydryl, and nonprotein sulfhydryl) which were significantly protected by AFMK. Radiation-induced decline in the total antioxidant capacity of plasma was significantly reversed in AFMK pretreated mice. Moreover, AFMK showed a very high level of in vitro hydroxyl radical scavenging potential which was measured by an electron spin resonance (ESR) study of the 2-hydroxy-5,5-dimethyl-1-pyrrolineN-oxide (DMPO-OH) adduct. IC(50) values resulting from ESR analysis was 338.08 nm. The present study indicate that AFMK is a potent antioxidant in both in vivo and in vitro systems.
authors: National Institute of Radiological Science, Chiba, Japan.
authors: Kailash
authors: K
authors: Manda
authors: Megumi
authors: M
authors: Ueno
authors: Kazunori
authors: K
authors: Anzai
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D020552:Comet Assay; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage / Q000187:drug effects*; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D007735:Kynuramine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000528:radiation effects*; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000187:drug effects* / Q000528:radiation effects; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D014965:X-Rays
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D009419:Nerve Tissue Proteins; D007735:Kynuramine; C041550:N-acetyl-N-formyl-5-methoxykynurenamine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; D003849:Deoxyguanosine; D008550:Melatonin