N-t-butyl hydroxylamine, a hydrolysis product of alpha-phenyl-N-t-butyl nitrone, is more potent in delaying senescence in human lung fibroblasts.
Alpha-phenyl-N-t-butyl nitrone (PBN), a spin trap, scavenges hydroxyl radicals, protects tissues from oxidative injury, and delays senescence of both normal human lung fibroblasts (IMR90) and senescence-accelerated mice. N-t-butyl hydroxylamine and benzaldehyde are the breakdown products of PBN. N-t-Butyl hydroxylamine delays senescence of IMR90 cells at concentrations as low as 10 microM compared with 200 microM PBN to produce a similar effect, suggesting that N-t-butyl hydroxylamine is the active form of PBN. N-Benzyl hydroxylamine and N-methyl hydroxylamine compounds unrelated to PBN were also effective in delaying senescence, suggesting the active functional group is the N-hydroxylamine. All the N-hydroxylamines tested significantly decreased the endogenous production of oxidants, as measured by the oxidation of 2', 7'-dichlorodihydrofluorescin and the increase in the GSH/GSSG ratio. The acceleration of senescence induced by hydrogen peroxide is reversed by the N-hydroxylamines. DNA damage, as determined by the level of apurinic/apyrimidinic sites, also decreased significantly following treatment with N-hydroxylamines. The N-hydroxylamines appear to be effective through mitochondria; they delay age-dependent changes in mitochondria as measured by accumulation of rhodamine-123, they prevent reduction of cytochrome C(FeIII) by superoxide radical, and they reverse an age-dependent decay of mitochondrial aconitase, suggesting they react with the superoxide radical.
Atamna
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Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA.
Paler-Martínez
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Ames
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D000975:Antioxidants / Q000494:pharmacology*; D016922:Cellular Senescence / Q000187:drug effects*; D003497:Cyclic N-Oxides; D003574:Cytochrome c Group / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006868:Hydrolysis; D006898:Hydroxylamines / Q000494:pharmacology*; D008168:Lung / Q000166:cytology; D008928:Mitochondria / Q000187:drug effects; D009589:Nitrogen Oxides / Q000378:metabolism / Q000494:pharmacology*; D020112:Rhodamine 123 / Q000378:metabolism
D000975:Antioxidants; D003497:Cyclic N-Oxides; D003574:Cytochrome c Group; D006898:Hydroxylamines; D009589:Nitrogen Oxides; D020112:Rhodamine 123; C029217:phenyl-N-tert-butylnitrone; D006861:Hydrogen Peroxide; D005978:Glutathione