title: Protective effect of vitamin C towards N-nitrosamine-induced DNA damage in the single-cell gel electrophoresis (SCGE)/HepG2 assay.
abstract: The aim of this study was to investigate the protective effect of vitamin C towards N-nitrosamine-induced DNA damage in the single-cell gel electrophoresis (SCGE)/HepG2 assay. None of the vitamin C concentrations tested (1-10 microM) in presence or absence of formamidopyrimidine-DNA glycosylase (Fpg enzyme) caused DNA damage per se. HepG2 cells simultaneously treated with vitamin C and N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosodibutylamine (NDBA) or N-nitrosopiperidine (NPIP) reduced the genotoxic effects of the N-nitrosamines in a dose-dependent manner. At concentrations of 1-5 microM vitamin C, the protective effect was higher towards NPYR-induced oxidative DNA damage (78-79%) than against NDMA (39-55%), NDBA (12-14%) and NPIP (3-55%), in presence of Fpg enzyme. However, a concentration of 10 microM vitamin C led to a maximum reduction in NDBA (94%), NPYR (81%), NPIP (80%) and NDMA (61%)-induced oxidative DNA damage, in presence of Fpg enzyme. The greatest protective effect of vitamin C (10 microM) was higher towards NDBA-induced oxidative DNA damage. One feasible mechanism by which vitamin C exerted its protective effect is that may interact with the enzyme systems catalyzing the metabolic activation of the N-nitrosamines, blocking the production of genotoxic intermediates. Vitamin C (10 microM) strongly reduced the coumarin hydroxylase (82%) activity. However, the p-nitrophenol hydroxylase and the ethoxyresorufine O-deethylation activities were slightly and weakly reduced (32-19%), respectively.
authors.affiliation: Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Arranz
authors.forename: Ana I
authors.initials: AI
authors.lastname: Haza
authors.forename: Almudena
authors.initials: A
authors.lastname: García
authors.forename: Joseph
authors.initials: J
authors.lastname: Rafter
authors.forename: Paloma
authors.initials: P
authors.lastname: Morales
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000187:drug effects / Q000378:metabolism; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D020552:Comet Assay; D019363:Cytochrome P-450 CYP1A1 / Q000187:drug effects / Q000378:metabolism; D065637:Cytochrome P-450 CYP2A6; D019392:Cytochrome P-450 CYP2E1 / Q000187:drug effects / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D043382:DNA-Formamidopyrimidine Glycosylase / Q000187:drug effects / Q000378:metabolism; D004128:Dimethylnitrosamine / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006899:Mixed Function Oxygenases / Q000187:drug effects / Q000378:metabolism; D009242:N-Nitrosopyrrolidine / Q000633:toxicity; D009602:Nitrosamines / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects
chemical_list: D000975:Antioxidants; D009602:Nitrosamines; C002743:N-nitrosopiperidine; C012279:dibutylnitrosamine; D006899:Mixed Function Oxygenases; D019392:Cytochrome P-450 CYP2E1; D001189:Aryl Hydrocarbon Hydroxylases; D019363:Cytochrome P-450 CYP1A1; D065637:Cytochrome P-450 CYP2A6; D043382:DNA-Formamidopyrimidine Glycosylase; D004128:Dimethylnitrosamine; D001205:Ascorbic Acid; D009242:N-Nitrosopyrrolidine