title: Detection of lignin biopolymer- and vitamin E-stimulated reduction of DNA strand breaks in H2O2- and MNNG-treated mammalian cells by the comet assay.
abstract: In this study the possible protective effects of water-soluble sulfur-free lignin biopolymer and vitamin E (alpha-tocopherol) on DNA in human VH10 cells and hamster V79 cells exposed to H2O2 and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated. The level of DNA damage (DNA strand breaks) was measured using single-cell gel electrophoresis, i.e., comet assay. Lignin biopolymer and vitamin E exhibited a protective effect against the overall DNA damage induced after H2O2 treatment. If H2O2-treated human cells were incubated for 90 minutes to ligate frank breaks of DNA, two lesion-specific enzymes, endonuclease III and formamidopyrimidine DNA glycosylase (FPG), significantly increased the level of DNA strand breaks originating from oxidized pyrimidines and purines. Preincubation of cells with lignin or vitamin E reduced mainly the level of oxidized pyrimidines. Reduction of oxidized purines was less evident. In addition, lignin biopolymer exhibited a protective effect against MNNG-induced DNA damage, whereas vitamin E exhibited a protective effect only against H2O2-induced DNA damage. These findings suggest that the antioxidant nature of lignin biopolymer enables a reduction of the level of frank breaks and of oxidized DNA bases in H2O2-treated cells, and its adsorptive capacity enables binding of nitroso compounds and reduction of alkylation in MNNG-treated cells.
authors.affiliation: Department of Mutagenesis and Carcinogenesis, Cancer Research Institute of the Slovak Academy of Sciences, Bratislava, Slovak Republic.
authors.forename: D
authors.initials: D
authors.lastname: Slamenová
authors.forename: E
authors.initials: E
authors.lastname: Horváthová
authors.forename: B
authors.initials: B
authors.lastname: Kosíková
authors.forename: L
authors.initials: L
authors.lastname: Ruzeková
authors.forename: J
authors.initials: J
authors.lastname: Lábaj
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line / Q000187:drug effects; D006224:Cricetinae; D004249:DNA Damage / Q000187:drug effects*; D004586:Electrophoresis; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008031:Lignin / Q000494:pharmacology*; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D016877:Oxidants; D008769:Methylnitronitrosoguanidine; D014810:Vitamin E; D008031:Lignin; D006861:Hydrogen Peroxide