title: Dual role of vitamin C in an oxygen-sensitive system: discrepancy between DNA damage and cell death.
abstract: Although vitamin C is considered to act both as pro-oxidant and antioxidant, the mechanisms underlying these actions are still unclear. Using the oxygen-sensitive system of a strict anaerobe, Prevotella melaninogenica, we investigated both the pro-oxidant and antioxidant mechanisms of vitamin C. In the presence of vitamin C, the 8-hydroxydeoxyguanosine (8OHdG) formation induced by oxygen exposure was enhanced, probably due to the action of vitamin C on hydrogen peroxide generated during oxygen exposure: while catalase almost completely suppressed the enhancing effect of vitamin C, 8OHdG formation induced by hydrogen peroxide was enhanced by vitamin C. By contrast, the presence of vitamin C inhibited bacterial cell death, membrane damage, and lipid peroxidation induced by oxygen exposure. Sodium azide showed similar effects to vitamin C, thus the antioxidant action of vitamin C may be due to its quenching of the singlet oxygen generated in this system. Both the pro-oxidant and antioxidant effects of vitamin C were observed only in acidic conditions.
authors.affiliation: Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Minyi
authors.initials: M
authors.lastname: Shi
authors.forename: Baohui
authors.initials: B
authors.lastname: Xu
authors.forename: Kazuko
authors.initials: K
authors.lastname: Azakami
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Morikawa
authors.forename: Kunitomo
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kanehisa
authors.initials: K
authors.lastname: Morimoto
authors.forename: Masaharu
authors.initials: M
authors.lastname: Komatsu
authors.forename: Kohji
authors.initials: K
authors.lastname: Aoyama
authors.forename: Toru
authors.initials: T
authors.lastname: Takeuchi
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology*; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation / Q000187:drug effects; D010100:Oxygen / Q000009:adverse effects* / Q000378:metabolism; D001443:Prevotella melaninogenica / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000494:pharmacology; D019810:Sodium Azide / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D000080242:8-Hydroxy-2'-Deoxyguanosine; D019810:Sodium Azide; D006861:Hydrogen Peroxide; D002374:Catalase; D003849:Deoxyguanosine; D001205:Ascorbic Acid; D010100:Oxygen