Vitamin C Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin C, including details on benefits, dosage, supplements, information.

Dual role of vitamin C in an oxygen-sensitive system: discrepancy between DNA damage and cell death.

Shi M, Xu B, Azakami K, Morikawa T, Watanabe K, Morimoto K, Komatsu M, Aoyama K, Takeuchi T

Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.

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.

Published 14 March 2005 in Free Radic Res, 39(2): 213-20.
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