8. In vitro studies on DNA damage due to mixtures of ascorbate and iron(II)

Mariam Farhad, Fazlul Huq^* and Ponnanbalam Sivanandasingham

School of Biomedical Sciences, Faculty of Health Sciences, The University of Sydney,  Australia, E-mail : f.huq@fhs.usyd.edu.au

(Received 09 November 2005; accepted 27 December 2005)

 Abstract: Damage to salmon sperm and pBR322 plasmid DNAs due to mixtures of iron(II) ammonium sulfate and ascorbate (AA) at pH 7.6 in air is found to be much greater than that due to either Fe²⁺ or AA alone. At any given concentration of Fe²⁺, DNA damage generally increases with increase in concentration of AA. The results illustrate that in in vitro situations in presence of Fe²⁺, AA acts only as a pro-oxidant so that excess AA does not provide any protective role against DNA damage. Although the current in vivo results appear to be conflicting, the results of the present in vitro experiment call for more well-designed in vivo experiments. Because, if the results of the present in vitro experiments were applicable to in vivo situations, one would conclude that there would be a danger of DNA damage from co-supplementation of iron and AA. Biological systems are however complex and complicated by the presence of many other antioxidants and concurrent reactions.

Key words: Ascorbate, iron, ROS, DNA damage

<<<