Prooxidant action of two antioxidants: ascorbic acid and gallic acid.

The addition of two antioxidants, ascorbic acid or gallic acid to distilled water resulted in the rapid increase in the reduction potential, which a few seconds later was replaced with much higher oxidation potential. The addition of these compounds to culture medium dose-dependently increased the oxidation potential only. Ascorbic acid analogs, which had apoptosis-inducing activity, showed similar oxidation potential, whereas inactive analogs did not. The combination of ascorbate and hydrogen peroxide additively enhanced both the oxidation potential and cytotoxic activity. These data demonstrate that both ascorbic acid and gallic acid act as prooxidants for the induction of apoptotic cell death.