Cytoprotective and cytotoxic effects of curcumin: Dual action on H<inf>2</inf>O<inf>2</inf>-induced oxidative cell damage in NG108-15 cells

Abstract

The ability of curcumin, a natural antioxidant isolated from Curcuma longa, to inhibit hydrogen peroxide (H2O2)-induced cell damage in NG108-15 cells was examined. When added simultaneously with 500 μM H2O2, curcumin (25-100 μM) effectively protected cells from oxidative damage. However, when the cells were pretreated with curcumin (25-100 μM) for 1.5 h before H2O2exposure, curcumin was unable to inhibit H2O2-induced cell damage. Instead, it caused a significant concentration-dependent decrease in cell viability after H2O2exposure. This dual action of curcumin suggests that pretreatment with curcumin by itself did not have any significant effect on the viability of the NG108-15 cells, but it sensitized them to oxidative damage induced by H2O2under our experimental conditions. It appears that these events may not relate to the antioxidant and free radical scavenging activities of curcumin.