Figure 4.

Effect of ascorbic acid and astaxanthin on H₂O₂-induced oxidative stress model of ARPE-19. The effect of various concentration of ascorbic acid or astaxanthin (pretreated for 6 h and co-treated with H₂O₂ for 24 h) on the response of ARPE-19 cells to sublethal dose of 0.2 mM (A) or lethal dose of 0.4 mM H₂O₂ (B). The cell viability was determined by MTT assay. Treatment of ascorbic acid (500–750 μM) significantly increased ARPE-19 cell viability following 0.2 mM H₂O₂ exposure. However, astaxanthin (10–40 μM) did not significantly affect the cell viability (A). Ascorbic acid (500–750 μM) also significantly increased the cell viability under 0.4 mM H₂O₂ but astaxanthin (10–40 μM) did not have significant effect on the viability (B). Asterisks indicate a significant increment in cell viability compared with cells treated with H₂O₂ only (* p < 0.05, ** p < 0.01). AA, ascorbic acid; AST, astaxanthin; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.