Figure 7.

Intracellular ROS level and cell viability of ARPE-19 after H₂O₂ exposure with ascorbic acid and the mixture of ascorbic acid and astaxanthin. Ascorbic acid at 500 μM significantly reduced the intracellular ROS level under sublethal and lethal dose of H₂O₂ (0.2–0.4 mM) compared to the control group without ascorbic acid treatment (A). The effect of 20 μM astaxanthin, 90 μM ascorbic acid, and the mixture of the two compounds on the cell viability of ARPE-19 under H₂O₂-induced oxidative stress was examined by MTT assay. Cell viability was significantly increased when the cells were pretreated with 20 μM astaxanthin, 90 μM ascorbic acid, and the mixture of the two compounds for 6 h and with 0.2 mM H₂O₂ for 24 h, compared to H₂O₂ only (B). ROS level was significantly decreased when the cells were pretreated with 20 μM astaxanthin, 90 μM ascorbic acid, and the mixture of the two compounds for 6 h and with 0.2 mM H₂O₂ for 24 h, compared to H₂O₂ only. Asterisks indicate a significant difference between increment in cell viability and reduction in intracellular ROS level compared to control cells only with H₂O₂ exposure without antioxidant treatment (C). (** p < 0.01, *** p < 0.001). AST, astaxanthin; AA, ascorbic acid; ROS, reactive oxygen species; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.