**5. Conclusions**

In summary, the antioxidative e ffect of ascorbic acid and astaxanthin was evaluated in this study using two di fferent oxidative stress models achieved by H2O2 and UVB. Despite controversies questioning the antioxidative property of ascorbic acid, it was shown in this study that ascorbic acid diminishes the oxidative damage within human RPE oxidative stress models of H2O2 and UVB which reflect general circumstance of oxidatively stressed environment. This study also showed the ROS scavenging capacity of astaxanthin in a UVB-induced stress model. Synergistic e ffect of ascorbic acid and astaxanthin was also shown resulting in increment in cell viability and reduction in intracellular ROS level.

**Author Contributions:** S.O. performed the experiment and wrote the manuscript; Y.J.K. performed the experiment; E.K.L. reviewed, wrote, and edited the manuscript; S.W.P. designed the experiment; H.G.Y. designed all experiments and reviewed the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by a gran<sup>t</sup> of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI14C1277).

**Conflicts of Interest:** The authors declare no conflict of interest.
