Protective Effects of Oral Astaxanthin Nanopowder against Ultraviolet‐Induced Photokeratitis in Mice

Purpose . Astaxanthin (AST) has a strong antioxidant cellular membrane chaperone protective effect. Recently, a water‐soluble nanosized AST (nano‐AST) form was produced, which is expected to improve the efficacy of oral intake effects. The purpose of this study was to examine whether oral nano‐AST has therapeutic effects on UV‐induced photokeratitis in mice. Methods . C57BL/6 mice were administered twice with either nano‐AST, AST oil, lutein, or bilberry extracts 3 hours before and shortly before UV irradiation (dose: 400 mJ/cm 2 ). The corneas were collected 24 hours after irradiation and stained with H&E and TUNEL. NF‐ κ B, dihydroethidium (DHE), COX‐2, p‐I κ B‐ α , TNF α , and CD45 expression were evaluated through immunohistochemistry, Western blot analysis, and qPCR. Results . Corneal epithelium was significantly thicker in mice orally administered with nano‐AST than in the others ( p < 0.01), with significantly less NF‐ κ B nucleus translocation ( p < 0.001), and significantly fewer TUNEL cells ( p < 0.01). Weaker DHE signals were detected in the nano‐AST group ( p < 0.05) relative to the others. Furthermore, reduced inflammation and decreased cell death in corneal tissue were observed in the nano‐AST group, as indicated by a reduction in the expression of COX‐2, p‐I κ B‐ α , TNF α , and CD45. Conclusions . Oral administration of nano‐AST demonstrated a protective effect on UV‐induced photokeratitis via antioxidative, anti‐inflammatory, and antiapoptotic activity.