Astaxanthin, a xanthophyll carotenoid, inhibits ultraviolet‐induced apoptosis in keratinocytes

Intra‐cellular reactive nitrogen/oxygen species and apoptosis play important roles in ultraviolet (UV)‐induced inflammatory responses in the skin. Astaxanthin (AST), a xanthophyll carotenoid, exhibits diverse clinical benefits. The protective effects of AST against UV‐induced apoptosis were investigated in the present study. Astaxanthin (5  μ m ) caused a significant decrease in the protein content and the m RNA levels of inducible nitric oxide (i NOS ) and cyclooxygenase (COX)‐2, and decreased the release of prostaglandin E2 from HaCaT keratinocytes after UVB (20 mJ/cm 2 ) or UVC (5 mJ/cm 2 ) irradiation. No significant protective effects against UV‐induced reactive oxygen species (ROS) were observed in AST‐pretreated cells. Astaxanthin caused a significant inhibition of UV‐irradiation‐induced apoptosis, as evidence by a DNA fragmentation assay. Furthermore, we found that the treatment with AST caused a reduction in the UVB‐ or UVC‐induced protein and m RNA expression of macrophage migration inhibitory factor (MIF), IL‐1 β and TNF‐ α in HaCaT keratinocytes. These results suggest that AST effectively protects against UV‐induced inflammation by decreasing i NOS and COX‐2, and thereby inhibiting the apoptosis of keratinocytes.