Protection from solar simulated radiation-induced DNA damage in cultured human fibroblasts by three commercially available sunscreens

Exposure to solar radiation can produce both acute and chronic changes in the skin, including sunburn, edema, immunosuppression, premature skin aging, and skin cancer. At the cellular level, solar radiation can produce adverse structural and functional changes in membrane proteins and lipids and in chromosomal and mitochondrial DNA. The increasing awareness of these adverse effects has led the public to demand better photoprotection. In this study, the alkaline comet assay was used to evaluate the photoprotective effects of three commercially available sunscreens at sun protection factors (SPF) 15 and 30. Human fibroblasts were used as target cells to conveniently study the effects of solar simulated radiation on DNA damage in the presence and absence of sunscreens. When human fibroblasts were exposed to various doses of solar simulated radiation, DNA damage, as measured in sunscreen-protected cells by the comet assay, was not significantly different from that detected in unexposed cells. At 1.0 and 1.5 minimal erythemal doses (MED), all sunscreens, at both SPF 15 and 30, provided nearly 100% photoprotection to the fibroblasts. Further studies are required to elucidate the role of UVA in the production and repair of DNA damage in cells exposed to sunlight.