Evaluation of the Protection Efficacy of a Sunscreen by Measuring Tissue p53 Levels

Background. the protective efficacy of sunscreens is currently evaluated by the sun protection factor (spf). it is thought that it is not a good indicator of protection against dna damage and that other indicators may prove to be more useful. objective. to study the p53 levels in the skin as a measure of the protective efficacy of sunscreens against ultraviolet light-induced (uv-induced) dna damage. patients and methods. for each of 20 volunteers included in the study, four test areas were specified; 2 treated with broad-spectrum sunscreen formulation with spf 50 and 2 untreated. two minimal erythema doses (meds) of broadband ultraviolet b (uvb) were then applied to one treated and one untreated areas, followed by 3 j/cm2 of ultraviolet a (uva) without photosensitizers. after 48 hours, 3 mm punch biopsies were taken, homogenized, and p53 levels were measured using enzyme linked immuno sorbent assay (elisa) technique.results. p53 levels were significantly higher in irradiated than non-irradiated skin (mean 229.8 ± 76.1 and 91.1 ± 23.6 pg/mg protein, respectively). in addition, p53 levels in irradiated unprotected skin were significantly higher than in irradiated protected skin (mean 229.8 ± 76.1 and 160.7 ± 47.2 pg/mg protein, respectively). conclusion. measurement of p53 in skin homogenates by elisa can be an in vivo assessment tool for the protective efficacy of a sunscreen against uv-induced dna damage