title: Assessment of the photoprotection properties of sunscreens by chromatographic measurement of DNA damage in skin explants.
abstract: Evaluation of the photoprotection provided by sunscreens is performed either through the induction of erythema and expressed as the sun protection factor (SPF), or by the UVA-mediated persistent pigment darkening (PPD). None of these two endpoints has a link with skin cancer, the most deleterious consequence of excess exposure to solar UV radiation. We thus set up a complementary approach to evaluate the protection provided by sunscreens to the genome of human skin. This is based on the quantification of the thymine cyclobutane dimer (TT-CPD), the main DNA lesion induced by both UVB and UVA radiations. Irradiations were performed ex vivo on human skin explants and the level of TT-CPD in DNA was determined by HPLC associated with tandem mass spectrometry. The technique was first optimized and validated with three standard sunscreens. The study was then extended to the evaluation of a commercial high SPF sunscreen exhibiting efficient UVA photoprotection. The DNA protecting factor was found to reflect the ratio between UVB and UVA photoprotection, although the absolute values of the genomic protection were, as a general trend, lower than either SPF or PPD. These data show the usefulness of the proposed approach for the evaluation of the genoprotection afforded by sunscreens.
authors.affiliation: CEA, INAC, SCIB, UJF & CNRS, LCIB (UMR_E 3 CEA-UJF and FRE 3200), Laboratoire Lésions des Acides Nucléiques, Grenoble Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Mouret
authors.forename: Patrick
authors.initials: P
authors.lastname: Bogdanowicz
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Haure
authors.forename: Nathalie
authors.initials: N
authors.lastname: Castex-Rizzi
authors.forename: Jean
authors.initials: J
authors.lastname: Cadet
authors.forename: Alain
authors.initials: A
authors.lastname: Favier
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004249:DNA Damage; D006801:Humans; D066298:In Vitro Techniques; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D013473:Sunscreening Agents; D053719:Tandem Mass Spectrometry
chemical_list: D013473:Sunscreening Agents