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Evaluation of Sunscreen Protection in Human Melanocytes Exposed to UVA or UVB Irradiation Using the Alkaline Comet Assay ¶
Author(s) -
Jean Séverine,
De Méo Michel,
Sabatier AnneSophie,
Laget Michèle,
Hubaud JeanClaude,
Verrando Patrick,
Duménil Gérard
Publication year - 2001
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2001)0740417eospih2.0.co2
Subject(s) - irradiation , chemistry , comet assay , sun protection factor , photochemistry , microbiology and biotechnology , dna damage , dermatology , physics , biology , medicine , dna , biochemistry , nuclear physics
The in vivo assessment of sunscreen protection does not include the photogenotoxicity of UVA or UVB solar radiation. Using the comet assay we have developed a simple and rapid technique to quantify sunscreen efficacy against DNA damage induced by UV light. Cutaneous human melanocytes from primary cultures were embedded in low‐melting point (LPM) agarose and exposed to UVA (0.8 J/cm 2 ) or to UVB (0.06 J/cm 2 ) through a quartz slide covered with 10 μL volumes of sunscreens. DNA single‐strand breaks induced directly by UVA at 4°C and indirectly through nucleotide excision repair by UVB following a 35 min incubation period at 37°C were quantified using the comet assay. Tail moments (TM) (tail length ×%tail DNA) of 100 cells/sample were determined by image analysis. DNA damage was evaluated with a nonlinear regression analysis on the normalized distribution frequencies of TM using a χ 2 function. The coefficients of genomic protection (CGP) were defined as the percentage of inhibition of DNA lesions caused by the sunscreens. Twenty‐one sunscreens were evaluated, and the calculated CGP were compared with the in vivo sun protective factor (SPF) and with the protection factor UVA (PFA). Nonlinear relationships were found between SPF and CGP UVB and between PFA and CGP UVA .