Mariko Sugiyama, Masaaki Mori, Masatoshi Hoya, Morihiko Hirota and Hiroshi Itagaki
Original paper :AATEX 9(1):29-39
Many in vitro methods to predict phototoxicity, based on various mechanisms, have been developed and reported. We have evaluated 3 types of in vitro methods and used this battery of assays to assess the phototoxicity of cosmetic ingredients. The in vitro methods used were photohemolysis testing of red blood cells (RBC), a technique to predict damage to cellular membranes, yeast growth inhibition assay, and the 3T3 mouse fibroblast neutral red uptake phototoxicity test (3T3 NRU PT), a candidate for the OECD guideline procedure to estimate phototoxic effects on cell organelles.
In comparison with in vivo data in guinea pigs, the yeast growth inhibition assay was the most highly correlated method. No false negatives were observed in the battery system of yeast growth inhibition assay and RBC photohemolysis assay. Because only a few chemicals gave positive reactions in the RBC photohemolysis or 3T3 NRU PT assay, it was suggested that a combination of methods based on different mechanisms would be needed for the safety assessment of phototoxicity of chemicals. Our results indicated that the battery system of the yeast growth inhibition assay and RBC photohemolysis assay is the most effective tool for assessing the phototoxicity of cosmetic ingredients. It is also important to select methods compatible with the physicochemical properties of the chemicals to be tested.
Key words: phototoxicity, in vitro test, battery system, yeast growth inhibition assay, photohemolysis