Routaboul Corinne, Denis Alain, Bohbot Michel
Bioderma, 75, cours A.-Thomas, 69447 Lyon Cedex 3, France.
Eur J Dermatol. 2002 Sep-Oct;12(5):439-44.
In order to define a new method for measuring UVA photoprotection, we built an in vitro immediate pigment darkening model (IPD). IPD is a photochemical reversible reaction induced by UVA on the skin. Our model consists of aqueous solutions of melanocytic compounds (dihydroxyphenylalanine/pheomelanins). Irradiation of these solutions with UVA induces an increase in their absorbance. Oxygen deprivation inhibits the solution darkening and light turn-off induces a decrease in the absorbance as observed in vivo. A UVA photoprotection parameter (PUVA) was defined using the ability of a sunscreen to inhibit the model reaction. A calibration of the reaction inhibition is realised using neutral beam attenuators. PUVA is defined as the percentage absorbance of a beam attenuator which would have the same inhibitory effect as the sunscreen tested. A correlation between PUVA and Diffey-Robson parameter is presented. The method developed here could be use as a indicative tool before human experiments.
为了定义一种测量UVA光防护的新方法，我们构建了一个体外即时色素沉着模型（IPD）。IPD是UVA在皮肤上诱导的一种光化学可逆反应。我们的模型由黑素细胞化合物（二羟基苯丙氨酸/褐黑素）的水溶液组成。用UVA照射这些溶液会导致其吸光度增加。缺氧会抑制溶液变黑，而光熄灭会导致吸光度降低，这与体内观察到的情况一致。使用防晒霜抑制模型反应的能力定义了一个UVA光防护参数（PUVA）。使用中性光束衰减器实现反应抑制的校准。PUVA定义为与测试防晒霜具有相同抑制效果的光束衰减器的吸光度百分比。给出了PUVA与迪菲-罗布森参数之间的相关性。这里开发的方法可在人体实验之前用作指示工具。
