角層中における過酸化脂質及び皮表脂質の分布と洗浄による除去

抄録

A new method, a combination of the tape-stripped and paper-absorbent methods, was developed for measuring the distribution of peroxide and skin surface lipids on their depth in human stratum corneum. Peroxide lipids were shown to be produced not only in the top layer of the stratum corneum in the skin of people not exposed to sunlight but in the deep layer as well. Their compositions were correlated to those of skin surface lipids. Peroxide lipids in the outer layer were more easily produced than those in inner layers, possibly due to higher squalene content in the outer lipids. The removal of peroxide and skin surface lipids from the stratum corneum was also conducted and the washing properties were noted to differ. Peroxide lipids not only in the outer layer but also in the inner layer could be washed away while washing removed skin surface lipids only from the top layer. The addition of a cleanser enhanced removal efficiency.
The removal efficiency of three surfactants differing in hydrophilic groups, i.e. phosphate, sulfate and carboxylate groups, was assessed. The phosphate type surfactant was found more capable of removing skin surface lipids in the stratum corneum.
Based on the present results, an ideal cleanser should wash away peroxide lipids situated deeply within and harmful to the skin, but only skin surface lipids which function as a surfactant barrier.