Differences in susceptibility to oxidative stress in the skin of Japanese and French subjects and physiological characteristics of their skin.

BACKGROUND

Many researchers have studied differences in conditions of ethnic skin using biophysical measurements. However, few studies to date have focused on the antioxidative capacity of the skin.

METHODS

We measured two parameters of oxidative stress in the stratum corneum, catalase activity and protein carbonylation of the stratum corneum (SCCP), in two ethnic groups, Japanese and French subjects, to characterize the susceptibility to oxidative stress. We also measured several physiological parameters at three different skin sites, two sun-exposed sites (cheek and dorsal aspect of the hand) and a sun-protected site (inner upper arm), in both ethnic groups.

RESULTS

Transepidermal water loss (TEWL), the size of corneocytes and skin color showed differences between sun-exposed and sun-protected sites regardless of ethnicity. Regarding ethnic differences, catalase activities and parameters of skin hydration and barrier function of Japanese subjects were higher than those of French subjects. However, SCCP values showed a trend contrary to catalase activity. The difference in the b* value indicated that the melanin content of Japanese skin was higher than that of French skin. Pearson's correlation analyses showed that catalase activity and SCCP values had weak relationships with water content, TEWL and skin color in both ethnic groups.

CONCLUSION

Differences in susceptibility to oxidative stress, namely melanin content and catalase activity in the skin, induce the better skin condition of Japanese compared with French subjects.