1. Kyoritsu College of Pharmacy, Tokyo 105-8512, Japan
2. ^*Central Research Laboratory, Showa Denko Co., Ltd, Chiba City, Japan

Correspondence: Shizuko Kobayashi, Ph.D., Kyoritsu College of Pharmacy, Shibakoen 1-5-30, Minato-ku, Tokyo 105, Japan. Email: kobayashi-sz@kyoritsu-ph.ac.jp

Received 18 October 2002; Revised 9 January 2003; Accepted 6 March 2003; Published online 23 July 2003.

Abstract

The ability of the novel water-soluble provitamin E, -tocopherol-6-O-phosphate, to protect against ultraviolet B-induced damage in cultured mouse skin was investigated and compared with the protectiveness of -tocopherol acetate in cultured mouse skin. Pretreatment of skin with 0.5% (9.4 mM) -tocopherol-6-O-phosphate in medium for 3 h significantly prevented such photodamage as sunburn cell formation, DNA degradation, and lipid peroxidation, which were induced in control cultured skin by a single dose of ultraviolet B irradiation at 0 to 40 kJ per m² (290–380 nm, maximum 312 nm). This protection was greater than that seen with -tocopherol acetate, the most common provitamin E that is used in commercial human skin care products. The concentration of -tocopherol in cultured skin pretreated with 0.5% -tocopherol-6-O-phosphate rose to approximately two to three times that found in the control skin and the reduction in cutaneous -tocopherol that was induced by ultraviolet irradiation was significantly inhibited. In the group pretreated with 0.5% -tocopherol acetate, however, conversion of -tocopherol acetate to -tocopherol was not observed, although the level of provitamin incorporated into the cultured skin was the same as that for -tocopherol-6-O-phosphate. These findings indicated that the enhanced ability of -tocopherol-6-O-phosphate to protect against ultraviolet B-induced skin damage compared with -tocopherol acetate may have been due to -tocopherol-6-O-phosphate's conversion to -tocopherol. Moreover, following pretreatment with a 0.5% -tocopherol-6-O-phosphate, -tocopherol-6-O-phosphate was incorporated into the human skin in a three-dimensional model and 5% of the incorporated -tocopherol-6-O-phosphate was converted to -tocopherol. These results suggest that treatment with the novel provitamin E, -tocopherol-6-O-phosphate may be useful in preventing ultraviolet-induced human skin damage.