| Abstract: | RRR-tocopherols currently draw attention as constituent of cosmetic preparations a. o. to prevent damage by over-exposure to sunlight. Because they only absorb part of the UVB and are transparent to UVA, their skin protective activity is supposed to be based on scavenging of reactive intermediates formed by ultraviolet radiation. To investigate this possibility, an in vivo method was developed. This is based on the determination of irreversible binding to epidermal DNA/RNA, proteins and lipids, of reactive intermediates formed by photodecomposition of a xenobiotic in the skin. The results support the conclusion that RRR-tocopherols can indeed scavenge reactive intermediates which are formed upon UV-exposure in the skin. RRR-tocopherol acetates also are active in this respect but only after pretreatment for some days (possibly because enzymatic hydrolysis of these compounds is a prerequisite). |
