Rosmarinic acid, a photo-protective agent against UV and other ionizing radiations.

Solar UV and other ionizing radiations cause a generation of reactive oxygen species, induce cellular DNA damage and alter skin homeostasis. The use of exogenous antioxidants is increasingly frequents, we attempt to demonstrate that a rosmarinic acid extract acts as photo-protector; both free radical scavenger as an inducer of the body's own endogenous defence mechanisms by regulating tyrosinase activity and stimulating melanin production. Malonyldialdehyde formation (TBARS) was delayed when RA was used. The protection factor was 3.24 times vs AA. TEAC value for RA was 1.6 times vs AA. The radioprotective-antimutagenic effects of RA were measure using the micronucleus test. The level of micronucleous for treatments before irradiation was: RA [14]<AA [22]<DMSO [28]<Control [32], and after irradiation was: RA [23]<AA [25]<DMSO [31]<Control [32]. RA increased the Tyr activity and its expression level in B16 melanoma cells after stimulation lasting 48 h compared with the negative control. In vivo experiments show the capacity of RA orally administered to inhibit cutaneous alterations caused by UVA exposure (skin photocarcinogenesis). Therefore, according all these experiences, RA can be proposed as a proper photo-protective agent.