Beneficial effects of quercetin on oxidative stress induced by ultravioletA

Cells exposed to ultraviolet A (UVA) radiation can induce the production of reactive oxygen species (ROS) that may damage cellular elements. By contra st, antioxidants can reduce production of ROS. To assess these cellular eve nts in a model system, rats were divided into three groups comprising contr ol (C), ultraviolet exposed (UV), and ultraviolet exposed and quercetin-tre ated (UV + Q). UV and UV + Q group rats were irradiated 4 h/day with UVA ra diation (1.25 mW/cm(2)) for 9 days. In the UV + Q group rats quercetin (50 mg/kg body weight) was administered intraperitoneally before irradiation. T he levels of malondialdehyde (MDA) were increased significantly following i rradiation (P < 0.001). In the UV + Q group MDA levels declined significant ly compared with the UV group (P < 0.001). With respect to levels of glutat hione (GSH), no statistically significant changes were found between the co ntrol and the UV group. The GSH levels in the UV + Q group were slightly hi gher than those of the control and UV groups, but not significantly so. The enzyme activities of glutathione peroxidase, glutathione reductase, catala se and superoxide dismutase decreased significantly after irradiation (P < 0.001). In the UV + Q group all of these enzyme activities were found to be considerably higher than those in the UV group (P < 0.001). This study dem onstrates that exposure of rats to UVA leads to oxidative stress as reflect ed by increased MDA levels and reduced enzymatic antioxidant levels. It als o shows that quercetin may be useful in reducing or preventing photobiologi c damage.