Skin low molecular weight antioxidants and their role in aging and in oxidative stress

The overall skin low molecular weight antioxidant (LMWA) capacity was evalu ated during the aging process and following exposure to oxidative stress. S everal invasive and non-invasive techniques were developed for evaluating t otal antioxidant activity. It was found that the skin possesses an extremel y efficient and unique antioxidant activity that is better than other tissu es. During the aging process a significant decrease in the levels and activ ity of the water-soluble LMWA was detected while no change and even a sligh t increase was recorded for the lipophilic LMWA. Similar results were obtai ned following exposure to oxidative stress. A significant decrease in the w ater soluble LMWA was recorded in all the stress induced procedures indicat ing a common mechanism of response. It has also been shown that along with the reduction in total water soluble antioxidant activity there is an accum ulation of oxidized adducts. This was observed both on the surface of the s kill and in deeper layers. It has been found that skin releases LMWA fi om its surface. This secretion phenomenon was found to be age dependent. Follo wing exposure to oxidative stress of various kinds, the release of LMWA fro m the skin was significantly enhanced. This may suggest a physiological mec hanism of the skill to cope with oxidative stress, which would open new pos sibilities for intervention. (C) 2000 Elsevier Science Ireland Ltd. All rig hts reserved.