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

The overall skin low molecular weight antioxidant (LMWA) capacity was evaluated during the aging process and following exposure to oxidative stress. Several invasive and non-invasive techniques were developed for evaluating total antioxidant activity. It was found that the skin possesses an extremely efficient and unique antioxidant activity that is better than other tissues. During the aging process a significant decrease in the levels and activity of the water-soluble LMWA was detected while no change and even a slight increase was recorded for the lipophilic LMWA. Similar results were obtained following exposure to oxidative stress. A significant decrease in the water soluble LMWA was recorded in all the stress induced procedures indicating a common mechanism of response. It has also been shown that along with the reduction in total water soluble antioxidant activity there is an accumulation of oxidized adducts. This was observed both on the surface of the skin and in deeper layers. It has been found that skin releases LMWA from its surface. This secretion phenomenon was found to be age dependent. Following exposure to oxidative stress of various kinds, the release of LMWA from the skin was significantly enhanced. This may suggest a physiological mechanism of the skin to cope with oxidative stress, which would open new possibilities for intervention. Copyright (C) 2000 Elsevier Science Ireland Ltd.