Cutaneous Photodamage, Oxidative Stress, and Topical Antioxidant Protection
This scientific review summarizes what is known about how photodamage occurs; why sunscreens—the current gold standard of photoprotection—are inadequate; and how topical AOs [Antioxidants] help protect against skin cancer and photoaging changes.
Sunlight coupled with living in an oxygen-rich atmosphere causes unwanted and deleterious stresses on skin…The most damage occurs from free radicals. Free radicals are defined as atoms or molecules with an unpaired electron…Together, these free radicals and reactive oxygen molecules are called ROS.
• The cell is well equipped to deal with most oxidative damage. Cellular integrity is maintained by enzymes, including catalase, glutathione reductase, and glutathione peroxidases, which collectively destroy hydrogen peroxide and lipid hydroperoxides.
• The skin naturally relies on AOs to protect it from oxidant stress generated by sunlight and pollution. A relative symphony of enzymic and nonenzymic AOs interacts to provide protection in both the intracellular and extracellular space.
• Because low-molecular-weight AOs protect skin against oxidative stress, undergoing depletion in the process, it should be desirable to add to the skin reservoir by applying the AOs directly to skin. Although AOs can be supplied to skin through diet and oral supplementation, physiologic processes related to absorption, solubility, and transport limit the amount that can be delivered into skin. Direct application has the added advantage of targeting the AOs to the area of skin needing the protection.
• Perhaps the most obvious candidates for topical AO protection are those naturally used by the body for photoprotection. Those include vitamin C, vitamin E, ubiquinol, and glutathione. Oxidative stress can occur from many sources in the skin including metabolism, pollution, and sunlight radiation. A wealth of information supports the photocarcinogenic damage to skin from sunlight and its relationship to oxidative stress.