TY - CHAP M1 - Book, Section TI - Antioxidants A1 - Baumann, Leslie A1 - Allemann, Inja Bogdan A2 - Baumann, Leslie A2 - Saghari, Sogol A2 - Weisberg, Edmund PY - 2009 T2 - Cosmetic Dermatology: Principles and Practice, 2e AB - The free radical theory of aging, proposed by Harman in 1956,1 is one of the most widely accepted theories to explain the cause of aging.2 Free radicals, also known as reactive oxygen species (ROS), are compounds formed when oxygen molecules combine with other molecules yielding an odd number of electrons. An oxygen molecule with paired electrons is stable; however, oxygen with an unpaired electron is “reactive” because it seeks and seizes electrons from vital components leaving them damaged.3 DNA, cytoskeletal elements, cellular proteins, and cellular membranes may all be adversely affected by activated oxygen species.4 ROS have not only been implicated in the overall aging process,5 but are believed to be involved cutaneously in causing photoaging, carcinogenesis, and inflammation. It is known that ultraviolet (UV)-induced damage to the skin is in part mediated by reactive oxygen intermediates.6 If antioxidants can absorb some of the resulting free radicals, they may be able to mitigate UV-induced damage to the skin. Free radicals may also lead to inflammation, which is believed to play a role in skin aging.6 Lipid peroxidation, another sequela of free radical production, causes harm to cell membranes and can lead to skin aging, atherosclerosis, and other signs of aging. Free radicals are also thought to contribute to the development of skin cancer. There are multiple studies in the literature describing the role of free radicals and skin cancer. The exact mechanisms for all of the detrimental effects of free radicals have not been completely elucidated, however. SN - PB - The McGraw-Hill Companies, Inc. CY - New York, NY Y2 - 2024/10/11 UR - dermatology.mhmedical.com/content.aspx?aid=1172448168 ER -