Vitamin C: Vitamin C, or ascorbic acid. is essential for collagen production, but exerts its antioxidant effects by quenching free oxygen radicals produced by ultraviolet radiation and by assisting Vitamin E in protecting cell membranes.
Although the photoprotective effects of l-ascorbic acid are well established, it readily degrades in the presence of UV radiation, and does not penetrate the skin well, except at high concentrations and high acidty. Vitamin C esters, although more stable, have limited bioavailability when used topically.
Vitamin E: The active form of Vitamin E, alpha tocopherol, has been shown to inhibit enzymes which promote breakdown of collagen and to protect cell membranes from oxidation (lipid peroxidation). Contrary to popular opinion, topically applied vitamin E has not been demonstrated to have a significant effect on scar formation.
Spin Traps: Spin traps are special molecules that can trap and detoxify damaging free radicals which age the skin. They are commonly incorporated into preparations which include other antioxidants.
The term "spin trap" is derived from the technique used to detect and identify free radicals, electron spin resonance. The most commonly used spin traps are nitrone derivatives, such as 5,5,-dimethyl-1-pyrroline-N-oxide (DMPO), alpha-(4-pyridyl-1-oxide)-N-tert-butly nitrone (POBN), and alpha-phenyle-N-tertbutly nitrone (PBN), themselves stable free radicals. Reactive free radicals are attracted and bound to the beta carbon atom in the spin trap, forming a spin adduct and effectively "trapping" the free radical, allowing the structure of the trapped radical to be deduced.
Spin Traps show promise as blocking agents for inflammation caused by UV exposure. Unlike traditional sunscreens, which prevent UV mediated inflammation when used before exposure, spin trap compounds scavenge free radicals and minimize the inflammatory response during and for up to 12 hours after exposure to UV light. By interfering with the inflammatory cascade, these compounds may prevent collagen and elastin degradation, and thus premature aging of the skin.
Coenzyme Q10: Also known as ubiquinone, Coenzyme Q10 is a component of all cell membranes, and is a vital component of the electron transport chain. It acts to shuttle electrons in normal metabolism, trap free radicals, and help regenerate other antioxidants present in the cell, especially vitamin E.
CoQ10's role in oxidative metabolism and ATP synthesis has been well described. It acts primarily as a electron carrier in the mitochondria, with a more theoretical role as a cellular antioxidant. It has been postulated that CoQ10 may play a major role in preventing lipid peroxidation in mitochondrial membranes. Oral administration of CoQ10 has had some anecdotal benefit in patients with a variety of mitochondrial cytopathies and disorders of energy metabolism.
Idebenone: Similar in structure to Coenzyme Q10, idebenone is a more efficient free radical scavenger, and functions incidentally as an electron carrier. It has been used outside the U.S. for years as an anti-aging compound, as well as a cognition enhancer in patients with Alzheimer's disease and other neurologic disorders.
Alpha-lipoic acid (thioctic acid) is a potent antioxidant normally found inside cells, acting to protect delicate cellular membranes from free radical damage during normal cellular respiration
Resveratrol and Polydatin deserve special mention as the substances responsible for the "French Paradox"; that is, the very low incidence of heart disease in residents of Southern France, despite high rates of smoking and a diet high in saturated fats. This effect has been attributed to a high consumption of red wine, a rich source of resveratrol.
Resveratrol and Polydatins are glucopyranosides found in many fruits and vegetables, the highest concentrations being found in grape skins, which synthesize these compounds in response to exposure to UVA/B and fungal pathogens. Biologic activities of these glucopyranosides include potent free radical scavenging activity, with cardio- and neuroprotection and inhibition of lipid peroxidation similar to that seen with vitmins C and E.
Boldine
Glutathione
Beta-Carotene: occuring in many vegetables, notably carrots and tomatoes, this compound helps minimize lipid peroxidation of cell membranes, and is especially effective at quenching UV-induced singlet oxygen.
Anthocyanins: these bioflavonoid compounds, extracted from pine bark ("Pycnogenol") and grape seeds actively quench free radicals and potentiate the effect of vitamins C and E.
Green Tea extract contains antioxidant poyphenols which have been shown to protect against redness and swelling induced by UV radiation.
Ginko Biloba: Often used as a dietary supplement, Ginko Biloba leaves contain an assortment of polyphenols and bioflavonoids. In addition to antioxidant effects, Ginko Biloba extracts has been demonstrated to increase collagen production in cultured fibroblasts, although this effect has not been conclusively demonstrated in living skin.
Human Growth Factors: Harvested as a by-product of tissue-cultured human skin, various human growth factors have been incorporated into topical preparations, the best known of which is TNS Recovery Complex. These substances, essential for wound healing and recovery, have been shown to reduce the number and depth of wrinkles and fine lines, as well as improve skin texture and elasticity when used over time.
Some of the growth factors found in tissue culture media include transforming growth factor beta (TGF-B), vascular endothelial growth factor (VEGF), keratinocyte growth factor (KGF), and hepatocyte growth factor (HGF). Other substances found in cell culture media include matrix proteins, procollagens, interleukins, cytokines, and other compounds with biologic activity. As with any topical prepartion, penetration through the stratum corneum limits the bioavailability of these substances.
