Giacomoni reviews skin protection by the use of sunscreens, suntan, and antisun burn preparations. Until recently, the only strategy affording the protection of the skin against the harmful effects of solar radiation was to reduce the number of impinging photons with fabrics, umbrellas, hats, sunglasses or sunscreens. Diverting impinging photons is the first step in sun protection. Non-diverted photons enter the skin and provoke molecular damage to DNA, RNA, proteins, lipids and vitamins, often by indirect oxidative reactions. It is important to perform a second step and scavenge the reactive species, which provoke these residual reactions by antioxidants against different reactive oxygen species such as superoxide, hydroxyl radicals, and singlet oxygen. The third step in sun protection is to stimulate the endogenous self-defense responses. Today it is possible to stimulate DNA repair metabolically.
Enhancing skin barrier function: Beiersdorf discloses the use of substances that prevent the effects of nitric oxide synthase in cosmetic preparations for the enhancement of the skin barrier function. The invention concerns substances that inhibit nitric oxide synthase activity or block the expression of nitric oxide synthase in warm blooded organisms and their application in cosmetic and dermatological preparations to increase the effect of the skin barrier. An example of such a preparation is shown in Formula 1.