నైరూప్య

Effects of visible light in skin and hair and novel strategies of protection against photo damage

Christiane Pavani*, Lohanna F. Lopes, Mauricio S. Baptista

The interaction of light with skin is of fundamental importance for human health, however, excess of sun exposure causes damages to the skin and to the hair and consequently can accelerate skin aging, and cause skin cancer. It can also make your hair look ugly. The amount of light needed to maintain normal functioning of the epidermis and dermis, without harming them, certainly depends on the characteristics of each individual's skin. A biochemical route that critically depends on sun exposition is the activation of vitamin D. The continuous raise in the level of skin cancer, indicates that in addition to protecting the skin by blocking UVB and UVA, it is necessary to also consider the effect of other wavelength regions, such as the visible light. Since blocking visible light is a lot more challenging than blocking UV, it is important to consider other strategies of skin care, including maintenance of redox homeostasis. In this review, we will consider the basic photochemical reactions that are induced after light is absorbed by molecules present in the skin and in the hair, in each region of the sun spectrum, emphasizing the concepts of photosensitization and of oxidizing species, such singlet oxygen and free radicals. We will also look at the most important defenses against the redox misbalance and the biochemical routes important for the construction of the skin barrier function. We aim to discuss the opportunity for development of better strategies to prevent skin photoaging, as well as, hair damage.