Oral and systemic photoprotection

Abstract

Excessive exposure to solar radiation brings up two types of deleterious effects. Short term, the leading clinical effect is erythema, which includes swelling and redness, inflammation, and burning sensation. Long term, the predominant effect is photoaging, characterized by skin deterioration, susceptibility to develop skin cancer, and dramatic cosmetic consequences. Erythema is mainly caused by shorter wavelength UV photons that damage tissue, cell, and DNA alike. Photoaging is due to the transformative effect of longer wavelength and low-energy radiation, which causes oxidative damage, activates matrix metalloproteinases, and promotes DNA mutation. Conventional sunscreens protect against UV-induced erythema and photoaging. Broad-spectrum sunscreens are particularly useful to inhibit epidermal gene modifications like mutations on p53 gene, generation of thymine dimers, and induction of apoptosis or to minimize enzymatic damage to the dermal matrix (Seite et al., Photodermatol Photoimmunol Photomed 16(4):147–155, 2000; Moyal, Eur J Dermatol 8(3):209–211, 1998; van der Pols et al., Am J Epidemiol 163(11):982–988, 2006; Al Mahroos et al., Arch Dermatol 138(11):1480–1485, 2002; Bernerd et al., Photochem Photobiol 71(3):314–320, 2000).New agents with photoprotective capabilities, some of them following oral or subcutaneous administration, have been recently developed. These prevent, ameliorate, or even repair solar-induced skin damage. Furthermore, chemoprevention via nontoxic agents, especially botanical antioxidants, constitutes a plausible strategy for prevention of acute and chronic photodamage including photocarcinogenesis.In this chapter, we describe the state-of-the-art status of non-topical forms of photoprotective agents and substances with photoprotective properties. Evaluation of these agents in terms of photoprotection will also be discussed.