Cutaneous vitamins A and E in the context of ultraviolet- or chemically-induced oxidative stress

Vitamins A and E are present in mammalian skin. Although the main circulati ng form of vitamin A in the blood is retinol, the epidermis stores it as re tinyl esters. The epidermis can be easily loaded with high amounts of vitam in A by topical application of either retinol or retinaldehyde, two well-to lerated precursors of the biologically active retinoic acid, while topical alpha -tocopherol loads the epidermis with vitamin E. The probable physiolo gical function of epidermal vitamin E is to contribute to the antioxidant d efense of the skin, whereas that of epidermal vitamin A (retinol and retiny l esters) is not yet well understood. Besides being a precursor for retinoi c acid, vitamin A also has a free radical scavenging potential. Due to thei r physical properties, vitamins A and E absorb ultraviolet (UV) light in th e region of solar spectrum that is responsible for most of the deleterious biological effects of the sun. In the mouse, topical vitamin A has been sho wn to prevent the UV-induced epidermal hypovitaminosis A, while topical vit amin E prevents oxidative stress and cutaneous and systemic immunosuppressi on elicited by UV. Thus constitutive epidermal vitamins A and E appear comp lementary in preventing UV-induced deleterious cutaneous and systemic effec ts, and these properties can be reinforced by topical application of retino l or retinaldehyde and topical alpha -tocopherol. Copyright (C) 2001 S. Kar ger AG, Basel.