From UV Protection Combinations to Solid Dialkyl Ketones in Cosmetics

By: Charles Fox

Posted: October 17, 2006, from the November 2003 issue of Cosmetics & Toiletries.

Combinations for UV protection: Lin et al. have published on UV protection by a combination of topical antioxidants, vitamin C and vitamin E.  The skin naturally uses antioxidants to protect itself from the damaging effects of sunlight. The skin also predominantly uses L-ascorbic acid (vitamin C) to protect the aqueous environment and α-tocopherol (vitamin E) to protect lipid structures including membranes. In many biological systems, vitamins C and E work synergistically. When vitamin E becomes oxidized by free radicals, it is regenerated in the membrane by vitamin C. L-ascorbic acid is the major fl uid-phase antioxidant; glutathione protects the intercellular compartment and vitamin E and ubiquinol protect membranes.

On a molar basis L-ascorbic acid is the predominant antioxidant in skin. Its concentration is 15-fold greater than glutathione, 200-fold greater than vitamin E, and 100-fold greater than ubiquinol/ ubiquinone. Concentrations of antioxidants are higher in the epidermis than in the dermis. In aged and photodamaged skin, levels of α-tocopherol and L-ascorbic acid were reduced signifi cantly – by as much as 60-70%.7 UV irradiation depletes ubiquinol and vitamin E whereas L-ascorbic acid is relatively resistant.

This is only an excerpt of the full article that appeared in Cosmetics & Toiletries, but you can purchase the full-text version.