NEW COMBINATIONS OF ANTIOXIDANTS Vitamin C with Vitamin E

As shown in Figure 3, the skin uses predominantly vitamin C to protect the aqueous environment and vitamin E to protect membranes from lipid peroxidation. Since vitamin C is naturally present intracellularly in relatively high concentrations, L-ascorbic acid not only acts directly as an antioxidant and as an essential cofactor in the synthesis of collagen, but also regenerates oxidized membrane vitamin E, so that the vitamin E need not be replaced (108). Oral vitamin C with E in high doses protects against UV-induced erythema in humans (109,110) whereas either vitamin alone is less effective (110). Alone each topical L-ascorbic acid (15%) and a-tocopherol (1%) give two-fold protection, whereas combined they provide four-fold protection against UV-induced erythema and thiamine dimer formation in porcine skin (111). This protection from UV-induced erythema (112) and tanning (113) by vitamins C and E combined with melatonin was further demonstrated in humans. Fortunately, mixing these hydrophilic and lipophilic antioxidants in a topical formulation stabilizes each (111) for a cosmetically attractive application.