Effects of ultraviolet A and B irradiation on lipid peroxidation and activity of the antioxidant enzymes in keratinocytes in culture.

Human keratinocytes (NCTC 2544) in culture were exposed to various combinations of ultraviolet A (UVA) and UVB irradiation and at 0.5 h postirradiation the level of lipid peroxidation and activities of antioxidant enzymes were measured. The results suggest that UV irradiation is capable of inducing lipid peroxidation reactions, as parameters of which the amount of thiobarbituric acid-reactive material and the number of conjugated diene double bonds were measured. Both UVA and UVB irradiation were also found to affect the activities of antioxidant enzymes. Following UVB irradiation the activity of superoxide dismutase (Cu/Zn form) was decreased, and combination of increasing doses of UVA irradiation to a given dose of UVB irradiation decreased the activity of both catalase and superoxide dismutase. In summary, this study suggests that both UVA and UVB irradiation are capable of inducing lipid peroxidation reactions and an impairment of the enzymic antioxidant system in human keratinocytes in culture.