Effect of topical corticosteroids on the activity of superoxide dismutase in human skin in vitro.

We measured the superoxide dismutase (SOD) activity in human skin from tissue homogenates after topical application of hydrocortisone-21-acetate and clobetasol proprionate, dissolved in propylene glycol. SOD was measured spectrophotometrically. SOD activity was higher in the treated skin than in the control untreated skin. We separated epidermis from the dermis by curettage and measured the level of SOD in each homogenized layer; SOD activity was higher in the epidermis compared to the dermis in untreated skin. After corticoid application, SOD activity was higher in the dermis compared to the epidermis to a degree dependent on corticoid potency. These experiments demonstrate that the epidermis may have a role in the barrier function of the skin by its antioxidant capacity and that the dermis is the major location of the metabolic activity in the skin. On the other hand, our results suggest that these corticosteroids may stimulate SOD production and may release antioxidants. This could be another anti-inflammatory property of corticosteroids.