Free-radical damage by UV or hypoxanthine-xanthine oxidase in cultured human skin fibroblasts: Protective effects of two human plasma fractions.
Two in vitro methods to investigate free radical damage to cultured human skin fibroblasts have been used: irradiation with UVA or UVB, producing intracellular free radicals and DNA damage, or free radical production by the enzymatic system hypoxanthine-xanthine oxidase, releasing free radicals into the culture medium. These methods differ not only in the location of the free radicals generated but also in their nature and kinetics. The antioxidant properties of two human plasma extracts A and B (derived from Cohn's fraction IV and Cohn's fraction I + III) were investigated before, during and/or after the oxidative stress. Protection was observed when the fractions were added concomitantly with the enzymatic system (at 5 g/litre, fractions A and B exhibited, respectively, 77 and 50% activity) or during UVB irradiation (37 and 68% activity for fractions A and B, respectively at 5 g/litre). A small degree of protection was observed against UVA damage. No preventive or restorative effect was observed with the UVB system. The two fractions prevented UVA damage (at 2.5 g/litre, fraction A and B elicited 22 and 23% activity, respectively) but only fraction A also exhibited a restorative effect (at 5 g/litre, activity was 26%). One of the protective mechanisms could be the enhancement of intracellular antioxidant enzyme activity by incubation of cells with fractions A and B (after 24 hr of contact with fraction B, total glutathione peroxidase and glutathione peroxidase Se-dependent activities were significantly increased by 60 and 42%, respectively, compared with control values).
Masini
V
V
Laboratoire de Pharmacologie, Unité de Dermopharmacologie, Faculté de Pharmacie, Université Paris-sud, rue J.B. Clément, 92290 Châtenay-Malabry, France.
Noel-Hudson
M S
MS
Wepierre
J
J