Nitroxides are more efficient inhibitors of oxidative damage to calf skin collagen than antioxidant vitamins.
Reactive oxygen species generated upon UV-A exposure appear to play a major role in dermal connective tissue transformations including degradation of skin collagen. Here we investigate on oxidative damage to collagen achieved by exposure to (i) UV-A irradiation and to (ii) AAPH-derived radicals and on its possible prevention using synthetic and natural antioxidants. Oxidative damage was identified through SDS-PAGE, circular dichroism spectroscopy and quantification of protein carbonyl residues. Collagen (2 mg/ml) exposed to UV-A and to AAPH-derived radicals was degraded in a time- and dose-dependent manner. Upon UV-A exposure, maximum damage was observable at 730 kJ/m2 UV-A, found to be equivalent to roughly 2 h of sunshine, while exposure to 5 mM AAPH for 2 h at 50 degrees C lead to maximum collagen degradation. In both cases, dose-dependent protection was achieved by incubation with muM concentrations of nitroxide radicals, where the extent of protection was shown to be dictated by their structural differences whereas the vitamins E and C proved less efficient inhibitors of collagen damage. These results suggest that nitroxide radicals may be able to prevent oxidative injury to dermal tissues in vivo alternatively to commonly used natural antioxidants.
Venditti
Elisabetta
E
Istituto di Biochimica, Università Politecnica delle Marche, I-60131 Ancona, Italy.
Scirè
Andrea
A
Tanfani
Fabio
F
Greci
Lucedio
L
Damiani
Elisabetta
E
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000737:chemistry / Q000494:pharmacology; D002417:Cattle; D002942:Circular Dichroism; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D050050:Protein Carbonylation / Q000187:drug effects / Q000528:radiation effects; D012867:Skin / Q000378:metabolism; D013997:Time Factors; D014466:Ultraviolet Rays; D014810:Vitamin E / Q000737:chemistry / Q000494:pharmacology; D014815:Vitamins / Q000737:chemistry / Q000494:pharmacology*
D000975:Antioxidants; D009589:Nitrogen Oxides; D014815:Vitamins; D014810:Vitamin E; D003094:Collagen; D001205:Ascorbic Acid