POSTADMINISTRATION PROTECTIVE EFFECT OF MAGNESIUM-L-ASCORBYL-PHOSPHATE ON THE DEVELOPMENT OF UVB-INDUCED CUTANEOUS DAMAGE IN MICE

The effects of stable vitamin C, magnesium-L-ascorbyl-2-phosphate (MAP ), administered after acute and chronic exposure to UVB irradiation we re investigated using hairless mice, Intraperitoneal administration of 100 mg/kg of MAP immediately after acute exposure to 15 kJ/m(2) of UV B significantly prevented increases of UVB-induced lipid peroxidation in skin and sialic acid in serum, an inflammation marker, Administrati on of 50 mg/kg of MAP immediately after each exposure significantly de layed skin tumor formation and hyperplasia induced by chronic exposure to 2 kJ/m(2) of UVB, Intraperitoneal administration of 200 mg/kg of M AP produced an increase in ascorbic acid (As) levels in the serum, liv er and skin within 15 min. Serum As levels quickly returned to normal, but hepatic and cutaneous levels remained elevated before returning t o normal after 24 h, suggesting that MAP was converted to As in the se rum and in those tissues. Ultraviolet B-induced hydroxyl radical gener ation in murine skin homogenates was scavenged by As-Na addition, whic h was directly detected by electron spin resonance (ESR), These result s suggest that postadministration of MAP delays progression of skin da mage induced by UVB irradiation. It is presumed that MAP, once convert ed to As, exhibits such inhibitory effects by scavenging hydroxyl and lipid radicals generated as a direct or indirect result of UVB exposur e.