PROTECTIVE EFFECT OF MAGNESIUM-L-ASCORBYL-2 PHOSPHATE AGAINST SKIN DAMAGE-INDUCED BY UVB IRRADIATION

The protective effect of magnesium-L-ascorbyl-2-phosphate (MAP) on cut aneous photodamage such as lipid peroxidation and inflammation induced by ultraviolet B (UVB) exposure (290-320 nm, max. 312 nm) was investi gated using hairless mice. When MAP was administered intraperitoneally to mice at a dose of 100 mg of ascorbic acid (AS) per kg body weight base immediately before irradiation (15 kJ/m(2)), the expected increas es in thiobarbituric acid reactive substance (TEARS) formation in skin and serum sialic acid, indices of Lipid peroxidation and inflammatory reaction, respectively, were significantly reduced, However, the expe cted decrease in the level of cutaneous AS was unchanged, Similar resu lts were observed for animals given 100 mg of AS-Na per kg body weight before UVB irradiation. When MAP was administered intracutaneously im mediately before irradiation, the expected UVB-induced increases in TE ARS and sialic acid were again significantly prevented, Ascorbic acid- Na had a less protective effect than intracutaneous MAP administration , The cutaneous AS level was significantly higher in the MAP-treated m ice than in the controls, and the UVB-induced decrease in tissue AS wa s prevented by intracutaneous MAP administration, These results sugges t that MAP protects against UVB irradiation-induced lipid peroxidation and inflammation in cutaneous tissue, regardless of the drug administ ration route, We found, in an in vitro experiment, that MAP was conver ted to AS as it crossed the epidermis, but that AS-Na did not pass thr ough the epidermis, Furthermore, PI IAP was also converted to AS in se rum, These results suggest that the protective effect of MAP on UVB-in duced cutaneous damage is due to conversion of MAP to AS.