Reduction of UVB/A-generated free radicals by sodium L-ascorbyl-2-phosphate in cultured mouse skin

Abstract

The quenching abilities of sodium L-ascorbyl-2-phosphate (APS) and ascorbic acid 2-glucose (AG) against UVB/A-generated free radicals in cultured mouse skin were investigated using electron spin resonance (ESR). The relation between their quenching ability and protective effects against photodamage were also compared to those of ascorbic acid (AsA) pretreatment. Both APS and AG were able to scavenge UVB/A-generated hydroxyl radicals under aqueous conditions (pH 7.2) in a manner similar to that seen with AsA; however, APS was a more effective scavenger than AG. Similar results were obtained ex vivo. Both derivatives could protect skin from UVB/A-induced photodamage, as determined by a reduction in the presence of sunburn cells and DNA fragmentation. However, AsA pretreatment had the weakest protective effect, even though cutaneous, its level was the highest among the three agents tested before irradiation. These results indicated that the superior protective effect of APS is related to its direct free radical scavenging ability, rather than to its conversion to AsA.