[Vitamin C: structure-activity correlation and cytoprotective actions through free radical scavenging and...

Conventional studies on vitamin C have been conducted by single-dosage administration with ascorbic acid itself being so labile as to undergo irreversible degradation. In contrast, enrichment of intracellular ascorbate is accomplished by pro-vitamin C in which its 2,3-enediol moiety is protected with phosphate ester, being thereafter enzymatically esterolyzed. Ascorbic acid-2-O-phosphate (Asc2P) gradually releases ascorbate, which is cumulatively taken up into diverse human or mammalian cells, and prevents cell injuries such as post-ischemic reperfusional injury in the liver or heart, age-dependent telomeric DNA shortening in endothelial or epithelial cells, UV-B irradiational injury in the skin and lipid peroxide-induced injury in the vascular endothelium, and tumor invasion and metastasis.