| Research Abstract |
L-Ascorbic Acid(ASA), which is also called Vitamin C, is an essential water soluble nutrient, and is widely known to be involved in the blo-synthesis of collagen, metabolism of aromatic amino acids, lipid metabolism, activation of immune system and cell multiplication. However, the detailed mechanism of the biological function of ASA is still unknown. Furthermore, ASA is widely used as antioxidant in food storage and processing making use of its very strong reducing property. Recently, there have been many reports which describe the relationship between the antioxidant function and biological function, however the details of their relationship is still unclear. In order to clarify the detailed correlation between the biological function and antioxidant function of ASA, both experimental and computational chemical methods were applied to elucidate these unresolved problems. First, the optimized structures of ASA and its related compounds were calculated, and other various physico-chemical parameters, such as electron densities, dipole moment, heat of formation etc., were obtained by semi-empirical molecular orbital calculations. The auto-oxidation reaction mechanism of ASA molecule with triplet oxygen molecule was also clarified. Identification of various auto-oxidation products including threonic acid and oxalic acid were made and confirmation of the production of super-oxide anion during the auto-oxidation of ASA was also made, Based on the results obtained in this study, a new auto-oxidation mechanism of ASA was proposed.
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