ANTIOXIDANT AND PRO-OXIDANT EFFECT OF ASCORBIC ACID
Free
radicals attack proteins, lipids, enzymes andDNAcausing pathological changes in
organism. There are many mechanisms that organism uses to fight against free
radicals. Ascorbic acid is one of the strongest reducers and eliminators of free
radicals. It reduces stable oxygenic, azoth and thyol radicals and acts as a
primary defense against water radicals in blood. When radicals are dissolved in
water suspensions of erythrocytes and low density lipoproteins (LDL), ascorbic
acid catches and eliminates free radicals before they arrive to the membrane and
LDL molecules. Even though ascorbic acid is not capable of eliminating free
radicals out of fluid medium, it acts as synergist to alpha-tocopherol in lipid
section, contributes to the lessening of lipid tocoperoxil radicals, and above
all, regenerates alpha-tocopherol. Ascorbic acid may act as pro-oxidant under in
vitro conditions in the presence of metals; however, this effect is probably not
important under in vivo conditions where metal ions, being sequestered, become
second reducers. Acta Medica Medianae 2005; 44(1): 65-68.
Key words: ascorbic acid, vitamin E, free radicals,
lipid per-oxidation