Description
Vitamin C (ascorbic acid) is part of the antioxidative defense system and is found in both the cytosol and extracellular spaces.
Vitamin C contributes to the antioxidative defense system in two different ways: it reacts with reactive oxygen species, especially peroxide radicals, and regenerates a-tocopherol (vitamin E). Vitamin C also has a pro-oxidative effect in combination with transition metals. It catalyses the reduction of Fe3+ to Fe2+. Due to the very small concentration of free transition metals in biological tissues, the antioxidative features are predominant. As a result of increased oxidative stress, the level of vitamin C is reduced in various syndromes, e.g. in HIV positive patients. Smoking causes a high consumption of vitamin C in the blood plasma. Protein thiols are oxidised and after the vitamin C pool has been depleted, lipid peroxidation begins.
