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Vitamin C-driven free radical generation from iron
V Herbert1, S Shaw, E Jayatilleke
1The Mount Sinai and Bronx Veterans Affairs Medical Centers, New York City, NY, USA.
The Journal of Nutrition
|April 1, 1996
Summary
Free iron is toxic, but circulating proteins like transferrin and ferritin bind it. Ascorbic acid can release iron from ferritin, generating harmful free radicals, especially during inflammation.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Circulating free iron is toxic and can generate damaging free radicals.
- Humans utilize transferrin (high-affinity, low-capacity) and ferritin (low-affinity, high-capacity) to bind and sequester iron.
- Ferritin stores iron as Fe3, while transferrin delivers iron to cells via specific receptors.
Purpose of the Study:
- To investigate the role of ascorbic acid in iron release from ferritin.
- To elucidate the mechanism by which free iron generation occurs.
- To understand the differential behavior of ferritin and transferrin during inflammation.
Main Methods:
- In vitro analysis of iron binding and release mechanisms.
- Biochemical assays to measure iron oxidation states.
- Comparative analysis of serum protein levels in normal and inflamed states.
Main Results:
- Ascorbic acid can reduce Fe3 within ferritin to Fe2, facilitating iron leakage.
- Leaked Fe2 generates significant quantities of free radicals.
- Ferritin levels increase during inflammation (acute phase reactant), while transferrin levels decrease (reverse acute phase reactant).
Conclusions:
- Ascorbic acid poses a risk for iron-mediated free radical generation by interacting with ferritin.
- The distinct roles of ferritin and transferrin in iron homeostasis are highlighted, particularly their opposing responses to inflammation.