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Enzymatic antioxidants located in mitochondria and cytosol |
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Glutathione peroxidase (GSH) | Removal of H2O2, hydroperoxides |
Superoxide dismutase (SOD) | Catalytic removal of O2 |
Catalase (CAT) | Catalytic reduction of H2O2 to H2O |
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Nonenzymatic antioxidants located in cell membrane, exogenous dietary source |
Vitamin E (α tocopherol) | Chain-breaking antioxidant |
β-carotene | Scavenger of ROS, singlet O2 quencher |
Co-enzyme Q | Regenerates vitamin E |
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Compounds that reduce the availability of transition metals, Fenton reactions |
Transferrin | Sequesters iron and copper ions |
Lactoferrin | Sequesters iron at lower pH |
Albumin | Sequesters heme and copper |
Ceruloplasmin (ferroxidase) | Scavenges superoxide radical, binds copper ions |
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Scavengers, products of metabolism, exogenous dietary source |
Bilirubin | Scavenges peroxyl radical |
Uric acid | Scavenges hydroxyl radical |
Vitamin C (ascorbic acid) | Scavenges hydroxyl radical, recycles vitamin E |
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Thiol group donors |
Reduced glutathione (GSSH) | Binds free radicals, SH group oxidized to disulfide group (GSSG) |
α-lipoic acid | Recycles vitamin C, glutathione substitute |
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