Vitamin E Flashcards
What molecules are forms of vitamin E
Tocopherols and tocotrienols; activity as alpha-tocopherol
What is the difference between tocopherols and tocotrienols
Tocotrienols have double bonds
What are the R groups of alpha-tocopherol
Methyl groups (CH3)
What is the most potent form of vitamin E
alpha-tocopherol
How many sterioisomers does alpha-tocopherol have
8
What is the most potent sterioisomer form
RRR
What is the RDA for vitamin E
15mg/22.5IU
What are food sources of vitamin E
Sunflower seeds, almonds, sunflower oil
How is vitamin E absorbed
Lipid-soluble; follow the route of lipids
Vitamin E is not often eaten in free form; what is this bound molecule called
Alpha-tocopherol ester (bound to fatty acids)
What enzyme cleaves the ester from its bound molecule
Esterase
Where does esterase come from
Pancreas
Where does vitamin E go once absorbed
Chylomicrons; small amount to HDL
What cleaves vitamin E (and fatty acids) from chylomicrons
Lipoprotein lipase
What is a major excretion source of vitamin E
Bile (GI tract)
What are major carriers of vitamin E in blood (once cleaved from chylomicron)
Lipoproteins
What are two common molecules bound to alpha-tocopherol esters in synthetic forms of vitamin E
Tocopherol-acetate and tocopherol-succinate
What is vitamin E’s claim to fame
Antioxidant
What is formed after oxidation of vitamin E (alpha-tocopherol)
Alpha-tocopheroxyl radical (free radical, unstable)
What stabilizes alpha-tocopheroxyl radical
Oxidation (donates electron) or another antioxidant such as vitamin C (back to alpha-tocopherol-recycled)
What is formed alpha-tocopheroxyl radical is stabilized
8a-peroxy-alpha-tocopherol, alpha-tocopheryl quinone or tocopherol radical dimers
How is vitamin E expressed in RDA
Alpha-tocopherol equivalents
What is 1 IU of synthetic vitamin E esters
0.45mg RRR alphaTE
What is 1 IU of synthetic “natural” vitamin E
0.67 RRR alphaTE
