Vitamin E Flashcards
what two classes is vitamin E divided into
- tocopherols (saturated)
2. tocotrienols (unsaturated)
what is the most biologically active form of vitamin E
RRR alpha-tocopherol (D-alpha-tocopherol)
individuals on __ diets may inadvertently limit their vitamin E uptake
low-fat
the in enterocyte, vitamin E is incorporated into ___ for transport through the lymphatic system ultimately reaching the circulation
chylomicrons
______ remnants deliver vitamin E to the liver using receptor mediated endocytosis
chylomicron
discrimination between the different vitamer forms of vitamin E does not occur during their absorption into the ______
small intestine or in their packaging into chylomicrons
in the liver RRR-alpha-tocopherol is incorporated into ___ for transport to the extrahepatic tissues
VLDL’s
a specific protein called _______ ,which is made in the liver, mediates the transfer of RRR-alpha-tocopherol into the VLDL’s
alpha-tocopherol transfer protein
the liver will secrete the other forms of vitamin E into the ____ via bile
feces
____ can interfere with the enzymes of vitamin K cycle
tocopherol quinone
oxidation of the phytyl tail by W and beta-oxidation lead to products called
alpha-carboxyethyl-hydroxychroman (alpha-CEHC)
high intakes of vitamin E can interfere with all other fat soluble vitamins like
beta-carotene
vitamin E can block the regeneration of the reduced form of vitamin ___, and thereby interfering with blood coagulation
K
why do some physicians recommend discontinuing vitamin E before surgery
risk of hemorrhaging
what 3 routes does RRR-alpha-tocopherol get to extrahepatic tissues
- LDL receptor mediated endocytosis
- lipoprotein lipase mediated uptake from VLDLs
- phospholipid transfer protein (PTP) facilitates vitamin E transfer from lipoproteins to cell phospholipid membrane
within cytoplasm of the cell, vitamin E ca bind to a specific tocopherol binding protein called
adenosine triphosphate binding cassette A1 (ABC A1)
tocopherol -> ___ -> tocopheroxyl radical
ascorbate glutathione or ubiquinone
vitamin E can inhibit protein kinase C by
dephosphorylation via activation of a specific protein phosphatase (PP2A)
how does vitamin E inhibit heard disease and stroke
- decrease LDL oxidation and decrease macrophage uptake
- decrease protein kinase C activity
- decrease monocyte endothelial adhesion
- decrease scavenger receptor expression: decrease oxidized LDL uptake
- decrease alpha-tropomyosin expression: decrease smooth muscle hypertrophy
- decrease monocyte SOD activity
- increase NO production: increase arterial dilation
- increase PGI2: decrease TXA2: increase vasodilation: decrease platelet aggregation
- increase carboxyethyl-hydroxychroman CEHC: decrease blood pressure
what 4 positive functions do tocotrienols have
- suppress activity of HMG-CoA reductase: reduce cholesterol synth
- increase HMG-CoA reductase degradation and decrease efficiency of translation of HMG-CoA reductase mRNA
- suppressed tumor cell angiogenesis
- prevent glutamate induced neurotoxicity (parkinsons and alzheimer’s)
what are the three increasing apoptosis mechanisms of gamma-tocotrienol
- increased pro-apoptotic BAX expression
- decreased anti-apoptotic BCL-2 expression
- decreased the oncogene Myc expression
vitamin E is shown to reduce the incidence of prostate cancer
T
there are no trials seen of vitamin E providing benefiting effects to those with parkinsons and alzheimers
T
vitamin E when taken with food may prevent heart disease, but no evidence it is preventative when taken it as a supplement
T
