Exam 2, B6 Flashcards
vitamin B6 name
pyridoxine
pyridoxine structure
hexose but with more things attached
Paul Gyorgy + what vitamin is he relevant to
cured dermatitis in rats, discovered lactobacillus bifidus growth factor activity in human milk
what is the B6 form in supplements
pyridoxine (alcohol form)
what is the main B6 form, the most active
pyridoxal (aldehyde form)
Esmond Snell
discovered 2 forms of B6
what is necessary for absorption of pyridoxine
Zinc because alkaline phosphatases are dependent of it to breakdown B6
pyridoxine coenzyme
PLP
how is PLP found in the body
-most bound to albumin
-10% stored in liver, 80% bound to glycogen to protect it
main function of pyridoxine
protein, fat and carb metabolism but especially amino acid metabolism
what types of reactions are involved in AA metabolism?
deamination, decarboxylation, cleavage, transamination, transulfhydration, transelenation
what happens in transulfhydration
breakdown of homocysteine (increased in CVD, alzheimer’s and parkinson’s)
why does a pyridoxine deficiency cause hypochromic, microcytic anemia?
PLP is the first step in heme synthesis, so no B6 = low color and small cell
what accounts for 1/2 of B6 usage in the body
glycogen degradation for glucose homeostasis
what other deficiencies can cause hypochromic microcytic anemia
Fe, copper
what deficiencies cause Macrocytic anemia
B12, folic aid
B6 relationship to B3
niacin (B3) is synthesized from tryptophan and nucleic acid production thanks to B6
*basically, synthesis of NAD requires B6
what is PLP non-coenzyme role
gene expression
deficiency of vitamin B6 symptoms
-seborrheic dermatitis
-weakness, fatigue
-mental disability, retardation, convulsive seizures
-antibody impairment at risk (low grade inflammation)
photo: rat with irritated eye
dermatitis: B6 deficiency
photo: chicken with inflamed edema of eyelids
dermatitis: B6 deficiency
photo: pig on the floor
epileptic-like seizures: B6 deficiency
best indicator of B6 stores
plasma PLP
toxicity of B6 + TUIL
-2 to 6 grams for 2-40 months
-100 mg/day
-cause sensory neuropathy: unsteady gait, impaired tendon reflexes and motor control + lesions of skin
RDI for B6
1.3 mg/ day
why does supplementing B6 cause toxicity*
supplements are in form of pyridoxine (alcohol form) which competes for enzyme pyridoxal phosphate, so it would inhibit the conversion to active forms. also excess B6 (and B12) could lead to neuropathy
main source of B6
tuna, cooked
