MODULE 2: Vitamin C Flashcards
Reduced form of vit C
Ascorbate
Oxidized vitamin C form
Dehydroascorbate
Absorption of vit C occurs where?
Throughout small intestine especially jejunum
SVCT: what are and what do they transport
Specialized vitamin C transporters
Transport ASCORBATE
What form of vit C do GLUTs transport (before absorption)?
Dehydroascrobate
** % absorption of vitamin D relationship to DOSE SIZE
% absorption DECLINES with larger intake of vit C
** Where is vit C stored/in high concentrations?
WBCs Adrenals Pituitary Eyes Brain
Oxalic acid and kidney stones
Oxalic acid = metabolite of vit C metabolism/excretion
Oxalic acid likely contributes to kidney stones
** Vit C and Collagen Synthesis (involved in hydroxylations of what 2 amino acids?
Vit C involved in hydroxylations of proline and lysine (needed for synthesis of COLLAGEN)
** Vit C, scar tissue, would healing
Vit C involved in synthesis of COLLAGEN which are important for would healing/scar tissue
** Vit C and carnitine; function of carnitine
Vit C involved in SYNTHESIS of carnitine
Shuttle fatty acids into mitochondria (to enter TCA/Kreb)
** Vit C, hydroxylation, neurotransmitters (2 specific)
Vit C facilitated HYDROXYLATION is required for the synthesis of NOREPINEPHRINE and SEROTONIN
** Hydroxylation is process by which
HYDROXYL (OH) group is introduced to an organic compound (eg. Vit C hydroxylation required for synthesis of collagen)
** Vit C & neurotransmitter and hormone synthesis via a ideation of peptides LOOK UP
Safe
** Vit C and microsomal metabolism function/processing of complex molecules
Processes endogenous (cholesterol/hormones) and exogenous (toxins) substances
Acts as antioxidant during liver detox of complex molecules (dares ROS that are created during the detox pathways)
** Vit C and cholesterol
Aids in the conversion of cholesterol to BILE ACIDS
**Where does vit C act as an antioxidant in the body?
Aqueous tissue and tissue compartments (cytoplasm)
** What is antioxidant activity of vitamin C (describe what that means)
Vit C is able to donate it’s available electrons in OH and carbonyl groups to terminate ROS
** Ascorbate READILY gives up electrons to reduce free radicals
** In what occasion to vit C act as a PRO OXIDANT? Does it commonly occur?
Occurs during the interaction of ascorbate and minerals like IRON, COPPER
UNLIKELY to occur in the body (has only been seen in-Vivo)
Hesperadin and vit C (pulp?)
Hesperadin (flavonoid; anti ox found in CITRUS)
Found in HIGHEST concentrations in pith(white membranous part of citrus and white part of PEEL)
Should consume citrus food in FULL FORM
Pulp is HIGHER is vit C/antioxidants
Collagen is crucial for blood vessel X? And a fundamental protein for healthy ?
Blood vessel integrity
Healthy SKIN
Hesperadin and chronic inflammation
Anti inflammatory effects help reduce markers of chronic inflammation
Citrus bioflavonoids & BBB & antioxidant effects
Citrus bioflavanids (like hesperadin found in citrus fruit pith/membrane) can cross BBB and therefore exert antioxidant/anti inflammation effects in the brain
** What lifestyle factors drive down levels of vit C in the body
Intense exercise Smoking Alcohol consumption STRESS Medications (amount) Drug user
** HEMOCHROMATOSIS, vit C, & IRON (LOOK UP)
LOOK UP
Vitamin C and Osteoarthritis/Degenerative Joint Disease
Protective role of vit C on osteoarthritis osteoBLASTS
Antioxidant ability of vit C could help mediate decreased number of osteoblasts during again (that contribute to osteoarthritis)
- Can INCREASE LIFESPAN on osteoblasts !
** Food sources Vit C
Fruits and vegetables
- citrus!
- tomato
- Strawberries
- Green peppers etc.
** Synthesis of vitamin C in mammals (EXCEPT HUMANS); Enzyme necessary?
Mammals can make vitamin C from GLUCOSE but humans lack the necessary enzyme to do so
Enzyme = Gulonolactone oxidase
Function SVCT1
Main carrier responsible for intestinal vitamin C absorption
** Maximum body pool of vitamin C
2g
Cosubstrate
Loosely bound coenzymes
Function: Helps to FACILITATE REACTION OF ENZYMES
** # vitamin C hydroxylation reactions required for collagen synthesis
3
** Enzymes that vitamin C acts as a cofactors for in collagen synthesis; what amino acids are those enzymes used to form?
Prolyl hydroxylase (to make PROLINE)
Lysyl hydroxylase (to make LYSINE)
** Vitamin C, iron, collagen hydroxylation
Ascorbate acts as a REDUCING AGENT to convert oxidized iron (Fe3+) back to it’s reduced state (Fe2+) in the enzymes lysyl hydroxylase and prolyl hydroxylase
**Vit C function in collagen and carnitine synthesis
Vit C acts as reducing agent (of iron) during hydroxylation reaction required for the synthesis of carnitine and collagen
**Vitamin C hydroxylation function in norepinephrine synthesis
Norepinephrine is formed in the hydroxylation of the side chain of DOPAMINE
** reducing agent means electron ??
DONOR
** Vitamin C function: ANTIOXIDANT
Vitamin C acts as antioxidant in AQUEOUS environments (blood, within cell etc)
** Vitamin C, glutathione, vitamin E relationship
Vitamin C REGENERATES antioxidants glutathione and vitamin E by contacting electrons
** Non antioxidant functions of vitamin C
Collagen gene expression
Synthesis of bone matrix
Immune function
Is vitamin C an effective prophylactic in cold incidence reduction?
NO; reducing colds if used low dose daily
**Vitamin C and Iron interaction
Vitamin C ENHANCES absorption of IRON
** RDA males/females; should it every increase?
Males 90mg
Females 75mg
INCREASE DURING PREGNANCY/BREASTFEEDING
** Vit C: DEFICIENCY
Scurvy! Petechiae (ruptured small blood vessels) Bleeding gums Decaying teeth Abnormal wound healing
** Vit C deficiency FOUR H’s
4 H’s of scurvy Hemorrhagic Hyperkeratosis (hair follicles) Hypochondriasis Hematologic (Impaired collagen)
** Vit C TOXICITY
Osmotic diarrhea
Abdominal pain
KIDNEY STONES (for those with renal dysfunction)
** Upper limit vitamin C
2 g
** Catecholamine hydroxylation pathway (phenylalanine —> Epinephrine)
Phenylalanine —> L-Tyrosine —> L-Dopa —> Dopamine —> Norepinephrine —> Epinephrine
** Ascorbic acid acts as a pro-oxidant when???
Interacting with copper or iron; generates FREE RADICALS
** Vitamin C is needed for the hydroxylation of??
Serotonin
&
Norepinephrine
** Vitamins needed for carnitine synthesis
B6 & Vitamin C
** Toxicity of vitamin C can result in
Kidney stones (for those with renal dysfunction)
Excess iron absorption
