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Role of vitamin c in immunity
1. MARY EDELYN A. ATILANO, RN
BURAIDAH CENTRAL HOSPITAL
AL QASSIM, KSA
2. INTRODUCTION:
Vitamin C, also known as ascorbic acid and L-ascorbic acid.
is a vitamin found in food and used as a dietary supplement.
It is needed for metabolic reactions in all plants and animals
including H+ ion transfer and maintenance of intracellular redox
potential.
The human being is one of the few mammals unable to
synthesize vitamin C.
Other animals unable to synthesize vitamin C include
primates, fruit bats, guinea pigs, and some birds.
The inability to synthesize vitamin C results from the lack
of gulonolactone oxidase, the last enzyme in the vitamin C
synthetic pathway.
3. The chemical name of ascorbic acid (vitamin c) is L-
ascorbic acid.
Ascorbic acid (vitamin c) is freely soluble in water;
sparingly soluble in alcohol; insoluble in chloroform, in
ether, and in benzene.
Molecular weight is 176.13 g/mol
The empirical formula is C6H8O6
Ascorbic acid in biological system (low pH)
:CHEMICAL & PHYSICAL PROPERTIES
4. Ascorbate in neutral salutation (pH>5)
Ascorbate and ascorbic acid are both naturally present in the
body, since the forms interconvert according to Ph.
Occurs as a white or slightly yellow crystal or powder with a
slight acidic taste. On exposure to light, it gradually darkens.
In the dry state, it is reasonably stable in air, but in solution it
rapidly oxidizes.
Ascorbic acid is a hexose derivative & closely resembles
monosaccharide's in structure.
Vitamin C exists in two forms:
L – ascorbic acid (reduces form)
L – Dehydro ascorbic acid (oxidized form)
5. L – ascorbic acid undergoes oxidation to form dehydro ascorbic acid
& it is reversible reaction.
Ascorbic acid & dehydro ascorbic acid are biologically active.
D – ascorbic acid is biologically inactive
Vitamin C is heat labile
It is readily absorbed from stomach & small intestine, is present in
the tissues as ascorbic acid & dehydro ascorbic acid
Oxidation of ascorbic acid is rapid in the presence of copper.
6. Vitamin C is the generic descriptor for all compounds
exhibiting qualitatively the biological activity of ascorbic acid.
The terms L-ascorbic acid and ascorbic acid are both trivial
designators for the compound 2,3-didehydro-L-threo-hexano-
1,4-lactone.
The oxidized form of this compound is called L-
dehydroascorbic acid or dehydroascorbic acid.
:STRUCTURE
7. PRODUCTION:
Vitamin C has been produced commercially by
extraction from plants, by chemical synthesis, by
fermentation and by mixed fermentation/chemical
synthesis methods.
The manufacture of vitamin C is now carried out
in two ways:
1. Traditional Reichstein process
2. Newer two-stage fermentation process
8. 1. COLLAGEN SYNTHESIS:
Most abundant protein found in the body.
Vitamin C is necessary for collagen synthesis.
Collagen is a structural protein found in skin, bones, tendons, and cartilage.
All collagen (n~19) have a triple helical structure.
For the collagen molecule to aggregate into its triple-helix configuration
selected proline residues must be hydroxylated forming hydroxyproline.
Requires di-oxygenase enzymes, reduced iron (Fe+2), ascorbate.
Vitamin C role:
During hydroxylation, iron cofactor in the enzymes is oxidized,
(ferrous(2+) state ---- ferric (3+) state).
Ascorbate is needed to function as a reductant thereby reducing iron back
to its ferrous (2+) in prolyl and lysyl hydroxylases.
FUNCTIONS & MECHANISM OF ACTION:
9. 2. CARNITINE
SYNTHESIS
Carnitine is a methylated from nitrogen containing compound
made from lysine.
Sufficient carnitine is critical in fat metabolism, because it is
essential to transport long- chain fatty acids from cell
cytoplasm into mitochondrial matrix where β-oxidation occurs.
Vitamin C role:
Required for 2 hydroxylation reaction in synthesis carnitine,
which functions as preferred reducing agent, specifically
reducing Fe from ferric (Fe3+ ) back to ferrous state (Fe2+
).
10. 3. TYROSINE SYNTHESIS &
CATABOLISM
Hydroxylation of phenylalanine
Requires phenylalanine mono-oxygenase (hydroxylase), Fe+2.
O2.,tetrahydrobiopterin, NADPH, vitamin C
Vitamin C regenerating tetrahydro-biopterin from dihydrobiopterin.
Occurs in liver and kidney.
Tyrosine catabolism require ascorbate as reductant for hydroxylases
Cu-dependent enzyme p-hydroxyphyenylpyruvate (dioxygenase)
Fe-dependent enzyme homogentisate dioxygenase.
11. 4. NEUROTRANSMITTER
SYNTHESIS
Vitamin C maintains mineral cofactors for some of
the enzymes involved in synthesis of
neurotransmitters in its reduced state (
Norepinephrine ).
It is generated from hydroxylation of dopamine side
chain.
This reaction catalyzed by dopamine monoxygenase
(contain 8 Cu atoms)-vitamin C- dependent reaction.
Found in nervous tissue and adrenal medulla.
12. Neurotransmitter synthesis
Serotonin
Hydroxylation of tryptophan (in brain)
Requires tryptophan mono-oxygenase (hydroxylase), O2
tetrahydrobiopterin, vitamin C. first step in serotonin synthesis.
Serotonin
13. Other Neurotransmitters and Hormones
keeping Cu in reduced for peptidylgycine α-
amidating mono- oxygenase.
Many of amidated peptides are active as
hormones, such as calcitonin, CCK and
gastrin.
The enzyme found in pituitary , adrenal,
thyroid glands and brain.
14. 1.) GROWTH AND REPAIR OF
TISSUES
Form an important protein used to make skin,
tendons, ligaments, and blood vessels.
Heal wounds and form scar tissue
Repair and maintain cartilage, bones, and teeth.
:USES
16. Anti-oxidants
activity:
The reduction potential of ascorbate is such that it readily
donates electrons/hydrogen ions to regenerate other
antioxidants, such as vitamin E, glutathione, and uric
acid, and to reduce numerous reactive oxygen (ROS) and
nitrogen species (RNS).
Ascorbic acid interact with oxidants in the aqueous phase
(blood or intracellular) before they initiate damage in
nucleus, cell lipids.
Ascorbate = thiols > bilirubin > uric acid > vitamin E
17. Pro-oxidants activity:
Vitamin C can reduce transition metals, while itself
becoming oxidized to semidehydroascorbate:
These reduced metal ions can cause cell damage by
generating ROS and free radicals.
18. 3.) A REMEDY FOR COMMON
COLDS
Vitamin C is thought to moderate colds by enhancing
many immune cell (such as some leukocyte) functions
while also destroying histamine, which causes many of a
cold’s symptoms.
4.) Vitamin C helps absorb Iron (Fe)
5.) Vitamin C protects against immune system
deficiencies, cardio vascular disease, prenatal health
problems, eye disease, and skin wrinkling.
20. How does Vitamin C works?
Vitamin C reaches every cell of the body and
plays a role in the making and protecting of our
connective tissue that holds the body together.
Helps the immune system fight off diseases.
Helps the cardiovascular system by facilitating fat
metabolism
Helps the nervous system by converting amino
acids into neurotransmitters
Vitamin C’s formation of collagen protects teeth
and bones.
22. Vitamin C Deficiency:
Scurvy is an avitaminosis resulting from lack of vitamin C
Symptoms:
Adults: gingivitis, bleeding tooth; under periosteal hematoma,
petechiae, increased thickening of the hair follicle.
If left untreated can be fatal due to massive bleeding or ischemic
cardiomyopathy.
Infantile scurvy (Barlow's disease):
infants have pain when they move & lose their appetite.
Infants do not gain weight as they normally do
In infants & children bone growth is impaired & bleeding &
anemia may occur
23. Excess of Vitamin C:
Vitamin C is a less accrued but if high doses for a long
time, can create oxalate stones (oxalic acid from
dehydroascorbic converted), or urate stones, sometimes
on both stones; come loose, digestive disorders.
24. REFERENCES:
Webb A.L., Villamor E. Update: Effects of antioxidant and non-
antioxidant vitamin supplementation on immune function. Nutr.
Rev. 2007
Hemila H. Vitamin C and Infections. Nutrients. 2017
www.slideshare.com
www.wikipedia.com
Harper’s Biochemistry 25th Edition, 2015
www.Pubchem.com
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and
Health. Elsevier Inc. 2008. April 13, 2018, Rev.