Importance 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

15. 2.) ANTI-OXIDANTS
Are nutrients that block some of the damage
caused by free radicals

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.

19. SOURCES:
Fruits
Vegetables
Animal products
Fish

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.

21. Recommended Dietary Allowance

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.