VITAMIN C

PRESENTED TO DR.ASMA RAZAQ PRESENTED BY ROSHEEN ZAFAR 1507 PHARM-D

(LAHORE COLLEGE OF PHARMACEUTICAL SCIENCES )

CONTEXT

DAILY INTAKE

History Of Vitamin Vitamin C was isolated in 1928, and its structure

was determined in 1933. The problems referred to as scurvy and

associated with lack of vitamin C had been quite prevalent for centuries. Some of the most notable stories are those of the British sailors who often died from scurvy on seas.

Vitamin C Vitamin C, also known as L-ascorbic acid, is a

water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component.

Ascorbic acid

CHEMISTRY Ascorbic acid have similar configuration to that

of the sugar L-Glucose .

The presence of the ascorbate ion that contributes to vitamin C’s role as a strong reducing agent (antioxidant).

It is stable in solid form and in acidic solutions but is rapidly destroyed in alkaline solutions.

Oxidative destruction of ascorbic acid is accelerated by increasing pH.

e.g silver and cupric ions accelerated process.

Structures of ascorbic acid

( L-ascorbic acid ) It is the reduced form

L-dehydroascorbic acid It is the oxidized form

L-Ascorbic acid

L-ascorbate naturally occurs either attached to a hydrogen ion, forming ascorbic acid, or joined to a metal ion, forming a mineral ascorbate.

L-dehydroascorbic acid

When L-ascorbate carries out its reducing function, it is converted to its oxidized form, L-dehydroascorbic acid .

BIOSYNTHESIS Some lower mammals like rats can synthesize

the vitamin from glucose by the uoronic acid pathway

Man, Monkey and guinea pigs lack the enzymes necessary for the synthesis. Hence the entire requirement must be taken from the diet .

Metabolism It includes : (Distribution, absorption, excretion)

Distribution

Excretion

Absorption

DistributionNormal human blood plasma contains approx.0.6 to 1.5 mg of ascorbic acid per 100mlThe vitamins exist in the body largely in the ‘reduced’ form, with reversible equilibrium with a relatively small amount of ‘’dehydroascorbic acid’’Both forms are physiologically and metabolically active.

Under normal dietary intake n(75 to 100 mg )

Mainly found in retina,Adrenal glands ,pituitaryGlands & thymus.

50 to 75% is converted to inactive

compounds

25 to 50% is excretedIn urine as such

Absorption Ascorbic acid is absorbed in the body by both active

transport and simple diffusion. It is absorbed readily in small intestine, peritoneum

and subcutaneous tissues. With regular intake the absorption rate varies between

70 to 95%. However, the degree of absorption decreases as intake increases. At high intake (1.25 g), fractional human absorption of ascorbic acid may be as low as 33%; at low intake (<200 mg) the absorption rate can reach up to 98%.

Excretion Ascorbate 2 sulphate is urinary excreted form of

ascorbic acid.

Vitamin C is a threshold substance and it is excreted primarily through kidney.

If intake is normal then slight increase in intake above normal will be excreted.

Daily RequirementLife Stage

Recommended Amount

Birth to 6 months 40 mgInfants 7–12 months 50 mgChildren 1–3 years 15 mgChildren 4–8 years 25 mgChildren 9–13 years 45 mgTeens 14–18 years (boys) 75 mgTeens 14–18 years (girls) 65 mgAdults (men) 90 mgAdults (women) 75 mgPregnant teens 80 mgPregnant women 85 mgBreastfeeding teens 115 mgBreastfeeding women 120 mg

METABOLIC ROLE & FUNCTIONS

ROLE IN CELLULAR OXIDATION REDUCTION :

Vitamin c is very sensitive to reversible oxidation, ascorbic acid to dehydroascorbic acid ,suggests that it may be involved in cellular oxidation-reduction process , serving as hydrogen transport agent . ROLE IN FORMATION OF CATECHOLAMINES :Vitamin C is required as a coenzyme with the enzyme dopamine hydroxylase which catalyzes the conversion of dopamine to norepinephrine.

ROLE IN COLLAGEN SYNTHESIS :Hydroxyproline and hydroxylysine are important constituents of mature collagen fibers. Precollagen molecule contain the amino acids proline and lysine they are hydroxylated by corresponding hydroxylases in presence of vitamin C. PROLINE hydroxyproline

LYSINE hydroxylysine

Protocollagen prolinehydroxylase

Vit.C Fe++,Mol.O2

PROTOCOLLAGEN LYSINE HYDROXYLASE

Vit.C,Fe++, mol.O2

ROLE IN FORMATION OF CARNITINE :Formation of carnitine in liver by hydroxylation of gema-butyrobetaine is helped by vitamin C .

ROLE IN ALPHA-OXIDATION OF FA :Vitamin C helps in the action of the enzyme alpha-hydroxylase which catalyzes the alpha-oxidation of long chain F.A to form alpha-OH-FA.

EFFECT ON CHOLESTEROL LEVEL :Relation of ascorbic acid with hypocholesterolaemia in man and guinea pigs has been reported.

FORMATION OF FERRITINAscorbic acid is necessary for the formation of tissues ‘’ferritin’’ .ATP, NAD+, NADP+.

ACTION ON CERTAIN ENZYMES-ACTIVATION/INHIBITION:

VIT.C is capable of both activating and inhibiting different groups of enzymes . e. g arginine and papain are activated, whereas,urease and BETA- amylase from plants is inhibited.

Vitamin C play an important role in the reaction of the body to stress

Vitamin C have also been reported to act as coenzyme for cathepsine and liver stress.

Ascorbic acid in both leucocytes and platelets found to be lowered significantly in women taking oral contraceptive pills.

VIT.C plays important role in electron transport chain.

CAUSESOF DEFICIENCY OF VITAMIN C

ScurvyA disease caused by a deficiency of vitamin C, characterized by swollen bleeding gums and the opening of previously healed wounds, which particularly affected poorly nourished sailors until the end of the 18th century.

Infantile scurvy (Barlow’s disease)In infants between 6 to 12 months of age the diet should be supplemented with vitamin C sources.

Hemorrhagic Tendency:

In ascorbic acid deficiency, collagen is abnormal & the intracellular cement substance is brittle.

So capillaries are fragile, leading to the tendency to bleed even under minor pressures.

Petechial Hemorrhages:

Due to rupture of capillaries, resulting from lack of intracellular substances.

Eccohymoses or even hematoma in severe conditions.

Internal bleeding:In severe cases, hemorrhage may occur in the conjunctiva & retina.

Oral cavity:In severe cases of scurvy, the gums becomes painful, swollen & spongy.

The pulp is separated from the dentine and finally teeth are lost

Wound healing may be delayed.

Bones:In the bones, the deficiency results in the failure of the osteoblasts to form the intracellular substance, osteoid.

Without the normal ground substance, the deposition of bone is arrested.

The bones become weak and fractures easily.

Hemorrhage into joint cavities.

Painful swelling of joints may prevent locomotion of the patient.

Anemia

In vitamin C deficiency , normochromic, normocytic (due to bleeding), megaloblastic (due to reduced erythropoiesis) and microcytic hypochromic anemia (due to impaired iron absorption & impaired haem synthesis) are seen.

Detection of deficiency in man Urine ascorbic acid ‘’saturation’’ test : A test dose of 5mg per l

lb (pound) body wt. if 50% or more is excreted in next 24 hrs. then the individual has no deficiency of VIT. C.

Intradermal test: intradermal injection of 2,6-dichlrophenol and determination of the time for decolourization i.e., reduction of the dye. abnormally long persistence of blue color in cutaneous wheal indicates saturation of ascorbic acid.

Tourniquet test : a sphygmomanometer cuff is applied an is inflated it compresses venous blood .in short time appearance of petechial haemorrhages on the forearm indicates deficiency.

Hypervitaminosis Severe back pain Jaundice Itchy skin (pruritis) Splenomegaly (Tender mass in left upper abdomen) Fever Abdominal pain Dizziness Vomiting Nausea Headache Facial flushing Dental cavities (caries) Decreased urine output

Hypovitaminosis

Fatigue Mood changes Weight loss Joint and muscle ache Bruising Dental conditions Dry hair and skins Infections because of compromised immune

systems

Dietary Sources Oranges Chili papers Red bell pepper Green ball pepper Kale Broccoli Papaya Strawberries Cauliflower Brussels sprouts Pineapple Kiwi Mango

Vitamin C Day April 4TH Vitamin C day commemorating the

discovery of vitamin C in 1932.

Some Brands Of Vitamin C

References https://www.google.com/search?client=opera&q=scurvy&sou

rceid=opera&ie=UTF-8&oe=UTF-8 http://www.slideshare.net/dileepchimani/vitamin-c-power-poi

nt-30632727 http://www.slideserve.com/megan-hinton/vitamin-c http://blog.naturalhealthyconcepts.com/2011/04/06/enough-vi

tamin-c/ https://ods.od.nih.gov/factsheets/VitaminC-Consumer/ http://

www.rightdiagnosis.com/v/vitamin_c_overdose/symptoms.htm#symptom_list

http://www.health.com/health/gallery/0,,20745689,00.html