2. • Vitamin C (ascorbic acid)
• It is a six carbon sugar derivative and a good water soluble
antioxidant
• Easily destroyed by heat, alkali
• 70% of Vit-C is lost by cooking. The structural formula
closely resembles that of monosaccharide since it obtain
from Glucose
• It has strong reducing property
• Active Form
• Biologically Active forms of vit.C are L-ascorbic acid and
• dehydroascorbic acid
• Inactive form is D- ascorbic acid
• Oxidation of ascorbic acid is rapid in presence of copper.
• Hence, vitamin C becomes inactive if the foods are prepare
• in copper vessel
3. Chemistry
it is hexose derivative and structure is closely resemble to
monosaccharide
It is absorbed in distal portion of small intestine
4. Biosynthesis:
• Most animals and plants can synthesize ascorbic acid
from glucose.
• Man, higher primates, guinea pigs and bats are the only
species which cannot synthesize ascorbic acid due to lack
of glucono lactone oxidase which essential for synthesis of
ascorbic acid. Therefore, it should be supplied in the diet.
• Vit. C is rapidly absorbed from intestine and since it is
water soluble,excreted through urine
• It is a strong reducing agent and reduces Benedict’s reagent
• Ascorbic acid levels varies between 0.4 to 1.5mg/100ml
plasma. A low level in blood is noted in women taking
contraceptive pills and also in chronic alcoholics.
• Very high concentration of Vit C is observed locally in
healing wounds. Vitamin C is essential for wound healing.
5. Oxidation of Vit. C
Vitamin C is oxidized (removal of 2 electrons and 2 protons) to
dehydroascorbate
Ascorbic acid
Oxidation
Dehydro ascorbic acid
Oxidation
Oxalic acid
6. Biochemical function:
• Involve in reversible oxidation reduction reaction (Electron
Transport Chain(ETC) in cells
• Involve in collagen formation: it act as coenzyme in hydroxylation
of proline and lysine leads to form hydroxy proline and hydroxy
lysine those which are essential for the synthesis of collegen
• Involve in tryptophan metabolism where serotonin synthesis which
regulate nerve impulses and regulate sleep, behavior and BP
• Help in bone formation
• Vit .c essential for the conversion ferric form of iron to ferrous
form of iron viz.. It enhance iron absorption
• It is also essential for reconversion of methemoglobin to Hb
• It is also essential for conversion of Hb to bile pigments
7. • it also essential for in tyrosine metabolism
• It also involved in the synthesis of tetra hydro folate(TH4) which
is active form of vitamin folic acid
• It also involved in the synthesis of peptide hormones
• Also involved in corticosteroid hormone synthesis
• It is a strong anti oxidant so it spares Vit A, E and some B
complex vitamins from oxidation
• It enhances the synthesis of immunoglobins and increase the
phagocytic action of leucocyte
• Vit.C reduce the risk of cataract formation
• As antioxidant, reduce the risk of cancer, cataract and coronary
heart disease
• Neurotransmitter metabolism
• Carnitine synthesis
8. • Dietary source: Amla, guava,lime,lemon,green leafy vegetables,
tomatoes , potatoes
• Poor source: milk
• Requirement( RDA ): 60 - 75 mg per day in normal adults
100 mg per day in pregnancy, lactation,and
aged people.
DEFICIENCY MANIFESTATIONS OF VITAMIN C
Vitamin C intakes < 10 mg/d result in scurvy
Scurvey: the deficiency of vit.C results scurvy. The disease is
characterized by spongy and sore gum, loose teeth, anemia,
swollen joints, fragile blood vessels, delayed wound healing,
sluggish(improper) hormonal functions, haemorrhage,
osteoporosis etc.., most of these symptoms are related to
impairment in the synthesis of collagen or impairment
antioxidant property of vit.C
10. Gum changes in infant scurvy:
Gums in scurvy: Very advanced gum lesions in scurvy
11. • 18g/day prevent and cure common cold(said by Linus Puling) but
fact is vit c reduce the severity of common cold not cure. but
recently, consumption of excess of vit.C reduce the severity
• Infantile scurvy( Barlow’s disease)
• Haemorrhagic tendency
• abnormal collagen
• Internal Haemorrhage
• Oral cavity
• Bones become weak
• Anemia- Microcytic, hypo chromic anemia. Reason for anemia
may be: loss of blood by hemorrhage, decreased iron absorption,
decreased tetrahydro folate and accumulation of met HB
Hypervitaminosis: excess amount is not found to be toxic but
dehydro ascorbic acid(Oxalic acid) found to toxic lead to kidney
stone
12.
13. Vitamin like compounds
1. Choline ( actively involve in one C metabolism)
2. Inositol(
3. Lipoic acid ( act along with B1)
4. Para amino benzoic acid (constituent of B9)
5. Bio flavonoids(act like vit C)
