Vitamin B2 (Riboflavin) is essential for normal growth and nutrition. It plays a key role in energy metabolism and processing amino acids and fats. Riboflavin has a molecular formula of C17H20N4O6 and contains 4 hydroxyl groups. Its structure consists of a 6,7-dimethyl-isoalloxazine ring system attached to a ribitoyal sugar alcohol group. Vitamin B12 (Cyanocobalamin) is the first natural compound containing cobalt. It contains a corrin ring structure resembling the tetrapyrrole ring of porphyrins, with a single cobalt atom in the center bonded to 4 nitrogen atoms. It supports

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VITAMINS

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Definition of vitamin
Any of a group of organic compounds which are essential for
normal growth and nutrition and are required in small quantities in
the diet because they cannot be synthesized by body

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Chemistry and physiological
significance of vitamins

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Vitamin B2 (Riboflavin)
• Isolated from milk- Lactoflavin
• 1st B-complex vitamin isolated in pure state
• Structure determined by Paul Karrer
• Present in yeast, liver, kidnay, milk, egg white etc
• Deficiency Disease- cheilosis

5. 5 CONSTITUTION:
1. Molecular Formula: From analytical data C17H20N4O6
2. Presence of 4 –OH group: When silve salt of riboflavin is acetylated, it forms
an tetra acetyl derivative
3. Oxidation: On oxidation with lead tetraacetate, yields formaldehyde- indicates
primary –OH group in an α-position to the secondary –OH group
4. Nature of N atom: Alkaline hydrolysis of riboflavin yields urea- indicates
presence of –NH-CO-NH-group
5. When alkaline solution lumilactoflavin
Acid or neutral solution lumichrome
C13H12N4O2
C17H20N4O6
C12H10N4O2

6. 6 6. STRUCTURE OF LUMILACTOFLAVIN:
a. Molecular formula: C13H12N4O2
b. Photolysis reaction of riboflavin:
C17H20N4O6 C13H12N4O2 + C4H8O4
c. It can neither be acetylated nor oxidised by lead tetra acetate
therefore C4 fragment is a tetrahydroxy butyl side chain
R-CHOH-CHOH-CHOH-CH2OH
d. Alkaline hydrolysis yields urea and amino carboxylic acid (1)
C13H12N4O2 + H2O C12H12N2O3 + CO(NH2)2

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STRUCTURE OF LUMICHROME:
When neutral solution of lactoflavin exposed to light, yields lumichrome
STRUCTURE OF RIBOFLAVIN:
• Structure of riboflavin consist of 6,7-dimethyl-
isoalloxazine (heterocyclic three ring system) to
which sugar alcohol i.e ribitoyal group is attached at
9th position
Synthesis

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• These flavin enzymes takes part in the various oxidation-reduction
reactions
• It aids in the metabolism your fats, carbohydrates, protein and
ketone bodies
• It is also important for your energy metabolism
• Riboflavin is an essential nutrient in human nutrition and plays a
key role in the production of energy
• It is needed to process amino acids and fats and also help to convert
carbohydrates into fuel the body runs on
• Under some conditions, vitamin B2 can act as an antioxident
Physiological significance of vitamin B2

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Vitamin B12 (Cyanocobalamin)
• 1st natural compound containing cobalt
• Water soluble, deep red, tasteless
• Stable at neutral ph

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Chemistry of Vitamin B12

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• There are many closely related compounds having B12 activity. All are
cobalamins contain corrin ring which resembles the tetrapyrrole ring
structure of porphyrins
• Single cobalt atom having one positive charge is present in the centre of
this ring
• The cobalt atom is attached to all 4 N atoms of corrin ring
• Similarly Fe++ is attached to 5, 6-dimethyl benzimidazole ribose which is
attach to the side chain of ring iv through phosphate and aminopropanol
• +ve charge on cobalt atom is balanced by several group which gives rise
to more than one type of vitamin B12 are as follows with characteristic
groups attached to cobalt atom
B12 : Cyanocobalamin : CN
B12-a : Hydroxocobalamin : OH
B12-b : Aquocobalamin : H2O
B12-c : Nitrocobalamin : NO2
Synthesis

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Physiological significance of vitamin B12
1. Supports energy : Without it, your cells get hungry and you feel weak, tired
2. Protects the heart : homocysteine protein roam through the blood and damages
your arteries leading inflammation and heart disease. Vitamin B12 removes
dangerous protein homocysteine from the blood
3. For bones : Studies have found patient with ostioporosis having higher level of
homocysteine and low level of vitamin B12
4. Prevent nerve damage
5. Protects brain health : Alzeimers patient was found to have very low level of B12
6. Keeps you looking and feeling healthy : vitamin B12 supports DNA health
thereby keeping cells younger

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Vitamin C
• also known as ascorbic acid, an water souble vitamin
• It easily destroyed by heat, alkali and on storage
• In the process of cooking 70% of vitamin C is lost
• Use of vitamin C in mega doses to cure everything from
common cold to cancer
Vitamin C

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Chemistry of Vitamin C
1. It has strongly reducing property
2. It is a heterocyclic furan-2-one derivative
3. Vitanin C exist in two forms
• L-ascorbic acid (reduced form)
• L-dehydro ascorbic acid (oxidised form)
oxidised form reduced form

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4. Keto-enol system is present in ascorbic acid

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5. There is a Presence of carboxyl group
6. Ascorbic acid contains two enolic hydroxyl groups, total
four hydroxyl groups are present in ascobic acid
Synthesis
Physiological significance of vitamin C
1. Ascorbic acid performs numerous physiological functions in the human
body
• The synthesis of collagen and neurotransmitter
• The synthesis and catabolism of tyrosine
• The metabolism of microsome
2. It is an antioxident
3. Vitamin C is natural antihistamine
4. The absence of vitamin C in the human diet gives rise to scurvy

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Vitamin B9 (Folic acid)
• A synthetic form of folic acid is used in dietary supliments
• Folic acid defficiency is a known cause of anemia in adults and childrens

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Chemistry of Vitamin B9
Folic acid mainly consist of three components
• Pteridine ring
• PABA
• Glutamic acid residue
hence it is known as pteroyl-glutamic acid
Synthesis

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Physiological significance of vitamin C

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Vitamin B3 (Niacin)
• It is nicotinic acid
• Biochemically active form of niacin is the amide, nicotinamide or niacinamide
• Its deficiency causes pellagra, rough skin

21. 21 1. The conversion of niacin to niacinamide takes place in the kidney, brain
slices and liver slices
2. There is a presence of –COOH group
Nicotinic acid forms mono-sodium salts, ester and acid chloride which indicates
presence of –COOH group
3. Nature of N-atom
Nicotinic acid forms salt with strong acids, this shows that N of nicotinic acid is
basic in nature
Structure of nicotinic acid

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4. Nicotinic acid on decarboxylation with lime yields pyridine and –COOH
group is present at 3rd position
5. Synthesis
By oxidation of nicotine:
[O]
HNO3

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Physiological significance of vitamin C

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