PRESENTATION ON VITAMINS (1).pptx

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MET FACULTY OF
PHARMACY
P R E S E N TAT I O N O N C H E M I S T RY A N D P H Y S I O L O G I C A L S I G N I F I C A N C E
O F V I TA M I N
S U B M I T T E D B Y S U B M I T T E D T O
A N S H I K A B H AT N A G A R D r. M A N D E E P G U P TA
M . P H A R M A F I R S T S E M I S T E R A S S O C I AT E P R O F.
( P H A R M A C E U T I C A L C H E M I S T RY

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INTRODUCTION OF VITAMIN
• The term vitamin refers to an essential dietary factor that is required by an
organism in small amount and whose absence results in deficiency diseases.
• Vitamins are essential because the organism cannot synthesize these
compounds, which is necessary for life.
• Plants and morst micro organism can synthesize these compounds essential
for normal cellular functioning but which have to be supplied in the diet in small
amounts and required for the growth health and well being.
• The deficiency of vitamins causes specific diseases like xerophthalmia,
beriberi, scurvy, rickets etc. However these deficiency diseases can be cured
and prevented by administration of the vitamin rich diet.
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CLASSIFICATION OF VITAMIN
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CHEMISTRY AND BIOLOGICAL SIGNIFICANCE OF VITAMIN A
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• OCCURRENCE: Vitamin A1 is a fat soluble vitamin which occurs free and as esters in
fats , in fish livers and in blood, other sources are carrots, green vegetables, sweet
potatoes, salad in which it is present in the form of carotenes which in vivo are
converted into vitamin A.

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CONTINUE
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• Vitamin A deficiency:
• Night blindness (nyctalopia) is one of the earliest symptoms of vitamin A
deficiency. The individuals have difficulty to is increased. Prolonged deficiency
irreversibly damages a in dim light since the dark adaptation time see number of
visual cells.
• Severe deficiency of vitamin A leads to xerophthalmia. xerophthalmia. This is
characterized and cornea and keratinization of epithelial cells. In certain areas
of by dryness in conjunctiva conjunctiva, white triangular plaques
• Effect of growth: Within A deficiency results in growth retardation due to
impairment in skeletal formation.
• Effect on reproduction: The reproductive system is adversely affected in vitamin
A deficiency Degeneration of germinal epithelium leads to sterility in males.
Termination of pregnancy due to feal death is observed.

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• Hypervitaminosis A
• Excessive consumption of vitamin A leads to toxicity. The symptoms of
hypervitaminosis A include dermatitis (drying and redness of skin), enlargement
of liver, skeletal decalcification, tenderness of long bones, loss of weight,
irritability, loss of hair, joint pains etc. The subjects have constant headache due
to raised intracranial pressure which resembles the symptoms of brain tumor.
Ingestion of high quantities of vitamin A by pregnant women is associated with
the risk of congenital malformations in the developing fetus.
• Properties
• When the vitamin A was isolated originally, it was a yellow oil. But later on it was
as a crystalline solid, M.P. 63 - 64°C It is optically inactive and sensitive to light
and air but is extant to heat. It is destroyed by UV light.

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ESTIMATION OF VITAMIN A
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• 20-25 % Solution of Antimony trichloride in chloroform Added to Solution of Vitamin A in chloroform
Blue colour observed only for 10 sec.
Result express in terms of cod liver oil units

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ISOLATION OF VITAMIN A
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1) Fractional Crystallisation:
Unsaponified portion Dissolved in Methyl alcohol
Chilled at -73° C
When Sterols Crystallise out, Vitamin A obtained by Fractional Distillation in Vacuum
2) Chromatographic adsorption Method:
Unsaponified portion Adsorb on Alumina Followed by Adsorption on calcium Hydroxide
Gives Purest Vitamin A but it suffers losses due to its destruction which occurs due to
arrangement of double bond and its slight oxidation

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CONSTITUTION OF VITAMIN A
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1) Molecular formula: C20H30O
2) Presence of primacy Alcoholic group:
vitamin A, forms an ester with p-nitrobenzoic acid (this ester is not crystallisable), it follows
that vitamin A, contains a hydroxyl group. Moreover, the oxidation of vitamin A, yields an
aldehyde indicating that the hydroxyl group is primary alcoholic one.
3)Presence of five double bonds. When catalytically reduced in the presence of platinum or
aluminium amalgam, vitamin A, reacts with 5 moles of hydrogen forming perhydroretinol
(C20H40O)
4)Presence of B-ionone nucleus. Ozonolysis of vitamin A, yields geronic acid per molecule of the
vitamin. Since the same acid is also obtained by the ozonolysis of the known compounds, ẞ-
ionone and B-carotene, it means that there must be one ẞ-ionone nucleus present in the
vitamin A, because ẞ-ionone also gives geronic acid on oxidation.

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SYNTHESIS OF VITAMIN A (POMMER' S SECOND SYNTHESIS)
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CONTINUE
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BIOCHEMICAL ROLE OF VITAMIN A
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• Vitamin A is necessary for a variety of functions such as vision, proper growth
and differentiation, reproduction and maintenance of epithelial cells. In recent
years, each form of vitamin A has been assigned specific functions.
• Vitamin A and vision : The biochemical function of vitamin A in the process of
vision was first elucidated by George Wald . The events occur in a cyclic
process known as Rhodopsin cycle or wald's visual cycle .
• Rods and cones: The retina of the eye possesses two type of cell- rods and
cones
• Rods are involved in dim light vision whereas cones are responsible for bright
light and colour vision.

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WALD’S VISUAL CYCLE
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CONTINUE
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• Rhodopsin (mol. wt. 35,000) is a conjugated protein present in rods. It contains
11-cis retinal and the protein opsin. The aldehyde group (of retinal) is linked to
e-amino group of lysine (of opsin).
• The primary event in visual cycle, on exposure to light ,is the isomerization of
11-cis-retinal to all trans retinal. This leads to a conformational change in opsin
which is responsible for the generation of nerve impulse. The all-trans-retinal is
immediately isomerized by retinal isomerase (of retinal epithelium) .
• However, this combines with opsin to regenerate rhodopsin and complete the
visual cycle . However, the conversion of all trans-retinal to 11-cis retinal is
incomplete. Therefore, most of the all-trans-retinal is transported to the liver and
converted to all-trans retinol by alcohol dehydrogenase. The all-frans-retinol
undergoes isomerization to 11-cis retinol which is then oxidized to 11-cis retinal
to participate in the visual cycle.

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• Bleaching of rhodopsin: when exposed to light, the colour of rhodopsin changes
from red to yellow , process known as bleaching. Bleaching occurs in a few
milliseconds and many unstable intermediates are formed during this process.
Rhodopsin- Prelumirhodopsin- Lumirhodopsin → Metarhodopsin I-
Metarhodopsin II-Opsin + All-trans retinal
• Colour vision
• Cones are specialized in bright and colour vision. Visual cycle comparable to
that present in rods is also seen in cones. The colour vision is governed by
colour sensitive pigments-porphyropsin (red), Iodopsin (green) and cyanopsin
(blue). All these pigments are retinal-opsin complexes. When bright light Strikes
the retina, one or more of these pigments are bleached, depending on the
particular colour of light.

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VISUAL CASCADE AND cGMP
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CHEMISTRY AND BIOLOGICAL SIGNIFICANCE OF
VITAMIN B COMPLEX
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• This is not one vitamin but a group of water soluble vitamins which are found in
yeast, liver, rice polishings, etc. This group of vitamins includes (i) thiamine (ii)
riboflavin , (iii) pantothenic acid, (iv) nicotinic acid , (v) pyridoxine , (vi) folic acid
(vii) biotin, (viii) cyanocobalamin Other compounds which have definitely been
isolated from the vitamin B complex are
• (i) p-aminobenzoic acid(a growth factor for bacteria), (ii) myoinositol (a growth
factor in animals), (iii) choline, (iv) carnitine (oxidation of fatty acids in certain
insects) and lipoic acid (a growth factor for some micro-organisms).

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VITAMIN B1 (THIAMINE)
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• Introduction. Thiamine contains a pyrimidine ring and a thiazole ring held by a
methylene bridge. Thiamine is the only natural compound with thiazole ring. The
alcohol (OH) group of thiamine is esterified with phosphate (2 moles) to form
the coenzyme, thiamine pyrophosphate (TPP or cocarboxylase). The
pyrophosphate moiety is donated by ATP and the reaction is catalysed by the
enzyme thiamine pyrophosphate transferase.

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CONTINUE
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• Occurrence. It is a water soluble vitamin which occurs abundantly in the outer
coats of the seeds of many plants including the cereal grains like rice, wheat,
etc. In small quantity, it is also found in some animal organs, viz, liver and
kidney. It also occurs in yeast, milk ground nuts, eggs, all green vegetables,
roots, fruits, and dairy products (except butter). In animal tissues and in yeast it
occurs primarily coenzyme thiamine pyrophosphate or cocarboxylase.
• Deficiency symptoms. The deficiency of vitamin B, results in a condition called
beriberi. Beriberi is mostly seen in populations consuming exclusively polished
rice as staple food. The early symptoms of thiamine deficiency are loss of
appetite (anorexia), weakness, constipation, nausea, mental depression,
peripheral neuropathy, irritability etc. Numbness in the legs complaints of 'pins
and needles sensations are reported.
• In adults, two types of beriberi, namely wet beriberi and dry beriberi occur.
Infantile beriberi that differs from adult beriberi is also seen.

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CONTINUE
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• .
(a) Dry beriberi: This takes place in the case of lesser deficiency of thiamine.
In this type of disease, there occurs muscular weakness and loss of weight,
neuritis, pain in the arms and legs and decrease in blood pressure. The
person suffering from dry beriberi responds rapidly to thiamine administration.
(b) Wet beriberi: This takes place in the case of severe deficiency of thiamine.
In this case, the entire nervous system is affected and results in a types of
paralysis, leading to edema and impaired cardiac function.
The symptoms of beriberi are often mixed in which case it is referred to as
mixed beriberi

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ISOLATION OF THIAMINE
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• Vitamin B1 rich material Agitated Acidulated water pH 4.5
Vitamin B1 goes into
the aqueous solution
The solution shaken with fuller’s earth allows to adsorb vit.B1 on Fullers
earth
Eluted with Quinine sulphate releases Vit. B1 and Excess of Quinine is ppt by
Barium hydroxide and Vit.B1 is convert into silver salt by AgNo3 solution.

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CONSTITUTION OF THIAMINE
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• Molecular formula: C12H18Cl2N4OS
• Decomposition product : When hemihydrate of thiamine is treated with a sodium
sulphite solution saturated with sulphur dioxide at room temperature, thiamine
undergoes decomposition quantitatively into two compounds, say, (A) and (B),
containing thiazole ring and pyrimidine ring respectively as follows:

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CONSTITUTION OF COMPOUND A
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• Molecular formula: C6H9NOS
• Presence of tertiary nitrogen atom: Compound A shows basic properties but
does not react with Nitrous acid, it reveals that the nitrogen is in tertiary state.
• Presence of primary Alcoholic group: When compound A is treated with HCl ,
a hydroxy group is replaced by a chlorine atom to yield a chloro-derivative of
compound A. The UV spectrum of the chloro-compound has been found to be
same as that of parent compound A indicates the hydroxy group is a primary
alcoholic group.

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CONSTITUTION OF COMPOUND B
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• Molecular formula: C6H9N3O3S
• Presence of Sulphonic acid:
Compound B Pressure at 200°C Sulphuric acid
Presence of Amino group:
Compound B + Nitrous Acid -N2 gas Shows that it contains one or more
amino group then further analysis of compound B reveals it contain only one
amino group.

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SYNTHESIS OF THIAMINE
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BIOCHEMICAL ROLE OF THIAMINE
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• In animal tissues and yeast, it occurs primarily as the coenzyme
thiamin pyrophosphate or cocarboxylase.
•

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CONTINUE
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• Thiamine pyrophosphate participates as a coenzyme in a-keto acid
dehydrogenases, pyruvic decarboxylase transketolase and phosphoketolase, an
enzyme concerned with the metabolism of pentoses in certain bacteria. For
example
• D-Xylulose-5-P + P1 Phosphoketolase Acetyl-P + Glyceraldehyde-P
• Cocarboxylase
• It should be noted that yeasts can decarboxylate pyruvic acid because they
contain thiamine pyrophosphate (cocarboxylase) and the apoenzyme
(decarboxylase). Animal cells contain thiamine pyrophosphate when the thiamine
supply is adequate, but they lack the apoenzyme, the decarboxylase. That is why
decarboxylation in these cells is carried out as an oxidative decarboxylation.
•

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CONTINUE
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VITAMIN B2 (RIBOFLAVIN)
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Introduction. Since vitamin B2, is chemically related to the yellow water-soluble
pigments known flavins and it was also isolated from milk, it is also known as
lactoflavin.
• Riboflavin contains 6, 7-dimethyl isoalloxazine (a heterocyclic 3 ring structure)
attached to D-ribitol by a nitrogen atom. Ribitol is an open chain form of sugar
ribose with the aldehyde group (CHO) reduced to alcohol (CH2OH)

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CONTINUE
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• Occurrence. Vitamin B2 is widely distributed in plants and animals. It is present
in yeast, vegetables. milk, egg white, liver, kidney, meat, etc. The primary
source of vitamin B2 is plant material, although commercial production by
yeasts and certain micro-organisms is practised The vitamin B2 occurs in
nature almost exclusively as a constituent of the two flavin prosthetic groups,
flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD).
• Deficiency Disease. The symptoms of vitamin B2 deficiency are difficult to
observe in man. Signs such as a dark red tongue, dermatitis, and cheilosis
similar to those of niacin deficiency have been observed. Its deficiency in
human system also reduces growth and causes general weakness.
• Intake of large doses of riboflavin (5-10 mg/day) in humans does not result in
any toxic symptoms.
• Properties. Vitamin B2 is a bright yellow powder which decomposes at -280°C.
It is soluble in water and in ethanol but is insoluble in chloroform and other
organic solvents.

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ISOLATION OF RIBOFLAVIN
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• Material rich in vitamin B2 Agitated Conc. HCl followed by filtration
Filtrate contain Vit. B2
Vit. B2 from filtrate adsorb on Fuller’s earth, treated with water and loses HCl
After this Vit. B2 is eluted by basic solvents like Pyridine-methanol-water
mixture, Ammonia etc. Vit.B2 is ppt from elute as sparingly soluble Thallium
salt.
Separation of riboflavin and riboflavin 5’-Phosphoric acid from Flavin
combined with protein is achieved by dialysis in cellophane tubes at 3°C fir 1
hour.

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CONSTITUTION OF RIBOFLAVIN
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• Molecular formula: C17H20N4O6
• Presence of 4 –OH group:
Silver salt of riboflavin Acetylated tetra-acetylated derivative indicate 4 –
OH group
Oxidation:
Riboflavin Oxidised with lead tetra acetate Formaldehyde
indicate
A primary hydroxyl group is present in an a-position to
a secondary hydroxyl group

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CONTINUE
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• Nature of Nitrogen atom: Riboflavin does not react with nitrous acid ,
this shows that is does not contain free primary amino group.
however alkaline hydrolysis of riboflavin yield urea indicating that it
contain –NH-CO-NH- group.
• Alkaline solution of riboflavin Irradiated Lumilactoflavin (Yield
new compound)

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SYNTHESIS OF RIBOFLAVIN
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BIOCHEMICAL ROLE OF VITAMIN B2
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CONTINUE
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CONTINUE
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CONTINUE
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VITAMIN B12 (CYNOCOBALAMINE)
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• Introduction. Vitamin B12 is the first natural product which contains cobalt.
Vitamin B12 is also own as anti-pernicious anaemia vitamin It is a unique
vitamin, synthesized by only microorganisms and not by animals and plants. It
was the last vitamin to be discovered .
• The structure of vitamin B12 consists of a corrin ring with a central cobalt atom.
The corrin ring is most similar to the tetrapyrrole ring structure found overline in
other porphyrin compounds eg. heme (with Fe) md chlorophyll (with Mg).
• Occurrence: Vitamin B12 is not present in plant kingdom but is found in all
animal tissues especially the liver of ox, sheep, horse, pig, fish, etc. It is also
present in cow dung and urine. It is also synthesised certain micro-organisms

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• Deficiency Disease. It is essential growth factor for many micro-organisms. Its
deficiency in man causes pernicious anaemia which is followed by degradation
of spinal cord. This disease does not arise the to the absence of vitamin B12 in
diet but due to the lack of secretion in stomach called intrinsic factor which is
essential for the assimilation of vitamin B12 The same symptoms also appear in
the case of folic and deficiency. Thus, patients respond to either of the two
vitamins. However, B12 is considered to be more beneficial than folic acid.

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ISOLATION OF VITAMIN B12
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• Isolation is divided into three different steps as follows:
• Preparation of liver extract. After mincing, the liver is boiled with water to
coagulate proteins which are removed by filtration. The filtrate is then made to
treat with different mixtures of water and alcohol repeatedly to precipitate
various impurities. After filtration, the filtrate is made to adsorb on charcoal at a
specific pH. The impurities remain on charcoal whereas the filtrate containing
vitamin B12 passes down. This process is repeated with this filtrate many times
to get partially purified liver extract
• Purification of liver extract. The extract obtained from step (a) is further
purified by employing adsorption and partition chromatography. In the former
case, the extract in water is adsorbed on alumina whereas in the latter case
silica is used as an adsorbent and n-butanol as a solvent.
• Crystallisation. From the purified liver extract obtained from step (b), vitamin
B12 is crystallised by employing different crystallisation procedures

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CONSTITUTION OF VITAMIN B12
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• The structure now accepted requires a formula of C63H84N14PCO14
corresponding to a molecular weight of 1355
• The UV absorption spectrum of an aqueous solution of vitamin B12 exhibits
three maxima at 278, 361 and 550 nm with extinction coefficients of 115, 207
and 63 respectively. The UV spectrum remains unchanged by changing the pH
of the aqueous solution.
• The vitamin B12 is optically active and behaves as a polyacidic base; it forms a
hexaperchlorate.

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CONTINUE
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• Magnetic susceptibility measurements, which indicated the diamagnetic
character of the vitamin B12 resulted in the assignment of the trivalent state to
the cobalt atom. This was further confirmed by polarographic studies.
• Infrared studies revealted the presence of a replaceable cyanide group which is
tightly and co-ordinately bound to the cobalt atom.

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BIOCHEMICAL ROLE OF VITAMIN B12
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• Vitamin B12, which has been found only in animals and microorganisms and
not in plants, occurs as part of a coenzyme known as coenzyme B12.
• The reducing system is complex in that it involves a NADH-flavoprotein-disulfide
(S-S) protein system.
• The reductant, NADH, transfers its electrons via a flavoprotein to the specific
disulfide (S-S) protein to form a dithiol (SH, SH) protein that converts vitamin 12
(Co^ 2+ ) to vitamin B12 (Col+). This reduced form then becomes the substrate
for the alkylation reaction with ATP.

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CONTINUE
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CONTINUE
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VITAMIN C
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• Introduction. Vitamin C is more related to the monosaccharides than other
vitamins, Vitamin C is water soluble versatile vitamin. It plays an important role
in human health and disease. Vitamin C has become the most controversial
vitamin in recent years. This is because of the claims and counter-claims on the
use of vitamin C in mega doses to cure everything from common cold to cancer.
• Occurrence. Vitamin C is widely distributed in both plants and animals. In
plants, it is mainly found in citrous fruits like lemons, oranges, black carrots, etc.
It is also found in green vegetables like Cabbage. beans and tomatoes. In
animals, it occurs in tissues and various glands or organs (e.g., liver, adrenal
glands, thymus, corpus luteum, etc
• Deficiency Disease. The deficiency of vitamin C causes the disease scurvy (fe,
tendency to haemorrhage and structural changes in the cartilage, bone and
teeth) in infants and adults. In severe deficiency, There occurs swelling and
bleeding of gums and teeth become lose.

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CONSTITUTION OF VITAMIN C
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• Molecular formula. C6H3O6
• Presence of keto-enol system.
• (1) Ozonolysis of ascorbic acid takes place without producing fragments,
indicating that it contains one double bond.
• (ii) Ascorbic acid also acts as a strong reducing agent.
• (iii) With ferric chloride solution, ascorbic acid gives violet coloration, indicating
the presence of -OH group in it.
• (iv) With phenylhydrazine, ascorbic acid yields phenyl hydrazone, indicating that
it contains >C-0 group.
• (v) As ascorbic acid does not restore coloration of Schiff's reagent, it does not
contain aldehyde group.
• All the above facts suggest that a keto-enol system is present in ascorbic acid,

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CONTINUE
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• Presence of carboxyl group. Ascorbic acid forms monosodium and
monopotassium derivatives, indicating that it may contain -COOH
group. But ascorbic acid does not give effervescence of CO2 with
sodium bicarbonate solution. Therefore, it should not contain free
carboxyl group.

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ESTIMATION OF VITAMIN C
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SYNTHESIS OF VITAMIN C (HAWORTH AND HIRST SYNTHESIS)
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BIOCHEMICAL ROLE OF VITAMIN C
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CONTINUE
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VITAMIN E
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• Introduction. Vitamin E represents a group of eight compounds which are
collectively called tocopherols. The most biologically active compound is a-
tocopherol whereas ẞ-and y-tocopherols exhibit about half the activity of a-
compound
• Occurrence. It is widely distributed in nature in plant and animal tissues. This
vitamin occurs in wheat germ oil (which contains a-and B-tocopherols), cotton
seed oil (which contains y-tocopherols), soyabean oil (which contains 8-
tocopherol), palm oil and rice. In animals, it occurs mainly in the livers of horses
and cattles and in small amounts in the muscles of heart, kidney, placenta and
egg. There is some evidence that all a-tocopherol is localised in the
mitochondria

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CONTINUE
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• Deficiency Disease. Its deficiency in animals and man results in the following
diseases
• (i) It causes antisterility. Due to this antisterility factor, the vitamin E was called
tocopherol because word tokos (Greek) means childbirth and phero (Greek)
means to bear
• (ii) It causes increase in the number of leucocytes, i.e, WBC of the blood,
causing blood anaemia. (iii) It causes increased excretion of creative and
pentose sugar (ribose) in urine which is primarily due to degeneration of
muscles.
• (iii) It also increases concentration of RNA and DNA in the bone marrow

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ISOLATION OF VITAMIN E
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• Isolation. The oil obtained by pressing dried wheat germs is
saponified by treating it with 20 per cent alcoholic KOH in the
absence of oxygen. The saponified portion is rejected whereas the
unsaponified Portion is worked out which contains sterols and
vitamin E .The former is removed by precipitating with digitonin.
Now the remaining oil when subjected to distillation yields vitamin E
fraction at 200-300°C under 0.1 mm pressure. This method is not
economical due to loss of vitamins.

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CONSTITUTION OF TOCOPHEROL
57
• Molecular formula. C29H50O2
• Nature of the one oxygen atom. One of the oxygen atoms is present as hydroxyl
group since tocopherol forms monoacetate, monoester and mono ether. Further
it was shown by an examination of the UV spectra of a-tocopherol and its
acetate that this hydroxyl group is phenolic in nature.
• Nature of the second oxygen atom. The second oxygen atom is found to be
present as cyclic ether.
• Thermal decomposition of a Tocopherol. When a-tocopherol is heated under
different conditions, Past different products are obtained.

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CONTINUE
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SYNTHESIS OF VITAMIN E (Miller's Synthesis )
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BIOCHEMICAL ROLE OF VITAMIN E
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• Tocopherol in vitro is a strong antioxidant activity.
• The biochemical activity of tocopherol is to protect sensitive mitochondrial
system from irreversible inhibition by lipid peroxidase.

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CONTINUE
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CHEMISTRY AND BIOLOGICAL SIGNIFICANCE OF NIACIN
( VITAMIN B 5 )
62
• Introduction. The term niacin is the official name of the vitamin nicotinic acid.
The biochemically active form of the vitamin niacin is the amide, nicotinamide or
niacinamide. Niacin is pyridine derivative, Structurally, it is pyridine 3-carboxylic
acid. The amide form of niacin is known as niacinamide or nicotinamide.
• Occurrence. Niacin is widely distributed in plant and animal tissues, meat
products like liver, meat and kidney It is also present in yeast, grain cereals,
pulses, groundnut and coffee.
• The coenzyme forms of the nicotinamide are the nicotinamide nucleotide
coenzymes I and II which play a part in many biological oxidations.

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CONTINUE
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• Deficiency Disease. Both nicotinic acid and nicotinamide are
human pellagara-preventing factor. Pellagara is characterised by the
lesions of those parts of the body which are exposed to sunlight.
Their deficiency also causes black tongue in dogs.
• Severe deficiency of both nicotinic acid and nicotinamide causes
disturbances in digestive and nervous systems

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CONSTITUTION OF NICOTINIC ACID
6
4
• Molecular formula : C6H5NO2
• Presence -COOH group:
Nicotinic acid Presence of –COOH Mono-sodium salt + Esters + Acid chloride
• Nature of N-atom:
As nicotinic acid forms addition salts with strong acids like HCl and HBr. This
shows that the nitrogen of nicotinic acid is basic in nature.
• Structure of nicotinic acid.
• Nicotinic acid on decarboxylation with lime yields pyridine. This reaction shows
that nicotinic acid is pyridine monocarboxylic acid. The position of the -COOH
group has been found to be 3 when the physical constants of the three acids
(pyridine-1-, 2-and 3-carboxylic acids) are compared with that of nicotinic acid.
This position has been further confirmed by the oxidation of 3-phenyl pyridine
which is obtained from ẞ-naphthylamine.

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CONTINUE
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SYNTHESIS OF NIACIN
66
• 1) By oxidation of Nicotine:

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CONTINUE
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• 2) From Quinoline:

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BIOCHEMICAL ROLE OF NIACIN
68
• Dietary nicotinamide, niacin and tryptophan (an essential amino acid) contribute
to the synthesis of coenzymes- nicotinamide adenine dinucleotide and
nicotinamide adenine dinucleotide phosphate.
• The coenzymes NAD and NADP are involved in a variety of oxidation reduction
reactions.
• They accept hydride ion (hydrogen atom and one electron) and undergoes
reduction in the pyridine ring. This results in the neutralization of positive
charge.
• The nitrogen atom and the fourth carbon of nicotinamide ring participate in the
reaction.
• While one atom of hydrogen (as hydride ion) from the substrate (AH2) is
accepted by the coenzyme and the other hydrogen ion is released into the
surrounding medium.

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CONTINUE
69

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CONTINUE
70

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CHEMISTRY AND BIOLOGICAL SIGNIFICANCE OF FOLIC
ACID
71
• Introduction. Folic acid consists of three components pteridine ring,
p-amino benzoic acid (PABA) and glutamic acid (1 to 7 residues).
Folic acid mostly has one glutamic acid residue and is known as
pteroyl-glutamic acid (PGA).The active form of folic acid is
tetrahydrofolate .
• It is synthesized from folic acid by the enzyme dihydrofolate
reductase. The reducing equivalents are provided by 2 moles of
NADPH. The hydrogen atoms are present at positions 5, 6, 7 and 8
of THF.

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CONTINUE
72
• Folic acid deficiency : it is the most common vitamin deficiency, observed
primarily in the pregnant women. The lactating women, women on oral
contraceptives and alcoholics are also susceptible to folate deficiency. The folic
acid deficiency may be due to (one or more causes) inadequate dietary intake,
defective absorption, impaired metabolism and increased demand. In the
pregnant women, a decreased absorption and increased clearance of folate is
responsible for the deficiency. Treatment with certain drugs (e.g. methotrexate)
that inhibit dihydrofolate reductase will cause folic acid deficiency.
• Properties. It is a yellow crystalline solid which is sparingly soluble in water. This
is stable in acid solution but is sensitive to sunlight and to high temperature

73
ISOLATION OF FOLIC ACID
73
Acidified liver extract Flow through Column (Activated coconut charcoal)
Latter adsorbs Folic acid elute with Alcoholic ammonia
the elute adsorb on super filterol followed by elution with ethanolic ammonium
hydroxide
Eluted concentrated Solution is ppt as Barium salt and then as phosphotungstate
Esterified compound adsorb over super filterol followed by elution on Acetone. folic
acid is purified by crystallisation and liberated as free acid by treating with NaOH

74
CONSTITUTION OF FOLIC ACID
74
• This was elucidated by Argier et. al., (1946) by carrying out experimentation on
the yeast L. casei factor. The structure of the latter has been found to be similar
to the folic acid obtained from Liver L casei factor with the difference that folic
acid obtained from yeast casei factor contains three molecules of glutamic acid
whereas that obtained from Liver L. casei factor contains only one molecule of
glutamic acid

75
CONTINUE
75
• The constitution of folic acid has been elucidated on the basis of
following facts
A) Alkaline hydrolysis of the yeast L. casei factor in anaerobic
condition yields two molecules of D-glutamic acid and the DL-form
of L. casei factor.
• On the other hand, alkaline hydrolysis of the yeast L. casei factor in
aerobic condition yields two substances:
• (1) an aromatic amine and (II) C7H5N5O3

76
CONTINUE
76
2) Structure of compound A (Aromatic amine)
• On hydrolysis, it yields one mole of p-aminobenzoic acid and three
moles of glutamic acid.
•

77
CONTINUE
77
• 3) Structure of compound B:
• Molecular formula: C7H5N5O3
• By the usual tests, it is shown that this compound B contains one
carboxyl, one amino and one enolic hydroxyl group.

78
SYNTHESIS OF FOLIC ACID
78

79
CONTINUE
79

80
BIOCHEMICAL ROLE OF FOLIC ACID
80
• Although folic acid is the vitamin, its reduction products are the
actual coenzyme forms. As enzyme, L-folate reductase, reduces
folic acid to dihydrofolic acid .

81
CONTINUE
81

82
CONTINUE
82

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