VITAMIN B3
GUL MUNEER
Niacin
Niacinamide 0R Nicotinamide
Vitamin P OR PP (pellagra preventive)
Pellagra preventive factor
Anti black tongue factor
Nicotinic acid
Vitamin G (after Goldberger’s death, vitamin B3 was some times called in his honor)
Structure of Vitamin B3
Function of Vitamin B3
DISCOVERY of Vitamin B3
PROPERTIES of Vitamin B3
Nicotinic Acid (Plant form)
CHEMISTRY of Vitamin B3
Sources of Vitamin B3
RECOMMENDED DAILY ALLOWANCE (RDA) of Vitamin B3
BIOCHEMICAL FUNCTIONS of Vitamin B3
Digestion and Absorption of Dietary Niacin
Metabolism of B-3
Deficiency of B3
4. NAMES 0F VITAMIN B3
Niacin
Niacinamide 0R Nicotinamide
Vitamin P OR PP (pellagra
preventive)
Pellagra preventive factor
Anti black tongue factor
Nicotinic acid
Vitamin G (after Goldberger’s
death, vitamin B3 was some times
called in his honor)
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6. PROPERTIES
Niacin is a white crystalline
substance. It is soluble in water &
ethyl alcohol but is less soluble in
ether & benzene. It is stable in air &
heat. Nicotinamide, when pure,
occurs as white needle like crystals.
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9. CHEMISTRY
Precursor : Dietary tryptophan
The coenzymes of Niacin (NAD⁺ & NADP⁺)
can be synthesized by the essential amino
acid tryptophan.
The term “Niacin” is used for Nicotinic acid.
The amide form of Niacin is known as
niacinamide or nicotinamide.
The conversion of Niacin to niacinamide
takes place in the kidney, brain slices and
liver slices.
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10. The conversion of tryptophan to nicotinic
acid in the body takes place through a
series of intermediate steps, which are
represented below:
Tryptophan → Kynurenine → 3hydroxykynurenine → 3hydroxyanthranilic acid → …… →
Quinolinic acid → Nicotinic acid
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11. Dietary nicotinamide, niacin and tryptophan
contribute to the synthesis of the
coenzymes NAD⁺ and NADP⁺.
Niacin undergoes a series of reactions to
produce NAD⁺ and NADP⁺.
60mgs tryptophan=1mg of niacin for the
synthesis of coenzymes.
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13. OCCURRENCE
Yeast (most abundantly)
Liver
Salmon
Red meat
Poultry
Vegetables & fruits (poor)
whole grains
Pulses & peanuts
Note: Milk & eggs contain very little
or no Niacin, are good pellagrapreventive foods because of their
high content of Tryptophan.
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17. BIOCHEMICAL FUNCTIONS
The coenzymes NAD⁺ and NADP⁺ are involved
in a variety of “oxidation-reduction reactions”.
A large number of enzymes belonging to the
class “oxidoreductase” are dependent on NAD⁺ or
NADP⁺.
NAD⁺ and NADP⁺ participate in almost all the
metabolisms (carbohydrate, lipid, protein etc).
Involved in electron transport chain to generate
ATP.
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18. Pyruvate + CoA + NAD+ ------> CO2 + acetyl-CoA + NADH + H+
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19. Functions of Niacin
NAD and NADP participates in 200+ reactions in the
body. 2 NAD+
2NADH + H+
Glucose
Pyruvate
NAD+
Pyruvate
NAD+
NADH + H+
Lactate
NADH + H+
Isocitrate
NAD+
Alpha-ketogluterate
NAD+
NADH + H+
Malate
Electron transport chain
Alpha-ketogluterate
NADH + H+
Succinyl CoA
Citric Acid
Cycle
Oxaloacetate
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20. Digestion and Absorption of Dietary
Niacin
Coenzyme form in food
hydrolysis in small intestine to free
vitamin
absorbed in duodenum
nicotinic acid protein bound in corn
requires alkali treatment (lime) to
release niacin
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21. Metabolism of B-3
Conversion of free vitamin to
coenzyme in all cells
No storage
Excesses metabolized in liver to
variety of chemicals
Metabolites excreted in urine
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22. Assessment of B3 Status
Urinary excretion of niacin
metabolites
N-methyl nicotinamide
2-pyridone
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23. Deficiency of B3
Pellagra
commonly
1.
referred to as 3 Ds
Dermatitis
Inflammation
2.
Dementia
confused,
3.
of skin
disoriented
Diarrhea
irritation/inflammation
of mucous membranes
4th D
− if not treated may lead to Death
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26. Dermatitis of skin
Inflammation
Found in the areas of the skin exposed to sun
light (neck, dorsal part of feet, ankle, face).
Diarrhea
Increased frequency and
fluidity of the stools, often with
blood and mucus. (loose stools)
Dementia
Degeneration of nervous
tissue (weakness of mind)
Symptoms include:
Anxiety (fear and worry)
Irritability (respond or
reaction to stimulus)
Poor memory
Insomnia (sleeplessness)
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