Water soluble vitamins

1. NUTRITIONAL
BIOCHEMISTRY
PRESENTED BY
SOWMIYA G

2. Vitamin B3-Niacin
• This vitamin also known as
pellagra preventive factor.
• Vitamin B3 also called as Nicotinic
acid.

3. DISCOVERY
• Joseph Goldberger In 1920.

4. Properties
Niacin is an odorless white, crystalline
substance.
It is readily soluble in water.
It is resistant to heat, oxidation and alkalis.
It is one of the stable vitamin.
Cooking causes little actual destruction of
niacin, but a considerable amount may be
lost in the cooking water.

5. STRUCTURE

6. Function in the body
• Niacin is important for proper blood circulation.
• For healthy functioning of nervous system.
• It maintains the normal functions of GI tract.
• It is essential for the metabolism of proteins and
carbohydrates.
• It helps to maintain a healthy skin.
• It helps to increase the flow of blood to the
peripheral capillary system.

7. Healing and therapeutic properties
Pellagra
• Administration of small
amounts of up to 10mg
or 10000 mcg per day
is sufficient to cure
endemic pellagra.

8. High blood pressure
Niacin has been
used as vasodilator to
dilate blood vessels
and to correct blood
pressure changes.

9. Heart-Related Disorder
Niacin has
been found to
provide relief in
angina pectoris.

10. High Blood Cholesterol
Niacin has
proved to have a
remarkable effect
in reducing high
blood
Cholesterol.

11. Diarrhoea
The administration of
niacin in therapeutic
doses along with other
B vitamins can cure
diarrhoea.

12. Recommended Daily Allowance (RDA)
•Normal requirement is 20
mg/day. During lactation,
additional 5 mg are
required.

13. Co-enzyme forms of niacin
• Co-enzyme forms of niacin are
• Nicotinamide adenine dinucloetide
(NAD+)
• Nicotinamide adenine dinucloetide
phosphate (NADP+)

14. NAD+ Dependent Enzymes
1. Lactate dehydrogenase (lactate → pyruvate)
2. Glyceraldehyde-3-phosphate dehydrogenase
(glyceraldehyde-3-phosphate →1, 3-
bisphosphoglycerate)
3. Pyruvate dehydrogenase (pyruvate → acetyl
CoA)
4. Alpha ketoglutarate dehydrogenase
(alpha ketoglutarate → succinyl CoA)

15. 5. Beta hydroxy acyl CoA dehydrogenase
betahydroxy acyl CoA → beta keto acyl
CoA
6. Glutamate dehydrogenase
(Glutamate → alpha keto glutarate)

16. VITAMIN B6
• Vitamin B6 also called pyridoxine is a water
soluble
• vitamin that is naturally present in many
foods, added to others, and available as a
dietary supplement.
• Your body needs it for regular nervous
system function, production of normal red
blood cells and protein metabolism

17. STRUCTURE

18. FOOD SOURCES
Vitamin B6 is found in:
• Avocado
• Banana
• Legumes (dried beans)
• Meat
• Nuts
• Poultry
• Whole grains

19. Co-enzyme Form
• Vitamin B6 is the term applied to a family of
3 related pyridine derivatives; pyridoxine
(alcohol), pyridoxal (aldehyde) and
pyridoxamine.
• Active form of pyridoxine is pyridoxal
phosphate (PLP)
• It is synthesized by pyridoxal kinase, utilizing
ATP.

20. MODE OF ACTION
1. Transamination
• These reactions are catalyzed by amino
transferases(transaminases) which employ
PLP as the co-enzyme
For example:
Alanine + Alpha keto glutarate → Pyruvate +
Glutamic acid (Enzyme
Alanine
transaminase).

21. 2. Decarboxylation
• All decarboxylation reactions of amino acids require
PLP as co-enzyme. A few examples are given
below:
• Histidine → histamine
which is the mediator of allergy and anaphylaxis.
• Cysteine → taurine
• Serine → ethanol amine

22. 3. Sulfur Containing Amino Acids
• PLP plays an important role in
methionine and cysteine metabolism.

23. FUNCTIONS
• Vitamin B6 helps the body to:
• Make antibodies. Antibodies are needed to fight
many diseases.
• Maintain normal nerve function
• Make hemoglobin. Hemoglobin carries oxygen in
the red blood cells to the tissues. A vitamin B6
deficiency can cause a form of anemia.
• Break down proteins. The more protein you eat, the
more vitamin B6 you need.
• Keep blood sugar (glucose) in normal ranges.

24. Biotin
• Biotin is formerly known as anti-egg white
injury factor or vitamin H
• It is water soluble sulfur containing B-
complex
vitamin
• Biotin mainly participates in the
carboxylation reactions.
• Biocytin is the coenzyme form of Biotin

25. STRUCTURE

26. Dietary Sources
• Biotin is found in these food sources:
• egg yolk
• organ meat
• poultry
• milk & cheese
• whole grains, rice -salmon

27. • Biotin is required for carboxylation
reactions (CO2fixation reaction)
• Biotin is required for the enzymes
• Pyruvate carboxylase
• Acetyl CoA carboxylase
• Propionyl carboxylase
• β - Methyl crotonyl CoA carboxylase

28. MODE OF ACTION
Biotin is the coenzyme for 4 carboxylases.
1.Acetyl coenzyme A carboxylase:
found in the mitochondria; catalyzes the
carboxylation of Acetyl CoA to Malonyl CoA.
2.Pyruvate carboxylase:
found in the mitochondria; catalyzes the
carboxylation of pyruvate to form
oxaloacetate.

29. 3.Methylcrotonyl-CoA carboxylase:
found in the mitochondria; involved in
the metabolism of Lleucine.
4.Propionyl-CoA carboxylase:
involved in the metabolism of L-
isoleucine, L-valine, L-threonine, and L-
methionine.