vitaminb6-Final .Vitamins are non nutrient chemical substance

Vitamins are non nutrient chemical substance

2. Chemistry and Biochemical Role, RDA
and Deficiency symptoms of Vitamin B6

3. The vitamins are natural and essential nutrients, required in
small quantities and play a major role in growth and
development, repair and healing wounds, maintaining healthy
bones and tissues, for the proper functioning of an immune
system, and other biological functions.

4. Pyridoxine (Vitamin B6) - Introduction
•Pyridoxine refers to a group of naturally occurring
pyridine derivatives.
•Gyorgy identified and separated the heat labile
vitamin B6 that cured a scaly dermatitis in rats fed
with purified diets.
•The structure and synthesis of vitamin B6 or
pyridoxine was established in 1939.

5. Pyridoxine (Vitamin B6) - Introduction
➢Vitamin B6 occurs naturally in three forms
namely:
❑ Pyridoxine,
❑ Pyridoxal and
❑ Pyridoxamine (vitamers of B6).

6. Pyridoxine (Vitamin B6) - Chemistry
➢Vitamin B6 compounds are pyridine derivatives.
➢They differ from each other in the structure of a
functional group.
❑ Pyridoxine is a primary alcohol,
❑ Pyridoxal is an aldehyde form while
❑ Pyridoxamine is an amine.

8. Pyridoxine (Vitamin B6) - Chemistry
➢Synthesis of Coenzyme
➢The active form of Vitamin B6 is the coenzyme
pyridoxal phosphate (PLP).
➢ PLP can be synthesised from the three compounds
pyridoxine, pyridoxal and pyridoxamine.
➢B6 is excreted in urine as 4- pyridoxic acid.

10. Pyridoxine (Vitamin B6) - Biochemical
Functions
➢Pyridoxal phosphate (PLP) is closely associated with the
metabolism of aminoacids.
➢Pyridoxal phosphate participates in reactions like:
❑ Transamination,
❑ Decarboxylation,
❑ Deamination,
❑ Transsulfuration,
❑ Condensation, etc.

11. Pyridoxine (Vitamin B6) – Biochemical
Function
I. Transamination:
•Pyridoxal phosphate is involved in the
transamination reaction (by transaminase)
converting aminoacids to keto acids.

12. Pyridoxine (Vitamin B6) – Biochemical
Function
II. Decarboxylation: Some of the α- aminoacids undergo
decarboxylation to form the respective amines.
➢ This is carried out by a group of enzymes called
Decarboxylases which are dependent on PLP.
➢Many biogenic amines with important functions are
synthesised by PLP decarboxylation.
➢E.g. serotonin, catecholamines ( dopamine,
norepinepherine, epinepherine).

13. Pyridoxine (Vitamin B6) – Biochemical
Functions
III. Deamination of hydroxyl group containing
aminoacids requires PLP.
IV. Transulfuration: PLP plays an important role in the
metabolism of sulfur containing aminoacids.
➢Transsulfuration (transfer of sulfur) from homocysteine
to serine occurs in the synthesis of cysteine.

14. Pyridoxine (Vitamin B6) – Biochemical
Functions
IV. Condensation: Pyridoxal phosphate is
required for the synthesis of δ-amino levulinic
acid, the precursor for heme synthesis.

19. Pyridoxine (Vitamin B6) - RDA
➢The requirement of pyridoxine for an adult is
2-2.2 mg/day.
➢ During pregnancy, lactation and old age, an
intake of 2.5 mg/day is recommended.

20. Recommended Dietary Allowance (RDA) for Vitamin B6
Life Stage Age Males (mg/day)
Females (mg/
day)
Infants  0-6 months 0.1 (AI) 0.1 (AI)
Infants  7-12 months  0.3 (AI)  0.3 (AI)
Children  1-3 years  0.5  0.5 
Children 4-8 years  0.6  0.6 
Children  9-13 years  1.0  1.0 
Adolescents  14-18 years  1.3  1.2 
Adults  19-50 years  1.3  1.3 
Adults 
51 years and
older 
1.7  1.5 
Pregnancy  all ages  -  1.9 
Breast-feeding  all ages  -  2.0

22. Pyridoxine (Vitamin B6) – Dietary
Sources
➢ Generally the availability of vitamin B6 is greater than
75% in most foods.
➢ Rich sources: Egg yolk, fish, liver, whole grain, meat.
➢ Good sources: Bananas, Avocados, cabbage, roots and
tubers.
➢Fair sources: Milk, Cheese, and citrus fruits.

25. Pyridoxine (Vitamin B6) – Deficiency
Symptoms
I. Pyridoxine deficiency is associated with neurological symptoms such as:
❑ Depression,
❑ Irritability,
❑ Nervousness and
❑ Mental confusion.
➢ Convulsions and peripheral neuropathy are observed in severe
deficiency.
➢ These symptoms are related to the decreased synthesis of biogenic amines
(serotonin, GABA, norepinephrine and epinepherine).

26. Pyridoxine (Vitamin B6) – Deficiency
Symptoms
II. Severe deficiency leads to Anemia. Symptoms are
fatigue, Giddiness, nausea, insomnia, Anorexia,
palpitation.
III. In pyridoxine deficiency, there is a decrease in the
amount of urinary citrate which aids in the solubility
of oxalates. This may cause the formation of
urinary calculi.