Upload
kuzhandai-velu
View
232
Download
1
Embed Size (px)
Citation preview
7/30/2019 Pyridoxine(Vitamin b6)
1/16
7/30/2019 Pyridoxine(Vitamin b6)
2/16
Vitamins
may regarded as organic compound required in our diet insmall amount to perform specific biological functions for
normal maintenance of optimum growth and health of the
organism
VITAMINS
WATER
SOLUBLE
NON B-COMPLEX
1.VITAMIN C
B COMPLEX
1.THIAMINE(B1)
2.RIBOFLAVIN(B2)
3.NIACIN(B3)
4.PYRIDOXINE(B6)
5.BIOTIN(B7)
6. PANTOTHENIC ACID(B5)
FAT
SOLUBLE
1.VITAMIN A
2.VITAMIN D
3.VITAMIN E
4.VITAMIN K
7/30/2019 Pyridoxine(Vitamin b6)
3/16
PYRIDOXINE(VITAMIN B6)
Vitamin B6 is used to collectivelyrepresent the three compounds
namelya) Pyridoxine
b) Pyridoxal
c) pyridoxamine
7/30/2019 Pyridoxine(Vitamin b6)
4/16
CHEMISTRY
Vitamin B6 compounds are Pyridinederivatives.
They differ from each other in structure of a
functional group attached to 4th
carbon in thepyridine ring.
PYRIDOXINE-Primary alcohol
PYRIDOXAL- aldehyde PYRIDOXAMINE-amine
7/30/2019 Pyridoxine(Vitamin b6)
5/16
PYRIDOXINE-Primary alcohol
PYRIDOXAL- aldehyde
PYRIDOXAMINE-amine
7/30/2019 Pyridoxine(Vitamin b6)
6/16
SYNTHESIS OF COENZYME
The active form of vitamin B6 is the coenzyme
PYRIDOXAL PHOSPHATE(PLP).
PLP can be synthesized by three compounds
pyridoxine, pyridoxal and pyridoxamine.
B6 is excreted in urine as 4-pyridoxic acid.
7/30/2019 Pyridoxine(Vitamin b6)
7/16
ATP
ADP
KINASE
ATP
ADP
KINASE
-O-P
OO
4-Pyridoxic acidpyridoxine
7/30/2019 Pyridoxine(Vitamin b6)
8/16
BIOCHEMICAL FUNCTIONS
PLP, the coenzyme of vitamin B6
is found attached to the -aminogroup of lysine in the enzyme.
PLP is closely associated with themetabolism of amino acids.
The synthesis of products such asserotonin, histamine, niacincoenzyme from the amino acids isdependent on pyridoxine.
Pyridoxal phosphate participatesin reactions like transamination,decarboxylation, deamination,transsulfuration, condensation
etc.
7/30/2019 Pyridoxine(Vitamin b6)
9/16
TRANSAMINATION Pyridoxal phosphate is involved in the
transamination reaction (bytransaminase)converting amino acids to keto
acids.
DECARBOXYLATION Some of the -amino acids undergo
decarboxylation to form the respective amines.
This is carried out by a group of enzyme calleddecarboxylases which dependent on PLP.
Many biogenic amines with important function
are synthesized by PLP decarboxylation.
7/30/2019 Pyridoxine(Vitamin b6)
10/16
a)SEROTONIN
Serotonin helps in nerve impulse transmission
(neurotransmitter).
It regulates sleep, behaviour, blood pressure etc.
tryptophan5-Hydroxytryptophan5-hydroxytryptamineco2
PLP
7/30/2019 Pyridoxine(Vitamin b6)
11/16
b) catecholamine
Catecholamines are involved in metabolic and
nervous regulation.
TyrosineDOPAdopamine norepinephrine epinephrine
co2
PLP
7/30/2019 Pyridoxine(Vitamin b6)
12/16
3.Pyridoxal phosphate is required for thesynthesis of-amino levulinic acid, the precursor
for heme synthesisGlycine
-amino--
Succinyl coA
4.PLP plays an important role in the metabolismof sulfur containing amino acids.
Transsulfuration (transfer of sulfur) fromhomocysteine to serine occurs in the synthesisof cysteine.
Levulinic
acid (ALA)
HemeALA synthase
PLP
7/30/2019 Pyridoxine(Vitamin b6)
13/16
5. Deamination
Deamination of hydroxyl group containing
amino acid requires PLP.
SerineDehydratase
PLP
Pyruvate +NH3
ThreonineDehydratase
PLP- Ketobutyrate +NH3
6.SERINESerine is synthesized from glycine by a PLP
dependent enzyme hydroxymethyltransferase.
R d d di
7/30/2019 Pyridoxine(Vitamin b6)
14/16
Recommended dietary
allowance(RDA)
The requirement of pyridoxine
for an adult is 2-2.2 mg/day .During pregnancy, lactation
and old age , an intake of
2.5mg/day is recommended.
DIETARY SOURCES
Animal sources such as eggyolk, fish , milk , meat are richin B6.
Vegetable sources wheat,corn, cabbage, roots and
tubers.
7/30/2019 Pyridoxine(Vitamin b6)
15/16
Deficiency symptoms
It is associated with neurological symptomssuch as depression , irritability , nervousnes
and mental confusion.
Severe deficiency: The symptoms are related to synthesis of biogenic amines(serine, nor-
epinephrine and epinephrine). Demyelination ofneurons is also observed in vitamin B6 deficiency.
Pyridoxine antagonists: isoniazid,
deoxypridoxine and methoxy pyridoxine are
antagonists of B6.
Irritability
Nervousness Mentalconfusion
Depression
7/30/2019 Pyridoxine(Vitamin b6)
16/16
THANK
YOU