pantothenic acid -

7/29/2019 Pantothenic Acid -

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Panto then ic ac id


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Historical Background

VitB5.

Pantothenic acid. Pantothenate.

1st

discovered at 1919.


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Chemical structure Formula C9H11O5N.Amide between pantoic acid and B-alanine

pantoic acid -alanine


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Characterize by:

Water soluble vitamin.

Appearance: yellow colour, viscous oil.

Un stable to heat, alkali and acid.

Hydrolytic cleavage to:B-alanine and 2-4dihydroxy 3,3 dimethyl

butyrate


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Has two active forms in the

body:

Coenzyme A:

Coenzyme adapted

from cystiene

,pantothenate and

adenosine

triphosphate

Acyl carrier protein:

Its small negatively

charge alpha helical

protein with high

degree of structural

and amino acid

similarity.


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Active forms:

Coenzyme A


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Active forms:

Acyl carrier protein


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VitB5 Sources

Pantosmeans everywhere


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Pharmacokinetics:

In foods, most pantothenic acid is in the form of :CoA oracyl carrier protein (ACP).

For the intestinal cells to absorb this vitamin,

it must be converted into free pantothenic acid.

Within the lumen of the intestine, CoA and ACPare

Hydrolyzed into 4'-phosphopantetheine.

This then dephosphorylated into pantetheine

Pantetheinase, an intestinal enzyme, thenhydrolyzes pantetheine into free pantothenic acid.
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Absorption:

The free pantpthenic acid then absorbedby

either:

- active transport (Na dependant).

- passive transport.

According to the concentration.


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Transport:

Carried in the plasma and erythrocyte.

Enter erythrocyte through passive diffusion.

Distributed to different tissues(brain, heart,kidney, liver).

Enter the cell through Na co transport.

Converted again to the tissue form :

CO enzyme A.


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Metabolism

The synthesis of CoA from pantothenate isregulated primarily by pantothenate kinase, an

enzyme that is inhibited by the pathway end

products, CoA and acyl CoA.

Thus CoA production does not reflect the amount

of available pantothenate


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Coenzyme A synthesisPantothenate

pantothenate kinase

4-phosphopantothenate Cyestiene

ppc synthetase

4-phospho -N-pantothenyl cystiene

ppc decarboxylase4- phosphopantetheine

pp Adenyl transferase

Desphosho coA


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Co A: synthesis

1\ Pantothenate is phosphorylated to 4'-phosphopantothenate.

2\ A cysteine is added to 4'-phosphopantothenate

to form 4'-phospho-N-pantothenoylcysteine (PPC).

3\ PPC is decarboxylated to 4phosphopantotheine.

4\ 4'-phosphopantotheine is adenylylated to formdephospho-CoA.

5\ Finally, dephospho-CoA is phosphorylated usingATP to coenzyme A.


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Synthesized from Apo ACP protien

andCo enzyme A


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Excretion:

Excreted in the urine as free pantothenic acid or 4phosphopantethenate.

In the kidney pantothenic acid either:

Reabsorped.

Tubular secretion.

Amount excreted reflect the dietary intake.

Biomarkers detected by radioimmunoassay.


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Function of Vit B5

Metabolic functions.

Other roles.


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Metabolic

function:


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Format ion

o f acetyl

co A.


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Co A : Funct ions

Citric acid cycle: acetyl residues (in the form ofacetyl Co A) are catabolised.

Fatty acid synthesis & oxidation: fatty acids are

both synthesized from and oxidized to acetyl Co

A.

Cholesterol synthesis: Acetyl Co A is the sourceof all carbon atoms in cholesterol.


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Co A : Funct ions

Biosynthesis of acetylcholine:

choline + acetyl Co A cholineacetyltransferaseAcetylcholine + Co A.

Acetylation reactions: e.g. drugs, post-

translational modification of some proteins.


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In mammals the fatty acid synthase

system is a multienzyme polypeptide

complex.

ACP is part of that complex.

ACP: Funct ion


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Other roles:

Pantothenic acid enhance red blood cellproduction and maintain normal haemoglobin

level

Enhance the immune system through regulating

stress hormones

Maintain the heart healthy through :

lower the cholesterol level

maintain normal blood pressure Reduce the acne


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Recent research:

Diabetic ulceration

Diabetic peripheral polyneuropathy

Testicular torsion

Rheumatoid arthritis

Athletes' performance


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Age group Requirements

Age Dosage

Infant (0-6) month 1.7 mg

Infant (7-12) month 1.8 mg

Children(1-3) yrs 2mg

Children (4-8) yrs 3mg

Children (9-13)yrs 4mg

Adult men and women(+14)yrs 5mg

Pregnant women 6mg

Breastfeeding women 7mg

United Kingdom RDA: 6 mg/day


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Deficiency:

Pantothenic acid deficiency is

exceptionally rare and has not been

thoroughly studied.

Patients with digestive problem

In starvation ,malnutrition cases

and

limited volunteer trials.


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Clinical man ifes tat ions :

Fatigue,irratibilty and apathy,dermatitis, alopecia and ulcer

numbness, paresthesia, and

muscle cramps

HYPOGLYCEMIA

Adrenal insufficiency andhepatic encephalopathy
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TreatmentAll symptoms corrected and

reversed with the return of

pantothenic acid,either by :

Food

Or

Synthetic supplementation.


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Supplementation Pantothenol

More stable form of thevitamin and is often foundin multivitamin

supplements Calcium pantothenate

more stable thanpantothenic acid in the

digestive mentation mayimprove oxygen utilizationefficiency and reducelactic acid accumulation inathletes.


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Antagonists:

Methylpantothenic acid.

Desthio-coenzymeA.

Hopantenate.


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Toxicity

no Tolerable Upper Level Intake(UL) has been established for

the vitamin.Toxicity of pantothenic acid is

unlikely

massive doses (e.g., 10 g/day)may only yield mild intestinal

distress


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