Water soluble vitamins Lecture 1 Thiamin & Riboflavin ppt BIOCHEMISTRY

WATER SOLUBLE VITAMINS

Dr Vijay Marakala M.B.B.S.,M.D

Assistant ProfessorBiochemistry

SIMS&RC

Their common properties are

1. Water solubility.2. Except Vitamin B12 others are not stored.3. Unstable to normal cooking conditions.4. Excreted in urine.


• Thiamine [B1]• Riboflavin [B2]• Niacin [B3]• Pantothenic acid [B5] • Pyridoxine [B6]• Biotin • Folic acid• Cobalamine [B12]

Vitamin B complex



Thiamine Riboflavin

Heat labile sulfur containing vitamin

Contains pyrimidine and thiazole ring

Joined by methylene bridge

It is highly alkaline sensitive

Thiamine

Pyrimidine ring Methylene bridge Thiazole ring

VITAMIN B1 - THIAMINE

Sources

Rich Sources

Good sources

Fair sources

• Outer coatings of food grains like rice, wheat and yeast.

• Whole cereals, pulses, oilseeds and nuts.

• Meat, liver and egg and fish.

Vitamin B1 - Thiamine


Thiamine Sources

THIAMINE -RDA

1mg/day

Requirement increases with energy expenditure

Absorption and Transport

It is absorbed in small intestine by active transport mechanism and simple diffusion. Then it reaches liver through circulation.

Ethanol inhibits active transport


THIAMINE-ACTIVE FORM

Thiamin pyrophosphate (TPP or TDP) is the active form of

thiamine.


Thiamin pyrophosphate (TPP or TDP) is the active form of thiamine.

Functions


Essential for release of

energy from carbohydrates

Necessary branched

chain amino acid

metabolism

Needed for normal

functioning of nervous system

In carbohydrate metabolismOxidative decarboxylationTransketolase reactions


Pyruvate Acetyl - CoA

NAD+ NADH+H+

Lipoate, CoA-SH, FAD

CO2

Oxidative decarboxylation


TPP

PDH

α ketoglutarate Succinyl - CoA

NAD+ NADH+H+

Lipoate, CoA-SH, FAD

CO2

Oxidative decarboxylation


TPP


Xylose-5 phosphate Ribose-5 phosphate

Glyceraldehyde-3 phosphate Sedoheptulose-7 phosphate

Transketolase TPP

Thiamine Deficiency:

Failure of carbohydrate metabolism

↓ATP production

Impaired cellular

functions



Impaired cellular functions

Neurological symptoms, Edema,

Indigestion,Constipation



Neurological symptoms, Edema,

Indigestion,Constipation

BERIBERI



Types of BERIBERIDry beriberi

Wet beriberi

Cerebral beriberi

Infantile beriberi



RIBOFLAVIN

RIBOFLAVIN - CHEMISTRY

It contains heterocyclic isoalloxazine ring and ribitol a sugar alcohol

It is sensitive to light.

RIBOFLAVIN - SOURCES

SourcesMilkCheeseEggsMeat Yeast extractsGreen vegetables

27

VITAMIN B2 -RIBOFLAVIN

RDA

1.3 – 1.7mg/day



Absorbed in small intestine and distributed to all tissues by circulation.

RIBOFLAVIN – ACTIVE FORMS

FMNFAD

RIBOFLAVIN – ACTIVE FORMS


Active forms of riboflavin are FMN and FAD.

They act as prosthetic groups of several enzymes.

Catalyzes oxidation-reduction reactions.

Growth, repair, development of body tissues - healthy skin, eyes and tongue

Functions


Co-enzyme activity

FMN - dependent enzymes

FAD - dependent enzymes

RIBOFLAVIN - DEFICIENCY

Oral

• Angular Stomatitis

• Cheliosis• Glossitis

Facial • Dermatitis of

nasolabial region.

Ocular • Vascularization

of cornea

Riboflavin Deficiency


NIACIN

Nicotinic acid Nicotinamide

NIACIN [B3]-CHEMISTRY

NIACIN [B3]- SOURCE

LegumesYeastLiverFish

Meat

Niacin can also be obtained from Tryptophan •

Daily Requirement (RDA):

Niacin [B3]

15-20 mg/day

Absorbed in small intestine and reach various tissues through circulation where they are converted to NAD

and NADP.

Niacin [B3]

Absorption and transport

Niacin [B3]-ACTIVE FORM

NAD+ NADP+

NIACIN [B3]

FUN

CTIO

NS NAD+, NADP+ are involved in oxidation and

reduction reactions

NAD in oxidative pathways- TCA cycle, Glycolysis

NADP in reductive pathways- PPP, Synthesis of cholesterol, FA

NIACIN [B3]

PELLAGRA

Dermatitis

Diarrhoea

Dementia

Death

NIACIN [B3]- DEFICIENCY

CAUSES Dietary deficiency

Deficient synthesis

Isoniazid

Hartnup disease

Carcinoid syndrome

NIACIN [B3]

Niacin Deficiency


Pantothenic acid Pyridoxine

Combination of pantoic acid and β-alanine

PANTOTHENIC ACID [B5]-CHEMISTRY

EggLiverMeatYeastMilk

Cereals

PANTOTHENIC ACID [B5]-SOURCES

Daily requirement (RDA)

PANTOTHENIC ACID [B5]

5-10 mg/day.

Absorption and transport

Freely absorbed in the intestine and reach various tissues through circulation.


ACTIVE FORMS

Coenzyme-A[CoA-SH]

Acyl carrier protein[ACP]



Coenzyme A

Coenzyme-A

TCA cycle

Fatty acid synthesis

Cholesterol synthesis

ACP

Fatty acid synthesis

PANTOTHENIC ACID [B5]-FUNCTIONS

Rare in humans Burning Foot Syndrome

Experimental animals

AnemiaDermatitisFatty liver

PANTOTHENIC ACID [B5]-Deficiency

:

Time fora short break

1009080706050403020100

••••••••••••••••••••••••••••••••••

PYRIDOXINE [B6]

Pyridoxine

Pyridoxal

Pyridoxamine

PYRIDOXINE [B6]- CHEMISTRY

• Three compounds derived from pyridine show vitamin B6 activity.

PYRIDOXINE [B6]

Whole grainsLegumes

LiverYeastMeat

VegetablesFruits

PYRIDOXINE [B6]

Daily requirement (RDA)

2-2.5 mg/day

PYRIDOXINE [B6]

Pyridoxine is easily absorbed and reaches

various tissues through circulation.

In the tissues pyridoxine is converted to pyridoxal and

pyridoxamine.


PYRIDOXINE [B6]

Active form of vitamin B6

Pyridoxal phosphate

PYRIDOXINE [B6]

PYRIDOXINE [B6]

Protein metabolism

Heme synthesis

Glycogenolysis

PYRIDOXINE [B6]

Transamination

Deamination Decarboxylation

Heme synthesis

Production of Niacin

Glycogenolysis

PYRIDOXINE [B6]

Reaction type Example

Transamination Oxaloacetate + glutamate aspartate + ⇔ α-ketoglutarate

Deamination Serine → pyruvate + NH3

Decarboxylation Histidine → histamine + CO2

Condensation Glycine + succinyl CoA → δ-aminolevulinic acid

PYRIDOXINE [B6]-DEFICIENCY

Microcytic hypochromic anaemia Peripheral neuropathy Convulsions

It is rare in human adults.

Drug induced pyridoxine deficiency

Isoniazid or isonicotinic acid hydrazine (INH)

Pencillamine

Oral contraceptives and excessive alcohol consumption

PYRIDOXINE [B6]

Water soluble vitamins Lecture 1 Thiamin & Riboflavin ppt BIOCHEMISTRY

Health & Medicine

Transcript of Water soluble vitamins Lecture 1 Thiamin & Riboflavin ppt BIOCHEMISTRY