Their common properties are
1. Water solubility.2. Unstable to normal cooking conditions.3. Excreted in urine.
WATER SOLUBLE VITAMINS
• Thiamine [B1]• Riboflavin [B2]• Niacin [B3]• Pantothenic acid [B5] • Pyridoxine [B6]• Biotin • Folic acid• Cobalamine [B12]
Vitamin B complex
WATER SOLUBLE VITAMINS
Heat labile sulfur containing vitamin
Contains pyrimidine and thiazole ring
Joined by methylene bridge
It is highly alkaline sensitive
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
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
VITAMIN B1 - THIAMINE
FunctionsVITAMIN B1 - THIAMINE
Essential for release of
energy from carbohydrates
Necessary branched chain
amino acid metabolism
Needed for normal
functioning of nervous system
Pyruvate Acetyl - CoA
NAD+ NADH+H+
Lipoate, CoA-SH, FAD
CO2
Oxidative decarboxylation
VITAMIN B1 - THIAMINE
TPP
PDH
α ketoglutarate Succinyl - CoA
NAD+ NADH+H+
Lipoate, CoA-SH, FAD
CO2
Oxidative decarboxylation
VITAMIN B1 - THIAMINE
TPP
VITAMIN B1 - THIAMINE
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
VITAMIN B1 - THIAMINE
Thiamine Deficiency:
Impaired cellular functions
Neurological symptoms,
Edema,Indigestion,Constipation
VITAMIN B1 - THIAMINE
Thiamine Deficiency:
Neurological symptoms,
Edema,Indigestion,Constipation
BERIBERI
VITAMIN B1 - THIAMINE
Thiamine Deficiency:
Types of BERIBERI
Dry beriberi
Wet beriberi
Cerebral beriberi
Infantile beriberi
VITAMIN B1 - THIAMINE
24
A person with “wet” beriberi (edema present) often develops an enlarged heart and related heart failure.
Thiamin deficiencyDry beriberi (no edema)
RIBOFLAVIN - CHEMISTRY
It contains heterocyclic isoalloxazine ring and ribitol a sugar alcohol
It is sensitive to light.
VITAMIN B2 -RIBOFLAVINAbsorption and Transport
Absorbed in small intestine and distributed to all tissues by circulation.
VITAMIN B2 -RIBOFLAVIN
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
• FAD dependent reactions :-1). Succinate dehydrogenase (SDH) :- Succinate Fumarate. FAD FADH2
2). Acyl CoA dehydrogenase:-Acyl CoA α-β Unsaturated Acyl CoA. FAD FADH2
RIBOFLAVIN - DEFICIENCY
Oral
• Angular Stomatitis
• Cheliosis• Glossitis
Facial • Dermatitis of
nasolabial region.
Ocular • Vascularization of cornea
Riboflavin Deficiency
Absorbed in small intestine and reach various tissues through circulation where they are converted to NAD
and NADP.
Niacin [B3]Absorption and transport
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]
• NAD+ dependent reactions Glycolysis :- a) Glyceraldehyde-3-phosphate dehydrogenase. b) Lactate dehydrogenase. TCA cycle :- a) Pyruvate dehydrogenase. b) Isocitrate dehydrogenase. c) α-Ketoglutarate dehydrogenase. d) Malate dehydrogenase.
• NAD+ dependent reactions• Aminoacid catabolism :- a) Branched chain α-Ketoacid dehydrogenase b) Glutamate dehydrogenase• Fat metabolism ;- a) β-Hydroxy acyl CoA dehydrogenase b) β-Hydroxy butyrate dehydrogenase
NADPH dependent• Dihydro folate reductase.• Phenylalanine hydroxylase.• Met Hb reductase.• Cholesterol -7-a hydrolase.• Squalene epoxidase.• HMG- CoA reductase.
• 3-Keto acyl CoA reductase.• Glutathione reductase.• Glucose 6-(P) dehydrogenase.• 6-Phospho gluconate dehydrogenase.
PELLAGRA
54
CAUSES Dietary deficiency
Deficient synthesis
Isoniazid
Hartnup disease
Carcinoid syndrome
NIACIN [B3]Niacin Deficiency
Absorption and transport
Freely absorbed in the intestine and reach various tissues through circulation.
PANTOTHENIC ACID [B5]
Coenzyme-A
TCA cycle
Fatty acid synthesis
Cholesterol synthesis
ACP
Fatty acid synthesis
PANTOTHENIC ACID [B5]-FUNCTIONS
Rare in humansBurning
Foot Syndrome
Experimental animals
AnemiaDermatitisFatty liver
PANTOTHENIC ACID [B5]-Deficiency
Pyridoxine
Pyridoxal
Pyridoxamine
PYRIDOXINE [B6]- CHEMISTRY
• Three compounds derived from pyridine show vitamin B6 activity.
Pyridoxine is easily absorbed and reaches
various tissues through circulation.
In the tissues pyridoxine is converted to pyridoxal and
pyridoxamine.
Absorption and Transport
PYRIDOXINE [B6]
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]-TOXICITY
>500mg/day
Neurologic symptoms:
Sensory neuropathy
Convulsions
It is rare in human adults.
Drug induced pyridoxine deficiency
Isoniazid or isonicotinic acid hydrazine (INH)
Oral contraceptives and excessive alcohol consumption
PYRIDOXINE [B6]
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