Vitamin B1, THIAMINE

1. VITAMIN B1
(THIAMINE)
NAME : SHARAYU SUBHASH NAGARE
ROLL NUMBER : 96

2. OBJECTIVE
S :
• CHEMISTRY
• BIOCHEMICAL FUNCTIONS
• RECOMMENDED DIETARY ALLOWANCE
• DIETARY SOURCES
• DEFICIENCY SYMPTOMS
• BIOCHEMICAL CHANGES IN B1 DEFICIENCY
• DRY BERI-BERI AND WET BERI-BERI
• INFANTILE BERI-BERI
• WERNICKE-KORSAKOFF’S SYNDROME
• THIAMINE ANTAGONISTS
• THIAMINE DEFICIENCY DUE TO
THIAMINASE AND PYRITHIAMINASE

3. Thiamine (anti-beri-beri or antineuritic vitamin)
is water soluble. It has a specific coenzyme,
thiamine pyrophosphate (TPP) which is mostly
associated with carbohydrate metabolism.
CHEMISTRY
Thiamine contains a pyrimidine ring and a
thiazole ring held by a methylene bridge.
Thiamine is the only natural compound with
thiazole ring.
The alcohol (OH) group of thiamine is esterfied
with phosphate (2 moles) to form the coenzyme,
thiamine pyrophosphate (TPP or cocarboxylase).
The pyrophosphate moiety is donated by ATP and
the reaction is catalysed by the enzyme thiamine
pyrophosphate transferase.

4. BIOCHEMICAL FUNCTIONS
1. The coenzyme, TPP or cocarboxylase is intimately
connected with the energy releasing reactions in the
carbohydrate metabolism.
2. The enzyme pyruvate dehydrogenase catalyses the
irreversible conversion of pyruvate to acetyl CoA.
This reaction is dependent on TTP, besides the other
coenzymes.
3. α-Ketoglutarate dehydrogenase is an enzyme of the
citric acid cycle. This enzyme is comparable with
pyruvate dehydrogenase and requires TPP.
4. Transketolase is dependent on TPP. This is an
enzyme of the hexose monophosphate shunt (HMP
shunt).
5. TPP plays an important role in the transmission of
nerve impulse. It is believed that TPP is required
for acetylcholine synthesis and the ion translocation
of neural tissue.

5. RECOMMENDED DIETARY
ALLOWANCE :
ADULTS : 1-1.5 mg/day
CHILDREN : 0.7-1.2 mg/day
PREGNANCY AND LACTATION : 2
mg/day

6. DIETARY SOURCES :
Cereals, pulses, oil
seeds, nuts and
yeast.
Mostly concentrated
in outer layer of
cereals.
Animal foods –
pork, liver, heart,
kidney, milk, etc.
Parboiled and
milled rice.

7. Deficiency symptoms
• Deficiency of vitamin B1 results in a condition
called beri-beri.
• Early symptoms of thiamine deficiency : loss of
appetite, weakness, constipation, nausea, mental
depression, peripheral neuropathy, irritability,
etc.
• In adults, two types of beri-beri, namely, wet beri-
beri and dry beri-beri occur. Infantile beriberi
that differs from adult beri-beri is also seen.
• The symptoms of beri-beri are often mixed in
which case it is referred to as mixed beri-beri.

8. BIOCHEMICAL CHANGES IN B1
DEFICIENCY :
Pyruvate concentration in plasma is
elevated and it is also excreted in
urine.
An alteration occurs in the blood brain
barrier permitting the pyruvate to
enter the brain directly.
Impairment in nerve impulse
transmission.
Transketolase activity in RBC is
decreased.

9. DRY BERI-BERI
(Neurological beri-beri)
WET BERI-BERI
(Cardiovascular beri-beri)
1. Associated with
neurological
manifestations resulting
in peripheral neuritis.
2. Edema is not commonly
seen.
3. The muscles become
progressively weak and
walking becomes difficult.
4. The affected depend on
support to walk and
become bedridden, and
may even die, if not
treated.
1. Characterized by edema
of legs, face, trunk and
serous cavities.
2. Breathlessness and
palpitation occurs.
3. Calf muscles are
slightly swollen.
4. Systolic blood pressure
is elevated while diastolic
is decreased.
5. Fast and bouncing pulse
is observed.
6. The heart becomes
weak and death may occur
due to heart failure.

10. BERI-BERI

11. INFANTILE BERI-BERI :
- seen in infants born to mothers suffering from
thiamine deficiency.
- the breast milk of these mothers contains low
thiamine content.
- characterized by sleeplessness, restlessness,
vomiting, convulsions and bouts of screaming due
to cardiac dilation.
WERNICKE-KORSAKOFF
SYNDROME :
• Also know as cerebral beri-beri, mostly seen in
chronic alcoholics.
• Insufficient intake or impaired intestinal
absorption of thiamine.
• Characterized by loss of memory, apathy and a
rhythmical to and fro motion of the eye balls.

12. THIAMINE ANTAGONISTS
Pyrithiamine
Oxythiamine
THIAMINE DEFICIENCY DUE TO
THIAMINASE AND PYRITHIAMINASE
:
Thiaminase is present in certain seafoods. Their
inclusion in the diet will destroy thiamine by cleavage
action and lead to deficiency.
Pyrithiamine, a structural analogue and an
antimetabolite of thiamine is found in certain plants
like ferns. Horses and cattle often develop thiamine
deficiency due to the overconsumption of plant ferns.

13. SOURCES
HARPER’S BIOCHEMISTRY 25TH EDITION
FUNDAMENTALS OF CLINICAL CHEMISTRY BY TIETZ
TEXT BOOK OF MEDICAL BIOCHEMISTRY – A. R. AROOR
TEXT BOOK OF BIOCHEMISTRY – D. M. VASUDEVAN
TEXT BOOK OF BIOCHEMISTRY – M. N. CHATTERJEE
TEXT BOOK OF BIOCHEMISTRY – DR. U. SATYANARAYANA

14. THANK YOU!
GUIDED BY :
DR. PRASHANT SIR
DR. DILEEP SIR
THE MOST AWAITED SLIDE 😁