Its structure, biosynthesis, properties and its role

1. U.MONIKA
I- M.Sc BIO-CHEMISTRY

2. PROSTAGLANDINS
LINOLEIC ACID :
Dietary precursor of Prostaglandins
Linoleic acid is desaturated and elongated to
form Arachidonic acid .
Arachidonic acid is the immediate precursor
of Prostaglandins.
ARACHIDONIC ACID PROSTAGLANDINS
Prostaglandin peroxide synthase

3. EICOSANOIDS – PROSTAGLANDINS (PG)
Arachidonic acid and some other C20 fatty acids
with methylene interrupted bonds gives rise to
EICOSANOIDS which are physically or physiologically and
pharmacologically very active compounds called the
PROSTAGLANDINS.
In fact, they are unsaturated cyclic hydroxy fatty
acid with a 5 - membered ring in 20-C skeleton.
It was first detected in seminal fluid of a man, hence
the name given as Prostaglandins.

4. Besides seminal fluids, these also found in various other
tissues like lung, brain, pancreas etc..
They are lipid soluble, isolated by,
1. COUNTER CURRENT EXTRACTION TECHNIQUE
2. CHROMATOGRAPHY

6. BIO - SYNTHESIS OF PROSTAGLANDINS
CH3 –(CH2)4 [CH=CH–CH2]3 CH=CH(CH2)3 COOH
OXIDATION

7. PROPERTIES OF PROSTAGLANDINS
 Prostaglandins are a group of naturally occuring
substances having in common, a structure which is based on
prostanoic acid, contains 20-C-atoms.
 16 naturally occuring prostaglandins have been
described, but only 7 along with 2 thromboxane are found
throughout the body.
 They are termed as primary prostaglandin.
 They are synthesized at the site of action and made in
all tissue.

8. THREE MAJOR C20 FATTY ACIDS :
The three C20 fatty acids formed are
EICOSATRIENOIC ACID, EICOSATETRAENOIC ACID
(ARACHIDONIC ACID), EICOSAPENTAENOIC ACID.
These fatty acid forms the prostaglandins PG1,
PG2, & PG3 respectively.

10.  Prostaglandins exert very short – lived effects and
catabolized rapidly.
 Inactivation of this PG appears to be mediated by 2
electrons, 15-α- hydroxy prostaglandin dehydrogenase and
Δ13 PG reductase.
 PG are not stored; instead the precursor C20 fatty
acids are present in tissue attached to C-2 Of
phosphoglycerides.
 When needed, the C20 precursor is hydrolysed by
the phospholipase A2, specific for C-2 atom of
phosphoglyceride.

11. TYPES OF PROSTAGLANDINS
The following is a comparison of different
types of prostaglandin, including
1) PROSTAGLANDIN I2 ( Prostacyclin; PGI2),
2) PROSTACYCLIN D2 ( PGD2),
3) PROSTAGLANDIN E2 (PGE2) and
4) PROSTAGLANDIN F2a (PGF2a)

12. BIO-CHEMICAL ROLES
• Help in controlling blood pressure.
• Low levels of prostaglandin causes infertility in man.
• Inhibits lipolysis in adipose tissues which inhibits the
conversion of ATP to cAMP.
• Controls the secretion of gastric HCl
• Extensively used as abortificans, which tends to induce
abortions.

13. • Give relief in asthma and nasal congestion.
• Controls ion transport.
• Stimulate Inflammation.
• Induce sleep

14. CONCLUSION
The structural differences between
prostaglandins accounts for their different biological activities.
They acts as both autocrine and paracrine factors. They are
powerful locally acting vasodilators

16. MCQs
1) Prostaglandins play a major role in many different systems.
Which of it is not a true role ?
a. PGE2 can be used as an abortificants
b. Used to close the patent ductus
c. PGE1 used in the treatment of impotence
d. Inhibiting the conversion of ATP to cAMP
2) Which of the one cannot be converted to PG ?
a. Ceramide
b. Eicosatrienoic acid
c. Eicosapentaenoate
d. Arachidonic acid

17. 3) Which of the following is the precursor of prostaglandin ?
a) Linoleic acid
b) Linolenic acid
c) Eicosapentaenoic acid
d) Arachidonic acid
4) Prostaglandin are what type of fatty acids ?
a) Essential Fatty acids
b) Non – Essential Fatty acids
c) Neither Essential nor Non – Essential
d) Both Essential and Non - Essential