Download MBBS Biochemistry PPT 7 L8 Eicosanoids Lecture Notes

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Name Of Eicosanoids

? Eicosanoids is a Generic term for the 20

Carbon related compounds like:

I. Prostaglandins (PGs)

I . Prostacyclins (PGI2)

I I. Thromboxanes (TX)

IV. Leukotrienes (LT)

V. Lipoxins (LX)

VI. Resolvins

VII. Eoxins
Biosynthesis Of Eicosanoids

? Eicosanoids are derivatives

of Nutritional Essential

Fatty acid/PUFAs.
? Eicosanoids are biosynthesized in the body

from PUFAs:

1.

Mostly from Arachidonic

acid/Eicosatetraenoic acid

(PUFA)/Omega 6 Fatty acid

2.

Minorly from Timnodonic

acid/Eicosapentaenoic /Omega 3 Fatty

acid

? During Eicosanoid Biosynthesis

Mostly

? Arachidonic acid is released by

Phospholipids Viz: Lecithin/PIP3

? By Phospholipase A2 activity



?Eicosanoids has very

short half life

?From seconds to few

minutes

Classification Of Eicosanoids
? Prostanoids : Obtained by

Cycloxygenase System :

?Prostaglandin
?Prostacyclins
?Thromboxanes

? Leukotrienes and Lipoxins are
obtained by Lipoxygenase System

Prostaglandins are Derivative of

Arachidonic acid
1. Prostaglandins (PGs)

? Prostaglandins are type of

Eicosanoids.

? PGs also termed as Prostanoids
? Since they are obtained from

parent compound Prostanoic

acid
Biosynthesis Of Prostaglandins

? Per day 1 mg of

Prostaglandins are

biosynthesized in human

body.
? Prostaglandins are derived

from Arachidonic acid by

Cycloxygenase system.

? Phospholipid Lecithin releases

Arachidonic acid

? Arachidonic acid is used for

Prostanoic acid synthesis.

? Prostanoic acid then

biosynthesizes Prostaglandin in

human body.


Structure and Types Of PGs
? Prostaglandin structure is complex

and possess:

?Cyclopentane ring
?Double bond
?Carboxylic and Hydroxyl groups

?Prostaglandins contains

a

?Cyclopentane ring with

Hydroxyl groups at C11

and C15


? Prostaglandins (PG) are of

fol owing Types:

?PG A

?PG B

?PG C

?PG D

?PG E

?PG F

?PG G

?PG H


Occurrence/Distribution Of PGs
Occurrence Of PGs

? Prostaglandin was first seen in

Prostatic secretion and Semen.

? Later it was found that

Prostaglandins are ubiquitous

? Present all over in human body

tissues.

Functions OF Prostaglandins
? Prostaglandins serve as Cell

Signaling Agents/Local

Hormones with.

?Paracrine in action (act on

sites closely where they are

produced/ neighboring cel s).

?Autocrine in action that the

sites where they are produced.

? PGs exert their function

through G-Protein linked

membrane receptors.


Prostaglandins have

diverse functions on

many tissues


?Action of one PG is

different in different

tissues.

?Sometimes PGs bring out

opposing action in same

tissue.

1.

4.

Regulate Blood

Inhibits Gastic secretion

Pressure

2.

5.

FUNCTIONS OF

Promotes Kidney

Help in Parturition

Prostaglandins

Function

3.

6.

Produces pain,

Bronchodilation

inflammation and Fever
1.Role Of PGs In Blood Vessels

PGs Regulate Blood Pressure

? PG A and PG E are Vasodilators.
? PGs lowers the blood pressure by:

?Increasing blood flow and
?Decreasing vascular resistance in

blood vessels.
? PGs are used Therapeutical y

in treating Hypertension.

Prostaglandin occur at

Platelets

Inhibits Platelet

Aggregation

and

Thrombus formation
2. PGs Has Role in Uterus At The Time

Of Parturition

? PG natural y increases

uterine contraction of

smooth muscles which

induces the delivery of baby.


? PGs can be therapeutical y used as

Abortificients during Medical

Termination of Pregnancies (MTPs).

? PGs also arrests postpartum

hemorrhage.
3. Role Of Prostaglandins In Lungs

? PGs in Lungs serve as

Bronchodilators and

Bronchoconstrictor of Lungs.

?PG E-Bronchodilator
?PG F- Bronchoconstrictor
?PG E is used in

treatment of Bronchial

Asthma.

4. Role Of Prostaglandin In GIT
? Prostaglandin in stomach

increases its motility and inhibits

gastric secretion of HCL.

? PG is used in treatment of gastric

ulcers.

5. Role Of Prostaglandins in Kidneys
? PGs in Kidneys increases GFR

and promotes urine formation

and urine out put.

? Thus helps in removing waste

out of the body.

PGs Regulate Sleep and Wake Process

? Use of PG D2 promotes Sleep
6.Effect Of PGs on Metabolism

? PGs Decreases Lipolysis (breakdown of

TAG).

? PGs increases Glycogenesis.
? PGs promotes Steroidogenesis

(Biosynthesis of Steroid hormones)

? PGs promotes mobilization of ionic

Calcium from bones.
Production of PGs

Promote

Fever , Pain , Nausea

Vomiting and Inflammation



Role Of PGs

In Immunity And Inflammation

? Prostaglandins are produced in more

amounts at the time of :

?Fever
?Pain
?Nausea and Vomiting
?Inflammation

? Provide non specific immunity to body
?PGs are more produced in

inflammatory disorders

like Rheumatoid Arthritis.

? Drugs like NSAIDs Aspirin used in

treating inflammatory disorders.

? Inhibits the Enzyme of

Cycloxygenase system

? Which in turn inhibits the

biosynthesis of Prostaglandins.




2. Prostacyclins (PGI2)


Prostacyclins (PGI2)

? Prostacyclins are type of Eicosanoids/

Prostanoids.

? Principally formed in vascular

endothelium

? They are Platelet Aggregation

Inhibition Factors

? Biosynthesized by enzyme Prostacyclin

Synthetase.
Roles of Prostacyclins

? Prostacyclins are Vasodilators.

? Prostacyclins like Prostaglandins

inhibit platelet aggregation.

? Prostacyclins prevent Thrombus/clot

formation.

3. Thromboxanes (TX)
Thromboxanes (TX)

? Thromboxanes are also termed as

Platelet Aggregating Factor (PAF).

? Thromboxanes are

Prostanoids produced by

Thrombocytes (platelets)

? By Enzyme Thromboxy

Synthase.


Structure Of Thromboxanes

?Thromboxanes possess a

cyclic Ether in their

structures.


Types Of Thromboxanes

? TX A and TX B are types of

Thromboxanes.

? TXA2 is more prominent in

human body.

Functions Of Thromboxanes

? Thromboxanes are vasoconstrictors.
? Thromboxanes enhances platelet

aggregation.

? Thromboxanes favors blood clot

formation during blood coagulation.
? Thromboxanes and Prostacyclins

are antagonistic to each other

balancing their activities.

? Increased Thromboxane activity

results in Thrombosis.

4. Leukotrienes
Leukotrienes

? Leukotrienes are type of

Eicosanoids

? Biosynthesized through

Lipoxygenase system in

Leukocytes.

? Leukotrienes are a family

of Eicosanoid

? They are Inflammatory

mediators produced

in leukocytes.


Structure And Types Of Leukotrienes
Leukotrienes Structure and Types

? Leukotrines are Hydroxy derivatives

possessing conjugated Trienes .

? Types of Leukotrienes:

? LTB4, LTC4, LTD4 and LTE4

Occurrence Of Leukotrienes
? Early discovery of

Leukotrienes was in

Leukocytes.

?Leukotrienes are also

produced and present in.

?Mast cells

?Lung

?Heart

?Spleen
Effect Of Leukotrienes

? Leukotrienes are biologically active

components of Slow Reacting

Substances (SRS-A).

? SRS-A are released during Al ergic

reactions/Anaphylaxis.

?Leukotrienes are 100-

1000 times more

potent than Histamine

during al ergic

reactions.
?LTB4 is a potent

chemotactic agent.

(chemical substance which

mediates movement of

cel s).

? Leukotrienes by action are:

?Bronchoconstrictors
?Vasoconstrictors
? LTC4, LTD4 and LTE4 are Slow -

Releasing Substance of

anaphylaxis ( SRS - A ) ,

? SRS-A causes fluid leakage from

blood vessels to an inflamed area.

Levels Of Leukotrienes Increased In

? Al ergies

? Al ergic rhinitis

? Asthma
( Tightening of airways, difficult to breathe)
?Overproduction of

Leukotrienes causes

Anaphylactic shocks.

?An Antiasthmatic drug

Prednisone inhibits

Leukotriene

biosynthesis.


5.Lipoxins

Lipoxins

? Lipoxins are Eicosanoids produced
in Leukocytes of human body.

Roles Of Lipoxins

Lipoxins are essential in maintaining tissue

homeostasis and resolve inflammation.

? Lipoxins are:

?Vasoactive/Vasodilators

?Anti-inflammatory

?Anti-proliferative

?Pro-resolving

?Immunoregulatory

?Chemotactic substances

Omega 6 and Omega 3 Derived

Eicosanoids

Are Opposite in Action
? Omega 6 Derived Eicosanoids
? Prostaglandins:

?Promotes Inflammation

? Omega 3 Derived Eicosanoids
Resolvins and Eoxins are:

?Anti inflammatory
?Anti allergy
?Anti hypertensive
?Anti cancer
?Anti atherosclerotic

Effects of Eicosanoids


? Local pain and irritation
? Bronchospasm
? Gastrointestinal disturbances:

nausea, vomiting, cramping,

and diarrhea.









Biological Actions of Selected

Eicosanoid Molecules

Generation of arachidonic acid metabolites and their roles in inflammation.

The molecular targets of some anti-inflammatory drugs are indicated by a red X.

COX, cyclooxygenase; HETE, hydroxyeicosatetraenoic acid;

HPETE, hydroperoxyeicosatetraenoic acid.
Amphipathic Lipids

Examples Of

Amphipathic Body Lipids

? Phospholipids
? Glycolipids
? Free Fatty acids
? Free Cholesterol
Features Of Amphipathic Lipids

? Structure has both polar and non polar groups
? Partial y soluble
? Orientation of groups:

?Polar group directed towards

water phase

?Non polar group directed in oil

phase/away from water.

Role Of Amphipathic Lipids


? Amphipathic Lipids have fol owing biological

Significances in forming:

? Biomembranes:

(Phospholipid bilayer, Glycolipids and Cholesterol)

? Emulsions:
? In intestine PL help in Lipids Digestion
? Micelles:
? In intestine help in Lipids Absorption
? Lipoproteins:
? For transport of nonpolar/neutral Lipids
? Liposomes:
? Agents for Drug /Gene carrier

Emulsions


Emulsions

? Emulsions are small droplets of

oils miscible in aqueous phase.

? Emulsions are usually formed by

Nonpolar and Amphipathic Lipids

along with Bile Salts in aqueous

phase.
In Human GIT

? Emulsions are formed as

smal , miscible dietary Lipid

droplets in aqueous phase of

intestinal juice in intestinal

lumen.

?Emulsions are formed

during the process of

Emulsification in GIT.
Requirements For Emulsification

? Emulsifying agents :

?Bile salts (Major)
?Amphipathic Lipids (Minor)

? Mechanical force aids

emulsification.

? Emulsifying agents reduces

surface tension.

? Emulsifying agents form a

surface layer of separating

main bulk of nonpolar Lipids

from aqueous phase.
?Emulsions are stabilized

by detergent action of

emulsifying agents.

Emulsification Process

? Emulsification process takes place in an

aqueous phase of intestinal juice in intestinal

lumen and forms Emulsions.

? During Emulsification Hydrophobic or

nonpolar dietary Lipids (TAG) are mixed with

an emulsifying agents:

?Bile salts
?Lecithin( Amphipathic Lipids)
? Mechanical force(provided by

intestinal peristaltic

movement) facilitates the

process of Emulsification.

Types Of Emulsions

I. Oil In Water
I . Water In Oil


Significance Of Emulsions

? Emulsions formed in the intestinal

lumen help in the digestion of dietary

Lipids.

? The dietary large droplets of Fat/Oil

are transformed to smal ,miscible

droplets as Emulsions.
? Emulsions bring the dietary

Lipids in contact with Lipid

digesting Enzymes present in

aqueous phase of intestinal

juice.

Micelles

? Micelles have a disc like shape .
? Critical concentration of Amphipathic

Lipids in aqueous medium form

Micel es(~200 nm).

? Bile salts help in forming Mixed

Micel es.
?Mixed Micel es are

formed in Intestine after

digestion of Lipids.

?By an aggregation of

various forms of dietary

digested Lipids with Bile

salts.

? Aggregation of various

digestive end products of

dietary Lipids covered with a

peripheral layer of Bile salts

form Mixed Micelles in

intestinal lumen.
? Mixed Micel es contain the

non polar Lipids in the

interior portions and polar

Bile salts on the exterior.

Significance Of Mixed Micel es

? Mixed Micelles helps in

absorption of dietary Lipids

? From intestinal lumen into

intestinal mucosal cel s.


Liposomes

? Amphipathic Lipids when exposed to

high frequency sound waves (Ultra

Sonication) in aqueous medium to

agitate particles and form Liposomes.

? Liposomes can be prepared by disrupting

biological membranes by ultra

sonication(>20 KHz )
Structures Of Liposomes

? Liposomes are composite structures made

of largely phospholipids and smal amounts

of other molecules

? Liposomes has spheres of one/ many Lipid

bilayers.

? Liposomes contain aqueous regions(polar

phase) and intermittently lipid bilayer (non

polar phase).


Types Of Liposomes

? Unilamellar Liposome
? Multilamellar Liposome


Applications Of Liposomes

? Liposomes are vehicles for

administration of drug through blood,

targeted to specific organs.

? Topical transdermal delivery of drugs.

? Transfer of Gene into vascular cells


? Water insoluble drugs are carried

in Hydrophobic region of

Liposome.

? Water soluble drugs are carried in

Hydrophilic region of Liposomes.
Biomedical Importances

Of Body Lipids

Roles of 7 Biomedical y Important Lipids

1. Fatty Acids (FAs)
2. Triacylglycerol (TAG)
3. Phospholipids (PL)
4. Lipoproteins (LP)
5. Glycolipids
6. Cholesterol (Free)Cholesterol-Ester(Esterified)
7. Eicosanoids (PGs,PGI,TX,LT,LX,Resolvin)


Body Lipids Functions

1.

Secondary Source of Energy

2.

Energy Storage Lipids- Long term use

3.

Thermal and Electrical Insulators

4.

Cushioning Effect and Shock absorber

5.

Shape and Contour to body

6.

Structural Lipids- Biomembrane components

7.

Cel antigens, receptors, anchoring sites

8.

Signal Transduction and Nerve Impulse conduction

9.

Lung Surfactant helps in normal respiration

10. Emulsifiers helps in Lipid digestion and absorption

11. Transport Lipids

12. Metabolic regulatory Lipids

1.

4.

Builds Membranes

Sources Of Energy, PUFAs

Signal Transmission

,Fat soluble Vitamins

2.

5.

Restores Abundant

FUNCTIONS OF LIPIDS

LUBRICATE

Energy

Cushioning Effect

3.

6.

Nervous Function

Electrical and Thermal

Lung Surfactant,

Insulators

Emulsifiers


Fatty acids of TAG is a

Source of Energy

Energy-Containing Nutrients (C and H)

H+

ATP Electron

Transport

Chain

CO2

O2

H2O


Good About Body Lipids

? Liberate 9 kcal per

? Regulates cell

gram of TAG.

function

? Major fuel at rest

? Maintains membrane

? Endurance Exercise

structure

? Source of :

? Improve nerve

function

?Essential fatty acids

? Provides flavors and

?Fat-soluble vitamins

textures of foods

? Gives satiety value
Disorders Associated To Lipids

? Obesity
? Atherosclerosis
? Respiratory Distress Syndrome
? Fatty Liver
? Hyperlipoproteinemias
? Hypolipoproteinemias
? Necrosis ,Oxidative damage of biomembranes due

to Lipid peroxidation

? Lipid Storage Disorders

Common

Lipids Associated Disorders

? Obesity
? Metabolic Syndrome

?Atherosclerosis
?Coronary Heart Disease
?Hypertension
?Diabetes Mel itus


Lipid Storage Disorders

Inborn Errors Of Lipid Metabolism

? Congenital Defects where

deficient of Enzymes

? Affects an Abnormal

accumulation of Lipid forms

? In cells and tissues affecting

there functionality.
S.No Lipid Storage Disorder Enzyme Defect and

Abnormal Accumulation of

1

Niemann Picks Disease Sphingomyelinase

Sphingomyelins

2

Gaucher's Disease

Beta Glucocerebrosidase

Glucocerebrosides

3

Krabbe's Disease

Beta Galactosidase

Galactocerebrosides

4

Tay Sach's Disease

Hexoseaminidase-A

Gangliosides

5

Farber's Disease

Ceramidase

Ceramides

S.N

Human body Lipids

Associated Disorders

Biochemical Defects Biochemical Alterations

01

Triacylglycerol

Obesity

Excess deposition of

Hyperlipidaemias

Metabolic syndrome TAG in Adipocytes and Hypertriglyceridemia

fatty Liver

Liver

Atheroma's

02

PUFA's

Phrynoderma

Deficiency of PUFA's

Hypolipoproteinemia

03

Cholesterol

Familial

LDL receptor defects

Atherosclerosis

hypercholesterolemia

Occlusions

Tissue Infarcts

04

Phospholipid

Respiratory distress

Low lung surfactant No reduction of surface

syndrome

tension of Alveoli

05

Lipoprotein

Hyperlipoproteinemias

LPL defects

Atherosclerosis



LDL defect

Occlusions

Tangier's disease

HDL defect

Tissue Infarcts

06

Lipidosis

a. Tay Sach's disease

Hexoseaminidase

Accumulation of

OR

Gangliosides

Lipid storage disorders

b. Niemann pick's

Sphingomyelinase

Accumulation of

disease

sphingomyelin

a. Gaucher's disease

Beta

Accumulation of

Glucocerebrosidase

Glucocerebrosides

a. Krabbe's diease

Beta

Accumulation of

Galactosidase

Galactocerebrosides

a. Farber's diease

Ceramidase

Accumulation of

Ceramides
Questions

? Long Answer Questions

? Define Lipids (Bloor's Definition).

Classify Lipids with suitable

examples.

? Define Fatty acids. Classify them

with different modes and suitable

examples.
? What are Compound lipids?

Describe Phospholipids wrt

Chemistry,Types,Nature,SourcesDi

stribution,Functions and

associated disorders of.

? What are Sterols? Describe the

structure, dietary sources,

properties & functions of

Cholesterol.

? Write Short Notes.

? Biomedical importance of various

forms of body Lipids

? Enlist various disorders associated to

Lipid forms with biochemical defect

and alterations.

? Essential fatty acids (PUFAs) & their

role in the body.

? Triacylglycerol/Neutral Fats- Structure

& Function.
? Rancidity- Causes & Prevention.
? Gycolipids/Cerebrosides/Gangliosides
? Lipoproteins- Chemistry, types &

functions

? Eicosanoids/Prostaglandins

? Therapeutic uses of Prostaglandins
? Distinguish between Fats & Waxes
? Nomenclature & Isomerism of fatty acids
? Omega 3 fatty acids and their importance
? Amphipathic nature of lipids and their roles
? Distinguish between Fats & Oils
? Enumerate biomedical important lipids with

their classes

? Properties of Fatty acids.
? Simple Lipids with their examples
? Enumerate Compound Lipids & one

function of each

? Name Derived lipids & their functions
? Trans Fats and their harmful effects
? Tests to check the purity of fats &

oils/Characteristic number of Fats

Revision Questions
? Define Lipids
? Number and Names of Lipid Classes
? Define Derived Lipids
? Examples of Derived Lipids
? Define Fatty acids
? What is Delta and Omega end of FAs
? What is Beta Carbon of a Fatty acid
? 6 Modes of Classification of Fatty

acids

? Fatty acids with one double bond is:--------------
? Name most predominant Fatty acid of human

body-----

? Most easily metabolized fatty acids are :----------

--,____________- and _____________

? Fatty acid with odd and even number carbon

atoms are:

? PUFAs are Fatty acids with---------------------
? Name PUFAs of Omega 3 and 6 types
? Enumerate Lipidosis with enzyme defects
? Are Nutritionally Essential Fatty acids and

PUFAs same

? Name branched Chain and Odd Number

Fatty acids

? Name Cyclic and Hydroxy Fatty acids
? What are Cis and Trans Fatty acids
? Enlist Omega 3 Fatty acids and 3 Main

Roles

? Criteria for Sub classification of Simple

Lipids

? Define Simple lipids
? Examples/Subtypes of Simple Lipids
? What is a Class of Fat/Oil and its chemical

name

? Define Waxes
? Name human body Wax
? Differences of Fats and Oils
? Differentiate between

Cerebrosides and Gangliosides

? Occurrence and Role of TAG
? Definition of Compound Lipids
? Types of Compound lipids
? Sphingophospholipid Example

? Number and Names Of

Glycerophospholipids

? Hormonal role of Phospholipds
? Chemical composition of Lung

Surfactant

? Which Compound Lipid is classified

under classes of Lipid and Protein?
? Enzyme defect in Niemann Picks Disease

? Red Spot Macula is noted in which all

conditions

? In which disorder Ceramides get accumulated

in joints

? Emulsions and Liposomes results due to which

Lipid forms.

? On what criteria's TAG is selected as reservoir

of energy for long term use

? Enumerate various Lipid Storage disorders with

biochemical defect and abnormal accumulated

Lipid form

? What value of L/S ratio shows lung maturity and

immaturity?

? What are components of Lung Surfactant?
? What are roles of Lung surfactant?
? What form of energy source helps in endurance of

exercises of body?

? Which Lipids are associated to biomembranes?
? What are applications of Amphipathic Lipids?
? What clinical conditions shows

Hypercholesterolemia?

? Enzymes associated for Eicosanoids biosynthesis.
? Therapeutic roles of Prostaglandins
Thank You

Biochemistry Department

This post was last modified on 05 April 2022