Chemistry of lipids prostaglandins ppt BIOCHEMISTRY vkunder637@gmai.com

CHEMISTRY OF LIPIDSPROSTAGLANDINS

Dr Vijay Marakala Dr. Vijay Marakala, MBBS, MD.

Assistant professor BIOCHEMISTRY SIMS & RC

EICOSANOIDS

Eicosanoids are formed from 20 carbon PUFA arachidonic acid

Eicosanoids

Prostanoids

Prostaglandins

PG

Prostacyclins

PGI

Thromboxanes

TX

Leukotriens

LT

What is Eicosanoids? Classification

PROSTAGLANDINS

PROSTAGLANDINSWhy PG?

Structure

Location

Prostaglandins ClassificationA,B,C…I

PG Subclassification1,2,3

PGF1 &PGF

2α β

PROSTAGLANDINS[PG]

Nomenclature

Classification

Subscript

Nomenclature

Classification

Subscript

Nomenclature

Classification

Subscript

PROSTAGLANDINS

Hormones?

Primary PG

Other PG

PG

Act like local

hormones16 naturally occurring

PG

7 are found throughout the body

PROSTAGLANDINS - FUNCTIONS

Effects on GIT

Effects on Inflammati

on

Effects on Respiratory

tract

Effects on uterus

Effects on CVS

PROSTAGLANDINS - FUNCTIONS

PGI2

VasodilatationInhibits platelet aggregation

PGA and PGE class prostaglandins lower blood pressure.

Effects on CVS

PROSTAGLANDINS - FUNCTIONS

PGF2

Inducing labor

Effects on

uterus

PROSTAGLANDINS - FUNCTIONS

PGF-BronchoconstrictionPGE-Bronchodilator

Effects on

Respiratory tract

PROSTAGLANDINS - FUNCTIONS

PGE2

Involved in inflammatory response

Effects on Inflammati

on

PROSTAGLANDINS - FUNCTIONS

PGE2

suppress gastric acid secretion

Effects on GIT

First isolated from blood platelets, thrombocytes

TXA2

Subscript number denotes number of double bonds

Capital letters – designate class

Most commo

n

Thromboxanes [TX]

Increase platelet aggregation

Vasoconstriction

Mobilize intracellular calcium

Smooth muscle contraction

Bronchoconstriction

Thromboxanes - FUNCTIONS

LEUKOTRINES WERE SO NAMED BECAUSE THEY WERE INITIALLY DESCRIBED IN LEUCOCYTES

Grouped into 5 classes [A to E]

Subscript number denotes number of double bonds

LTC4

Leukotrines [LT]

Increase chemotaxis

Facilitate inflammation & allergic reactions

Contraction of smooth muscle

Bronchoconstriction

Vasoconstriction

Leukotrines - Functions

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Time fora short break

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HYDROLYSIS SAPONIFICATION RANCIDITY

OXIDATION HYDROGENATION

CHEMICAL PROPERTITES OF FAT

HYDROLYSIS

The fats are hydrolyzed by the enzymes lipases to yield fatty acids and glycerol

SAPONIFICATIONThe hydrolysis of fats by alkali is called saponification. This reaction resultsin the formation of glycerol and salts of fatty acids which are called soaps

HYDROLYTIC RANCIDITY When butter or other fats are stored, they

often become rancid and hence unpalatable. Rancidity is caused by the growth of

microorganisms which secrete enzymes like lipases.

These split the fats into glycerol and free fatty acids.

The fatty acids impart unpleasant odour and flavour to the fat.

OXIDATIVE RANCIDITY Oils containing highly unsaturated fatty acids

are spontaneously oxidized by atmospheric oxygen at ordinary temperatures.

The oxidation takes place slowly and results in the formation of short chain fatty acids (C4to C10) and aldehydes which give a rancid taste and odour to the fats.

Oxidative rancidity is observed more frequently in animal fats than in vegetable fats.

HYDROGENATION

It converts unsaturated fatty acids of triglycerides into saturated fatty acids.

Commercially hydrogenation is used to convert liquid fats of plant origin to solid cooking fats.

Vanaspati (dalda) is obtained from vegetable oils through this process.

FATS – FACTS AND FANTASIES Irrespective of the source, fat is the most concentrated

form of dietary energy. There is no such thing as low-calorie fat. For weight reduction, the only rule is to eat less and

exercise more. Nutritionally, polyunsaturated fatty acids (PUFAs) are

considered superior. Fats of animal origin are saturated whereas vegetable

oils are unsaturated. Fish oils too are unsaturated and have long-chain-

length fatty acids.

TOMORROW 9AM -10AM TEST ON LIPID CHEMISTRY