chemistry of lipids prostaglandins ppt biochemistry [email protected]
DESCRIPTION
TRANSCRIPT
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
:
Time fora short break
1009080706050403020100
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