Download MBBS Biochemistry PPT 2 L3 Lipid Alcohols Lecture Notes

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Study Of Derived Lipids

Alcohols

Alcohols Involved In

Lipid Structures
3 Alcohols Involved In

Various Forms Of Lipids

1. Glycerol

(C3-Trihydric Alcohol)

2. Sphingol/Sphingosine

(C18-Dihydric Alcohol)

3. Cholesterol

(C27-Monohydric Alcohol)

Alcohols Of Lipids

Are

Classified

As

Derived Lipids


Glycerol is a

Derived Lipid

Obtained from Hydrolysis of

Simple and Compound Lipids
Glycerol/ Glycerin

? Glycerol [C3 ]is a POLYOL
? Glycerol is chemically Trihydric

Alcohol (3 ?OH groups)

? Glycerol has potency to interact

with 3 same or different Fatty

acids .

vGlycerol is a backbone of

Glycerol based Lipids viz:

v Triacylglycerol
v Glycerophospholipids
Glycerol Sources To Human Body

Endogenous and Exogenous Sources




Glycerol



Glucose

Source Of Glycerol To Human

body

? Glucose is responsible for biosynthesis of Glycerol

in human body

? Glucose transforms to Glyceraldehyde,

? Glyceraldehyde on reduction forms Glycerol.
? Glycerol formed is then used for Biosynthesis

of Glycerol based Lipids.

? Glycerol released from hydrolysis of Glycerol

based Lipids is transformed to Glucose.

SPHINGOSINE/SPHINGOL


? Sphingosine is a derived

Lipid.

? Obtained from Hydrolysis of

Sphingolipids
? Sphingosine is a C18, complex Dihydric,

Amino alcohol.

? Sphingosine is biosynthesized in human

body using amino acid Serine.

? Serine provides NH2 group of

Sphingosine.

? Sphingosine forms Sphingolipids

/Compound Lipids with Alcohol

Sphingol

? Examples of Sphingolipids:

?Sphingophospholipids
?Sphingoglycolipids


What Is a Ceramide?

? A Fatty acid linked to an amino

group of Sphingosine

? With an amide linkage form a

Ceramide.


? Ceramide if linked to Phosphate and

Nitrogenous groups forms

Sphingophospholipids.

? Ceramide linked to Carbohydrate

moieties form Sphingoglycolipids.

Sphingosine Based Lipids
Sterols

Common Sterol And Steroids

Vitamin D3

Cholesterol

(cholecalciferol)

(a sterol)







Testosterone

Stigmasterol

(a steroid

(a phytosterol)

hormone)
? Sterols are chemical y

complex, organic monohydric

Alcohols.

? Sterols has cyclic ring

structures

?Sterols have a parent ring
?Cyclo Pentano Perhydro

Phenantherene (CPPP)

nucleus.
Examples Of Sterols

? Cholesterol (Animal Sterol)
? 7 Dehydrocholesterol( Provitamin D)
? Coprosterol (Excretory form Cholesterol)
? Ergosterol (Plant Sterol)
? Sitosterol (Plant Sterol)

Cholesterol

Most abundant Sterol of Human body
Cholesterol

? Cholesterol is an Animal Sterol .

? Cholesterol means Solid Alcohol as it

was first obtained from gal stones of

bile.

? Cholesterol is excreted via bile hence

richly composed in bile ,Gal stones.

Cholesterol

Is A Derived Lipid
? Cholesterol is classified as

Derived Lipid.

? It is derived from hydrolysis of

Cholesterol Ester (Human Body

Wax).

Chemical Structures Of

Cholesterol and Cholesterol Ester


Pentahydrophenantrene

(Sterane)
Structure Of Cholesterol

? Cholesterol is complex, cyclic,

unsaturated, monohydric Alcohol.

? Molecular formula is C27H45OH

? Cholesterol has parent nucleus as

Cyclo Pentano Per hydro

Phenantherene ring system(CPPP).

? The structure of CPPP has four

fused cyclic rings (A,B,C and D)
? Hexane ring A,B,C is a

Phenatrene nucleus.

? D ring is Cyclopentane ring.

? The Structure of Cholesterol Possess:

1. Hydroxyl group (-OH) at C3.

2. Double bond between C5 and C6.

3. 5 Methyl (-CH3) groups.

4. 8 Carbon side chain linked to C17 of

the structure.


Forms Of Cholesterol In Human Body

? Cholesterol exists in two forms:

?Free Cholesterol - 30%

(Amphipathic form)

?Cholesterol Ester - 70%

(Non polar form)


Properties Of Cholesterol

? Cholesterol is white or pale yel owish,

crystal ine ,odorless compound.

? Insoluble in water and soluble in organic

solvents like Ether and Chloroform.

Crystals of Cholesterol Rhombic plates

with Notched edges.
? Qualitative Tests For Cholesterol

detection are:

?Liebermann Burchard Reaction
?Salkowski Reaction
?Zak's Reaction

Sources Of Cholesterol

To Human Body
? Exogenous Sources of Cholesterol:

?Animal Origin Food Items

? Endogenous Source Of Cholesterol:

?Obtained In wel fed condition from

Excess Glucose

Dietary Sources Of Cholesterol

?Cholesterol is exclusively

present in animal foods.


? The dietary rich sources of Cholesterol

animal origin foods like:

?Egg Yolk
?Meat
?Milk
?Butter
?Ghee
?Cream

?Remember Cholesterol

is absent in plant origin

food items.
Endogenous Source Of Cholesterol

? Cholesterol Biosynthesized in

human body from Free Excess

Glucose in Liver.

Transportation Of Cholesterol

?Cholesterol in blood is

transported by Lipoproteins:

? Chylomicrons ( Dietary origin)
? LDL (From Hepatocytes to Extra hepatocytes)
? HDL (From Extra hepatocytes to Hepatocytes)
Occurrence and Distribution Of

Cholesterol in the Body

?70 % of Cholesterol associated

with cel ular components

?30 % of Cholesterol is in the

Blood.
? Cholesterol is richly present in Nervous

tissue Brain.

? Other organs containing Cholesterol are:

?Liver
?Adrenal Cortex
?Gonads
?Intestinal Mucosal cel s
?Skin

Functions Of Cholesterol

Depends Upon

Quality and Quantity


? Cholesterol is constituent of biomembranes

of cel

? It give structure, shape and fluidity to them.

Effects on Membrane without Cholesterol

In Cold Environment In Hot Environment

Rigid/ Not Flexible

Too Flexible

Not Fluid

Very Fluid

May Get damage

Not hold Shape
? Cholesterol richly present in

nervous tissue and covers

Myelin sheaths.

? Cholesterol help in nerve

impulse conduction.

? Cholesterol helps in nerve

impulse transmission since:

?It has high dielectric constant.

?It is a poor conductor of heat

and electricity.
Cholesterol Serves Precursor for

Biosynthesis Of Many Steroids

Derivatives of Cholesterol

? Steroids are derivatives of Sterols.

? Chemical Compounds obtained

from Cholesterol are termed as

Steroidal compounds.


? Derivatives of Cholesterol

? Vitamin D (Cholecalciferol)
? Bile acids (Cholic and Chenodeoxycholic acid)
? Bile Salts are obtained from Bile acids.
? Steroidal Hormones

? ACTH
? Mineralocorticoids
? Glucocorticoids
? Sex Hormones: Androgens, Progesterone,

Estrogen and Testosterone

Bile Acids and Bile Salts


Steroids Hormones

Disorders Related To Cholesterol
?Serum Total

Cholesterol level of a

Healthy human body is

150-200 mg%

Hypercholesterolemia

? Causes for Hypercholesterolemia

? High intake of dietary Cholesterol(animal origin) is a

exogenous source of Cholesterol.

? Elevated endogenous Cholesterol biosynthesis

when a very rich Carbohydrates is ingested.

? Defect in Cholesterol transport by Lipoproteins in

blood retains Cholesterol in blood.


Conditions Of Hypercholesterolemia

?Diabetes mellitus
?Obstructive Jaundice
?Nephrotic Syndrome
?Hypothyroidism

? Hypercholesterolemia leads to :

? Deposits of excess of

Cholesterol in blood vessels.


? Atherosclerosis and atheroma

/plaque formation.

? Increased risk of ischemia and

Myocardial infarction and

Stroke.
?Cholesterol Summary

?Cholesterol is exclusively found only in

animals.

?Exogeneous Cholesterol comes from diet
?Endogeneous Cholesterol is biosynthesized

by the Liver from Glucose product Acetyl-

CoA.

?Cholesterol is an important component of

biomembranes, steroidal hormones, bile

acids and Vitamin D

This post was last modified on 05 April 2022