Lipids are organic compounds that include fats, oils, waxes, and steroids. They are insoluble in water but soluble in nonpolar solvents. The main types of lipids are fatty acids, triglycerides, phospholipids, sterols, and prostaglandins. Fatty acids are the building blocks of lipids and contain long hydrocarbon chains that can be saturated or unsaturated. Triglycerides are composed of fatty acids bound to a glycerol molecule and are the main constituents of fats and oils. Phospholipids and sterols such as cholesterol are important components of cell membranes.

1. LIPIDS
Dr.B.RENGESH | M.Tech., Ph.D.
Associate Professor, Department of Pharmaceutical Technology,
Mahendra Engineering College (Autonomous),
Namakkal District, Tamil Nadu, India

2. v Lipids are organic compounds formed mainly from alcohol and fatty acids
combined together by ester linkage.
v Lipids are biological molecules that are insoluble in water but soluble in
nonpolar solvents (ether, chloroform, benzene, acetone).
v Lipids are the waxy, greasy, or oily compounds found in plants and animals.

3. v They are more palatable and storable to unlimited amount compared to
carbohydrates.
v They have a high-energy value (25% of body needs) and they provide
more energy per gram than carbohydrates and proteins but carbohydrates
are the preferable source of energy.
v Supply the essential fatty acids that cannot be synthesized by the body.
v Supply the body with fat-soluble vitamins (A, D, E and K).
v They are important constituents of cell membrane and nervous system.
BIOLOGICAL IMPROTANCE OF LIPIDS

4. v Stored lipids “depot fat” is stored in all animal cells act as
• A store of energy.
• A pad for the internal organs to protect them from outside shocks.
• A subcutaneous thermal insulator against loss of body heat.
v Lipids provide bases for dealing with diseases such as obesity,
atherosclerosis, lipid-storage diseases, essential fatty acid deficiency,
respiratory distress syndrome,
BIOLOGICAL IMPROTANCE OF LIPIDS

5. CLASSIFICATION OF LIPIDS
contain esters
contain 2 types of components (a
fatty acid & an alcohol)
contain > 2 types of components
(a fatty acid, an alcohol & others)

6. v a fatty acid is a carboxylic acid with a long aliphatic chain, which is either
saturated or unsaturated.
FATTY ACIDS

7. Properties:
• The long, nonpolar hydrocarbon tails of fatty acids are responsible for most
of the fatty or oily characteristics of lipids.
• The carboxyl (COOH) group is hydrophilic (polar) under basic conditions,
such as physiological pH (7.4)
• Fatty Acid Micelles
FATTY ACIDS
Micelles are important in the transport of insoluble lipids
in the blood

8. Characteristics:
• The chain length ranges from 4 to 30 carbons; 12-24 is most common.
• The chain is typically linear, and usually contains an even number of
carbons
• The many fatty acids which occur naturally arise primarily through
variation of chain length and degree of saturation
• There may be one double bond or many, up to six in important fatty acids.
FATTY ACIDS

9. Characteristics:
• When double bonds occur they are almost always cis. If there is more than 1
double bond, they occur at three-carbon intervals
FATTY ACIDS
e.g., -C=C-C-C=C-.
This is called
divinylmethane pattern.

10. • If without double bonds: Saturated Fatty Acids
• If with double bonds: Unsaturated Fatty Acids
o 1 double bond: Monounsaturated fatty acids
o 2 or more double bonds: Polyunsaturated fatty acids
FATTY ACIDS - Classification based on number of double bonds & Nomenclature

11. List of some Saturated Fatty Acids
Common Name Systematic Name
Structural
Formula
Lipid Numbers
Propionic acid Propanoic acid CH3CH2COOH C3:0
Butyric acid Butanoic acid CH3(CH2)2COOH C4:0
Valeric acid Pentanoic acid CH3(CH2)3COOH C5:0
Caproic acid Hexanoic acid CH3(CH2)4COOH C6:0
Caprylic acid Octanoic acid CH3(CH2)6COOH C8:0
Capric acid Decanoic acid CH3(CH2)8COOH C10:0
Myristic acid Tetradecanoic acid CH3(CH2)12COOH C14:0
Palmitic acid Hexadecanoic acid CH3(CH2)14COOH C16:0
Stearic acid Octadecanoic acid CH3(CH2)16COOH C18:0

12. List of some Mono-Unsaturated Fatty Acids
Common Name Chemical Name Lipid Numbers
Myristoleic acid cis-Tetradec-9-enoic acid 14:1 (n-5)
Palmitoleic acid cis-Hexadec-9-enoic acid 16:1 (n-7)
Oleic acid cis-Octadec-9-enoic acid 18:1 (n-9)
Elaidic acid (trans-oleic acid) trans-Octadec-9-enoic acid 18:1 (n-9)
11-Eicosenoic acid (gondoic acid) cis-Eicos-11-enoic acid 20:1 (n-9)

13. Common Name Lipid Numbers Chemical Name
List of some Omega-3 Poly-Unsaturated Fatty Acids
Alpha-linolenic acid 18:3 (n-3) all-cis-9,12,15-octadecatrienoic acid
Eicosapentaenoic acid 20:5 (n-3) all-cis-5,8,11,14,17-eicosapentaenoic acid
Docosahexaenoic acid 22:6 (n-3) all-cis-4,7,10,13,16,19-docosahexaenoic acid
List of some Omega-6 Poly-Unsaturated Fatty Acids
Linoleic acid 18:2 (n-6) all-cis-9,12-octadecadienoic acid
Gamma-linolenic acid 18:3 (n-6) all-cis-6,9,12-octadecatrienoic acid
α-linolenic acid 𝛄-linolenic acid

14. • Shorter fatty acids usually have lower melting points than longer ones
(stearic acid [18C] = 70ºC, palmitic acid [16C] = 63ºC)
FATTY ACIDS – Melting Property
• The cis-double bonds in
unsaturated fatty acids put an
inflexible “kink” in the carbon
chain, preventing the molecules
from packing together as tightly
as saturated fatty acids do.

15. • Animal fats and
vegetable oils are
esters composed of
three molecules of a
fatty acid connected to
a glycerol molecule,
producing a structure
called a triglyceride or
a triacylglycerol
STRUCTURE OF FATS AND OILS
TRIGLYCERIDES

16. • The fatty acids in a triglyceride molecule are usually not all the same;
natural triglycerides are often mixtures of many different triglyceride
molecules
TRIGLYCERIDES

17. • Fats are triglycerides that are solids at room temp.
– usually derived from animals & mostly saturated fatty acids
• Oils are triglycerides that are liquids at room temp.
– usually derived from plants or fish & mostly unsaturated fatty acids
TRIGLYCERIDES

18. TRIGLYCERIDES - Hydrolysis

19. TRIGLYCERIDES - Saponification
carboxylate salts
of the fatty
acids

20. TRIGLYCERIDES - Hydrogenation

21. • Waxes are simple lipids contain a fatty acid joined to a long-chain (12-32
carbons) alcohol
WAXES

22. • Waxes are insoluble in water, and not as easily hydrolysed as fats and oils.
They often occur in nature as protective coatings on feathers, fur, skin,
leaves, and fruits.
• Sebum, secreted by the sebaceous glands of the skin, contains waxes that
help to keep skin soft and prevent dehydration.
• Waxes are used commercially to make cosmetics, candles, ointments, and
protective polishes.
WAXES

23. • Phosphoglycerides are complex lipids that are major components of cell
membranes. Phosphoglycerides and related compounds are also called
phospholipids.
PHOSPHOGLYCERIDES

24. • The most abundant phosphoglycerides contain the alcohols choline,
ethanolamine, or serine attached to the phosphate group.
PHOSPHOGLYCERIDES - Aminoalcohols

25. • Phosphoglycerides that contains the aminoalcohol ‘choline’ are called
lecithins.
• The fatty acids at the first and second positions are variable, so there are a
number of different possible lecithins.
• They act as an emulsifying agent
PHOSPHOGLYCERIDES – (Aminoalcohol) – Lecithin

26. • Phosphoglycerides that contains the aminoalcohol ‘ethanolamine or serine’
are called lecithins.
• Cephalins are found in most cell membranes, and are particularly abundant in
brain tissue. They are also found in blood platelets, and play a role in blood-
clotting.
PHOSPHOGLYCERIDES – (Aminoalcohol) – Cephalin

27. • Sphingolipids are complex lipids that contain sphingosine instead of glycerol.
SPHINGOLIPIDS

28. • One important type of sphingolipds are the sphingomyelins.
SPHINGOLIPIDS - Spingomyelin
SPINGOMYELIN
• Sphingomyelins are found brain and nerve tissue,
and in the myelin sheath that protects nerves

29. • Sphingomyelins - a
bilayer that wraps
around nerve cell
axons
SPHINGOLIPIDS - Spingomyelin

30. • Glycolipids are sphingolipids that contain carbohydrates (usually
monosaccharides). They are also referred to as cerebrosides because of their
abundance in brain tissue
SPHINGOLIPIDS - Glycolipids
Cerebroside

31. • Most cell
membranes
contain about
60% lipids
(Amphipathic
Lipids) and
40% proteins.
• The fluid-
mosaic model :
Cell membrane
- Lipid bilayer
BIOLOGICAL MEMBRANES - Membrane Structure
membrane re-
forming @ damage

32. The Fluid Mosaic Model

33. STERIODS
• Steroids are classified as lipids because they are soluble in nonpolar solvents,
but they are non-saponifiable because the components are not held together
by ester linkages
• The basic steroid structure contains four fused rings
• There are three important types of
steroids:
1) Cholesterol
2) Steroid hormones
3) Bile salts

34. STERIODS - Cholesterol
• Cholesterol is the most abundant steroid in the body.
• it is manufactured in the liver.
• It is an essential component of cell membranes, and is a precursor for other
steroids, such as the bile salts, sex hormones, vitamin D, and the
adrenocorticoid hormones.
• There is apparently a correlation
between high levels of cholesterol in
the blood and atherosclerosis.

35. STERIODS – Steroid hormones
• Hormones, molecules that regulate the function of organs and tissues, come
in a variety of forms.
• Some, such as sex hormones and adrenocorticoid hormones, are steroids
• Sex hormones produced in the testes and ovaries regulate the production of
sperm and eggs and aid in the development of secondary sex characteristics
Eg.: testosterone, estradiol, progesterone
• Adrenocorticoid hormones are produced in the adrenal glands (located on
the top of the kidney). Eg.: Glucocorticoids - Cortisol and its derivatives,
cortisone and prednisolone

36. STERIODS
Sex hormones

37. STERIODS
Adrenocorticoid
hormones

38. STERIODS - Bile Salts
• Bile is a yellowish brown or green fluid produced in the liver and stored in
the gall bladder.

39. PROSTAGLANDINS
• Prostaglandins are cyclic compounds synthesized from arachidonic acid.
Like hormones, they are involved in a host of body processes, including
reproduction, blood clotting, inflammation, and fever.
• Prostaglandins have a wide range of biological effects:
– causing pain
– causing inflammation
– causing fever
– affecting blood pressure
– inducing labor (PGE2)

40. PROSTAGLANDINS
Carboprost
Dinoprostone