This document provides an introduction to lipids prepared by Suhaib Kirmani. It discusses that lipids are a diverse group of organic compounds that are hydrophobic and insoluble in water. Lipids serve important functions in the body including energy storage, as structural components of cell membranes, and as regulators of metabolism. Fatty acids are the most common lipid component in the body and can be classified based on their degree of saturation and length of carbon chain. Key properties of fatty acids include their physical properties, which depend on saturation, and their chemical properties like hydrolysis and hydrogenation.

1. DEPARMENT OF PHARMACEUTICAL SCIENCES
LIPIDS
Prepared By: Suhaib Kirmani
B pharm 3rd year

2. INTRODUCTION
 The word lipid is derived from a Greek word "lipos" which means Fat.
 Biological lipids are a chemically diverse group of organic compounds which are insoluble in water. they
are soluble in non-polar solvents such as- ether, chloroform, or benzene.
 Lipids are hydrophobic in nature due to the predominance of hydrocarbon chains. (-CH2 CH2-CH2-) in
their structures.
 In the human body, these molecules can be synthesized in the liver and are found in oil, butter, whole
milk, cheese, fried foods and also in some red meats.
PREPARED BY :Suhaib kirmani

3. INTRODUCTION
 Unlike the proteins, nucleic acids, and polysaccharides, lipids are not polymer.
 They are the chief storage form of energy Fat and oils are the principle stored forms of energy in
many organism.

4. FUNCTIONS
 Storage form of energy (triglycerides)
 Structural components of bio membranes (phospholipids and cholesterol)
 Metabolic regulators (steroid hormones and prostaglandins)
 Act as surfactants, detergents and emulsifying agents (amphipathic lipids)
 Act as electric insulators in neurons
 Provide insulation against changes in external temperature (subcutaneous fat)
 Give shape and contour to the body
 Protect internal organs by providing a cushioning effect (pads of fat)
 Help in absorption of fat soluble vitamins (A, D, E and K)
 Improve taste and palatability of food.

5. CLASSIFICATION OF LIPIDS

6. LIPID METABOLISM
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8411952/
https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/05%3A_Microbial_Metabolism/5.
07%3A_Alternatives_to_Glycolysis/5.7E%3A_Lipid_Metabolism
https://youtu.be/Wm7UR0zCQzM?si=148mKREqc6Amm7xs

7. FATTY ACIDS
 Fatty acids, are included in the group of derived lipids. It is the most common component of lipids in the
body. They are generally found in ester linkage in different classes of lipids. In the human body free
fatty acids are formed only during metabolism.
 Fatty acids are aliphatic carboxylic acids and have the general formula, R—CO—OH, where COOH
(carboxylic group) represents the functional group. Depending on the R group (the hydrocarbon chain),
the physical properties of fatty acids may vary.
 They are amphipathic in nature.
 Fatty acids perform a variety of vital functions in the body, including energy storage. When glucose (a
type of sugar) is unavailable for energy, the body turns to fatty acids to power the cells.

8. CLASSIFICATION OF FATTY ACIDS

9. CLASSIFICATION
They are classified into three types based on their degree
of saturation/unsaturation in the carbon chain:
 If there is no double bond, the fatty acid is saturated.
 If there is one double bond, the fatty acid is
monounsaturated,
 If there are two or more double bonds, the fatty acid is
polyunsaturated.

10. CLASSIFICATION
 They are classified as follows based on their ability or inability to be synthesised by animals, and whose
deficiency can be reversed by dietary addition:
• Essential fatty acids
• Not essential
 They can be functionally classified as follows:
• Short-chain fatty acids: up to 6 carbon atoms
• Medium-chain fatty acids: 8 to 12 carbon atoms.
• Long-chain fatty acids: 14 to 18 carbon atoms
• Very long-chain fatty acids: 20 carbon atoms and up
 Oxygenated fatty acids- They have hydroxyl, keto, and epoxy groups; ricinoleic acid, the main fatty acid in
castor oil, is an example.
 Cyclic fatty acids- They have a cyclic unit with three, five, or even six carbon atoms, similar to prostaglandins

11. NOMENCLATURE OF FATTY ACIDS
 The systematic nomenclature of the fatty acid is based on the hydrocarbon it is derived from.
 The names of the saturated fatty acids end with a suffix -anoic (e.g., octanoic acid), whereas an
unsaturated fatty acid’s name ends with a suffix -enoic (e.g., octadecenoic acid).
 The numbering of carbon atoms begins from its carboxyl carbon, hence the carboxy carbon is given the
number 1. Adjacent carbon atoms are numbered 2, 3, 4 so on. The second, third, and fourth carbons are
also referred to as α, β, and γ.
 The terminal carbon atom on the other end containing the methyl group is referred to as Omega (ω)
carbon. Carbon atoms are alternatively numbered from the ω carbon side as ω1, ω2, ω3, ω4, etc.

12. LIST OF FATTY ACIDS

13. List Of Fatty Acids

14. PROPERTIES
Physical Properties:
Fatty acids are poorly soluble in water in their undissociated (acidic) form, whereas they are relatively
stable as potassium or sodium salts
Thus, the actual water solubility, particularly of longer-chain acids, is often very difficult to determine since
it is markedly influenced by pH
Fatty acids are easily extracted with nonpolar solvents from solutions or suspensions by lowering the pH to
form the uncharged carboxyl group.

15. PROPERTIES
Physical Properties of Saturated Fatty Acids:
 Molecules that fit closely together in a regular pattern
 Strong attractions (dispersion forces) between fatty acid Chains
 High melting points that makes them solids at room temperature.

16. PROPERTIES
Physical Properties of Unsaturated Saturated Fatty Acids:
 Nonlinear chains that do not allow molecules to pack closely
 Weak attractions (dispersion forces) between fatty acid chains
 Low melting points and so are liquids at room temperature

17. PROPERTIES
Chemical Properties Fatty Acids:
Hydrolysis:
Fatty acids are readily hydrolysed by heating with acids or alkyls or superheated steam. When boiled with
sodium or potassium hydroxide solution, the hydrolysis products are sodium or potassium salts of long
chain fatty acids. The latter are called soaps and alkaline hydrolysis is referred to as saponification.

18. PROPERTIES
Some facts about hydrolysis of fatty acids:
 Fatty acids with 4,6 & 8 carbon atoms are released when the fats in milk & butter are hydrolysed.
 Palmitic, stearic & oleic acids are produced during the hydrolysis of
 chocolate & give it an oily/fatty flavour.
 Hydrolysis also happens during deep fat frying.

19. PROPERTIES
Hydrogenation:
 On catalytic hydrogenation at low pressure, hydrogen adds across the C=C of the acid components of
the triglyceride.
 This results in the formation of saturated glycerides which are solids fats at room temperature. This
hydrogenation process is called hardening.

20. PROPERTIES
Rancidification:
 When fats are oils are left exposed to moist air, they develop foul-smell and sour taste. They are said to
have become rancid. The rancidification is caused by two types of reaction:
Oxidation and hydrolysis.
 Oxidative rancidification: It involves the oxidation of in fats and oils to produce volatile carboxylic
acids.
 Hydrolytic rancidification: It involves the hydrolysis of one or more ester linkages in fats and oils to
produce the organic acid.

21. PROPERTIES
Drying:
 When highly unsaturated oils are exposed to air, they undergo oxidation and polymerization to form a thin
waterproof film. Such Oils are called drying oils and the reaction is referred to as drying. Linseed oil, which
is rich in linolenic acid, is common drying oil used in oil based paints. Non drying oils are either saturated
or only moderately unsaturated.

22. THANK YOU