Lipids are a heterogeneous group of hydrophobic organic molecules that serve important functions in the body. They are the chief form of stored energy and include fats, oils, waxes, phospholipids, glycolipids, and other complex lipids. Lipids are classified based on their structure as simple lipids like fats and oils, or complex lipids containing additional components like phospholipids and glycolipids. They undergo chemical reactions like hydrolysis and saponification. Lipids are susceptible to rancidity which deteriorates their quality.

1. BIOCHEMISTRY
[B. Pharm – I Yr.]
Topic: Biomolecules (Lipids)
Umesh Kumar
Assistant Professor
Dept. of Pharm. Chemistry
Hygia Institute of Pharmaceutical Education and Research

2. Contents
• Lipids
• Introduction
• Classification
• Chemical nature

3. LIPIDS
• Lipids (Greek: lipos-fat) are of great importance to the body as the
chief concentrated storage form of energy.
• Lipids are a heterogeneous group of water-insoluble (hydrophobic)
organic molecules.
• Lipids serve additional functions in the body, for example, some fat-
soluble vitamins have regulatory or coenzyme functions, and the
prostaglandins and steroid hormones play major roles in the control of
the body's homeostasis.

4. Definition of Lipids
“Lipids may be regarded as
organic substances relatively
insoluble in water, soluble in
organic solvents (alcohol, ether
etc.), actually or potentially
related to fatty acids and
utilized by the living cells”.

5. Classification of Lipids
1. Simple lipids: Esters of fatty
acids with various alcohols.
a.Fats: Esters of fatty acids
with glycerol. Oils are fats in
the liquid state.
b.Waxes: Esters of fatty acids
with higher molecular weight
monohydric alcohols.

6. 1. Complex lipids: Esters of fatty acids containing groups in addition to
an alcohol and a fatty acid.
a.Phospholipids: Lipids containing, in addition to fatty acids and an
alcohol, a phosphoric acid residue. They frequently have nitrogen
containing bases and other substituents, eg, in
glycerophospholipids the alcohol is glycerol and in
sphingophospholipids the alcohol is sphingosine.
b.Glycolipids (glycosphingolipids): Lipids containing a fatty acid,
sphingosine, and carbohydrate.
c.Other complex lipids: Lipids such as sulfolipids and aminolipids.
Lipoproteins may also be placed in this category.
Classification of Lipids

7. • Precursor and derived lipids: These include fatty acids, glycerol,
steroids, other alcohols, fatty aldehydes, and ketone bodies,
hydrocarbons, lipid-soluble vitamins and hormones.
Classification of Lipids

8. • Hydrolysis: Triacylglycerol undergo enzymatic hydrolysis (by lipase)
to produce free fatty acids and glycerol.
Chemical nature of Lipids

9. • Saponification: The hydrolysis of Triacylglycerol by alkali (NaOH,
KOH) to produce glycerol and soap is known as saponification.
Chemical nature of Lipids

10. • Rancidity:
• Deterioration of fat and oils is known as Rancidity. Resulting in unpleasant
taste.
• Fats containing unsaturated fatty acids are more susceptible to rancidity.
• Unpleasant products like dicarboxylic acids, ketones and aldehydes are
produced.
Chemical nature of Lipids

11. THANK YOU
HYGIA GROUP OF INSTITUTIONS
GHAILA ROAD, GAAZIPUR BALRAM,
FAIZULLAHGANJ, LUCKNOW