For All Medical & Allied Health Sciences Students

1. Lipids
By
N. Santhosh Kumar
Asst. Professor
Department Of Biochemistry
SIMS & RH
Tumkur

2. Def:
Lipids are organic substances that are insoluble in
water but soluble in organic solvents (chloroform, alcohol,
ether, benzene etc).

3. Energy source
9.5kcal/gm of TG
Structural
role
(Phospholipids &
Cholesterols)
Absorption
of vitamins
Vit- A, D, E & K
BIOLOGICAL
IMPORTANCE
OF LIPIDS
Emulsifying agent
Bile salts
Endocrine function
Steroid, sex hormones & vitamin D
LIPIDS

4. Other functions
Participates on ETC (phospholipids)
Improve taste & palatability of food
Cellular metabolic regulators (Prostaglands &
steroids).
Stored around internal organs (Padding & protects )
It acts as a surfactant
Shape & Smooth appearance of the body

5. Clinical Applications
- Excess fat deposits cause obesity.
- Abnormal in cholesterol & lipoprotein metabolism leads to atherosclerosis &
cardiovascular diseases.
- Cancer

6. FATTY ACID
LIPIDS

7. Def:
--
Fatty acids are mono carboxylic acids containing a long
hydro carbon side chain (also called an acyl chain).
R COOH

8. Sources
Rich sources: Vegetables Oils
Fish
Other sources: Nuts
Seeds
Soya products
Beans and whole grains

9. Classification of fatty acids
Fatty acids are mainly 4 types depending on.
- Total number of carbon atoms.
- Length of hydrocarbon chain.
- Representation of double bonds of FAs
- Chain nature

10. Depending on the total number of carbon atoms
Even chain fatty
acid
Odd chain fatty
acid
common name no of ‘C’ atoms Occurrence
Acetic 2 Vinegar
Butyric 4 Butter
Caproic 6 ,,,
Lauric Acid 12 Coconut oil
Linoleic 18 Vegetable oil
common
name
no of ‘C’
atoms
Occurrence
Propionic 3 Metabolic
intermediate
Valeric 5 ,,

11. Depending on the length of hydrocarbon chain
Acetic (2) Vinegar
Butyric (4) Butter
Caproic (6) Butter
Short chain fatty acids
(2 to 6 carbon atoms)
Medium chain fatty acids
(8 to 14 carbon atoms)
Long chain fatty acids
(16 to 24 carbon atoms)
Caprylic Acid (8) coconut oil
Capric Acid (10) coconut oil
Lauric Acid (12) coconut oil
Myristic Acid(14) palm oil
Palmitoleic Acid (16) animal fats
Oleic Acid (18) olive oil
Linoleic Acid (18) sanflower oil
α-Linolenic Acid (18) linseed oil
Arachidonic Acid (20) liver fats
Behenic acid (22) rapeseed oil
Lignoceric acid (24)

12. Representation of double bonds of fatty acids
C-
system
Eg: Oleic acid – (C:18:1:∆ 9)
ω –
system

13. Cis Configuration Trans Configuration
Cis & trans Configuration of fat
Naturally occurring fatty acids generally have the Cis – configuration
Eg: oleic acid found in olive oil

14. Depending upon the nature of carbon chain
Branched chain Fatty acid
eg: Iso-palmitic acid in wool fat
Phytanic acid in butter
Cyclic fatty acids
Eg: Chaulmoogra oil
Substituted fatty acids (OH / CH3 group)
e.g. cerebronic acid of brain glycolipids.
Ricinoleic acid in castor oil
Straight chain fatty acids
Saturated fatty acid
eg: butanoic acid
Unsaturated fatty acid
MUFA
Oleic acid,
Palmitoleic acid
PUFA
Linoleic, Linolenic,
Arachidonic acid

15. ESSENTIAL FATTY ACIDS
(PUFA)

16. Essential fatty acids are the fatty acids which cannot be
synthesized in the body and they have to be essentially
supplied in the diet.
 Linoleic acid (18:2; ∆ 9,12)
 Linolenic acid (18:3; ∆ 9,12,15)
 Arachidonic acid (20:4; ∆ 5,8,11,14) (semi essential)

17. Linoleic acids (omega-6):
 Eighteen-carbon essential fatty acids that contain two double bonds.
18:2; (∆9,12)
 General formula –CnH2n-3 COOH.
 It is present in Peanut oil, Coconut oil, cotton seed oil, sun flower oil,
soybean oil & egg yolk.
 Linoleic acids belongs to omega-6 family

18. Linolenic acids (omege-3):
•It contain three double bonds (18:3; ∆9,12,15).
•General formula – CnH2 n-5 COOH.
•Present in Lineseed oil, Rapeseed oil, soybean oil, cod liver oil.
•Linolenic acids belongs to omega-3 family

19. Arachidonic acid (omega -6):
It is semi essential (synthesized from linoleic acid by addition of
acetyl CoA).
It contain four double bonds (C20: 4; ∆5, 8, 11, 14).
General formula – CnH2n-7 COOH.
Present in Peanut oil & animal fats.
Arachidonic acid is a precursor for prostaglandins & Leukotrienes.

20. Proper development and functioning of the brain and nervous system.
Involved in transport of cholesterol & formation of lipoprotein
Required for the membrane structure & functions.
Prolongation of clotting time.
Decreased serum cholesterol level
Formation of Prostagland
Prevention of fatty liver.
Increase in fibrinolytic activity
Function of
EFA

21. Deficiency of EFA
•Cessation of growth.
•Skin lesions
•Dermatitis
•Poor wound healing & Loss of hair.
Abnormal metabolism of EFA:
Cystic fibrosis.
Hepato renal syndrome,
Cirrhosis.

22. Eicosanoids
• Derived from 20Carbon PUFA (arachidonic acid)

23. Silent features of all PGs:
- 20C FAs
- cyclopentane ring
- OH gp at 15th position
- Trans double bond at 13th position

24. FUNCTIONS
• PG –A & D: Potent vasodilators , Inhibits gastric secretions
• PG –E1 & E2: Relax the bronchial & tracheal musculatures
• PG –F: Contract the bronchial & tracheal musculatures
• PGF1α & F2α: Increased capillary permeability
• PGF2: Stimulates the uterine muscle

25. Prostacyclins
Vascular endothelium
Thromboxanes
Platelets

26. Leukotrienes (LTs) & lipoxins (LXs)
-Conjugated trienes formed from eicosanoic acid
- Synthesized in leucocytes, mast cells & macrophages by lipoxygenase
pathway
Structure:
LTs & LXs have no ring structure but having conjugated double bonds.

27. Leukotrienes (LTs)
- Increases vascular permeability
- Mediators in inflammation reactions.
- Stimulate Chemotaxis & chemokinines of neutrophils & eosinophils.
Lipoxins (LX)
Vasoactivator
Immunomodulatory and anti-inflammatory actions.

28. Next PPT
CL-02 Lipid classification & Simple lipids