For Medical and allied health Science Students objectives: - To describes the structure and functions of major fatty acids found in living organism.

1. Lipids
(Fatty acids)

2. Def:
Lipids are organic substances that are insoluble in water but soluble
in organic solvents (chloroform, alcohol , ether, benzene etc).
LIPIDS
FATTY ACIDS
Alcohol (glycerol / sphingol)

3. FATTY ACIDS
R COOH
Mono carboxylic acids containing a long hydro carbon side
chain with amphipathic in nature
Hydrophilic
Hydrophobic

4. Functions of Fatty acids:
 Occurs mainly as esters of glycerol in neutral fats and oil.
 Serves as a major fuel for most cells
 Precursors of all other classes of lipids
 Amphipathic molecules are important components of biological
membranes
 FA’s derivates serve as hormones (prostglandins) & intracellular
messengers (PI)

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

6. Classification of fatty acids
Fatty acids are mainly 3 types depending on.
- Length of hydrocarbon chain.
- Representation of double bonds of FAs
- Chain nature

7. 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

8. Representation of double bonds of fatty acids
C-
system
Eg: Oleic acid – (C:18:1:∆9) / (C:18:1:ω9)
ω –
system
i.e. C1 being the carboxyl carbon
i.e. C1 being the methyl carbon (ω carbon)

9. 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

10. Depending upon the nature of carbon chain
Straight chain fatty acids
Saturated fatty acid
eg: butanoic acid

11. Depending on the total number of carbon atoms of
Saturated fatty acid
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 ,,

12. 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: Chaulmoogric acid of chaulmoogra seed
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
(doesn't Containing double bonds)
Unsaturated fatty acid
(Containing double bonds)
MUFA
Oleic acid, Palmitoleic
acid
PUFA
Linoleic, Linolenic,
Arachidonic acid

13. ESSENTIAL FATTY ACIDS
(PUFA)

14. Fatty acids, there are required for optimal health & cannot be synthesized
by the body. 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)

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

16. 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

17. Arachidonic acid (omega -6):
Synthesized from linoleic acid by addition of acetyl Co-A) 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 eicosanoids .
•Linolenic acids belongs to omega-6 family

18. Functions of EFAs
Synthesis of Eicosanoids
• Derived from 20C PUFA (arachidonic acid)

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

20. FUNCTIONS OF PGs
• 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

21. Prostacyclins
Vascular endothelium
Thromboxanes
Platelets

22. 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.

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

24. Proper development & functioning of the brain & nervous system.
Required for the membrane structure & functions.
Anti-atherogenic effect
Decreased serum cholesterol level
Prevention of fatty liver.
Increase in fibrinolytic activity
Function of
EFA

25. Skin protector
• EFA (linoleic acid) attached covalently to cerebrosides in the skin
forming acylglucosylceramide.
• Helps to make the skin impermeable to water
• Deficiency of EFA leads to skin lesions & red scaly dermatitis

26. For development of retina & brain
• Docosa hexaenoic acid (cervonic acid) syn from linolenic acid present in
high conc. in retina, cerebral cortex.
• DHA needed for development of the brain & retina during neonatal period
& is supplied via the placenta & milk

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