1. Saponification number
• gives some clue about the average size of fatty
acids in a given sample of fat
• defined as the number of milligrams of KOH
needed to neutralize the fatty acids in 1 g of fat
• butter (large proportion of short chain FAs) sap. no. 220 –
230
• oleomargarine (long chain FAs) sap. No is 195 or less
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2. Acetyl number
• some fatty acids have hydroxyl groups
OH OH
H3C (CH2)21 CH COOH H3C (CH2)5 CH CH2 CH CH (CH2)7 COOH
cerebronic acid ricinoleic acid
The acetyl number gives the proportion of these hydroxyl-containing
fatty acids in a given sample of fat or oil
acetic anhydride
fatty acid fatty acid fatty acid
OH O C CH3 OH
O +
acetylated fatty acid H3C COOH
titrate with standardized
KOH
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3. Acetyl number
• the acetyl number is the number of
milligrams of KOH needed to neutralize the
acetic acid produced from 1 g of acetylated
fat
– examples:
• castor oil (146 –150)
• cod liver oil (1.1)
• cottonseed oil (21 – 25)
• olive oil (10.5)
• peanut oil (3.5)
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4. Iodine number
I I
H H I2
H H
• measures the degree of un-saturation in a given amount
of fat or oil
• the iodine number is the number of grams of iodine
absorbed by 100 g of fat
• Cottonseed oil: 103 –111
• Olive oil: 79 – 88
• Linseed oil: 175 –202
• frequently used to determine adulteration of
commercial lots of oils
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5. Reichert–Meissl number
• measures the amount of volatile fatty acids
(low MW and water soluble Fats)
• the R-M number is the number of milliliters
of 0.1N alkali required to neutralize the
soluble fatty acids distilled from 5 g of fat
• butter fat has a high R-M number
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6. Phospholipids
• the major components of cell membranes
– phosphoglycerides
O
O O R
fatty acids (hydrophobic tail)
glycerol O R'
O-
O O X
P
O
phosphate
Phospholipids are generally composed of FAs, a nitrogenous base,
phosphoric acid and either glycerol, inositol or sphingosine
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7. O
O O R
fatty acids (hydrophobic tail)
glycerol O R'
O-
O O X
P
O
phosphate
X = H (phosphatidic acid) - precursor to other phospholipids
X = CH2-CH2-N+(CH3)3 phosphatidyl choline
X = CH2-CH(COO-)NH3+ phosphatidyl serine
X = CH2-CH2-NH3+ phosphatidyl ethanolamine
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8. Phosphatidyl inositol
Commonly utilized in cellular signaling
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9. Sphingolipids
Contain sphingosine instead of glycerol
OH
OH
sphingosine NH2
R long chain hydrocarbon
HO
NH2 attach fatty acid here
OH attach polar head group here
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10. 1- phingomyelin (a ceramide)
It is a omnipresent component of animal cell membranes, where it is the
most abundant sphingolipid. It can comprise as much as 50% of the lipids in
certain tissues.It is usually lower in concentration than phosphatidylcholine
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11. 2-Ether glycerophospholipids
• Possess an ether linkage instead of an acyl
group at the C-1 position of glycerol
– platelet activating factor (PAF)
– A potent mediator in inflammation, allergic response
and shock, also responsible for asthma-like symptom
– The ether linkage is stable in either acid or base
– Plasmalogens: cis α, β-unsaturated ethers
• The alpha/beta unsaturated ether can be
hydrolyzed more easily
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12. 3- Ether glycerophospholipids
O CH3
O CH3
-O P O CH2 CH2 N CH3
-O P O CH2 CH2 N CH3
O CH3 O CH3
H2C CH CH2 H2C CH CH2
O O O O
H
C O
C O
CH3 H
A choline plasmalogen
platelet activating factor or PAF
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13. 4-Glycolipids
HO R
O
NH R'
O SUGAR polar head is a sugar
beta linkage
There are different types of glycolipids: cerebrosides, gangliosides,
lactosylceramides
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14. GLYCOLIPIDS
• Cerebrosides
• One sugar molecule
– Galactocerebroside
– Glucocerebrosides
• Sulfatides or sulfogalactocerebrosides
• A sulfuric acid ester of galactocerebroside
• Globosides: ceramide oligosaccharides
• Lactosylceramide
– 2 sugars ( eg. lactose)
• Gangliosides
• Have a more complex oligosaccharide attached
• Biological functions: cell-cell recognition; receptors for
hormones
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15. 5- Cardiolipids
O O
O H2C O C R1 R4 C O CH2 O
R2 C O C H O H O H C O C R3
H2C O P O CH2 C CH2 O P O CH2
OH OH OH
glycerol
glycerol
glycerol
A polyglycerol phospholipid; makes up 15% of total lipid-phosphorus
content of the myocardium – associated with the cell membrane
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16. 6-Sulfolipids
• also called sulfatides or cerebroside sulfates
• contained in brain lipids
• sulfate esters of cerebrosides
• present in low levels in liver, lung, kidney,
spleen, skeletal muscle and heart
• function is not established
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17. STEROIDS
• Naturally occurring compounds having
perhydrocyclopentanophenanthrene nucleus in their
structure
• The ring contains 17 carbon atoms
• Generally contain CH3 at carbon 10 and 13
18
12 17
11
19 C 13 D 16
1
2 9 14 15
10
A B 8
3 5 7
4 6
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18. Animal sterol-cholesterol
• It is the most abundant steroid
• Found in animal tissues and not in plants
• 140 g of cholesterol is present in normal
human adult
• Structural formula is C27H45OH
• Considering asymmetric carbon atoms 512
stereoisomers are possible
• The most abundant isomers are C3 (OH) and
C5-10 fusion
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TOMORROW

19. Animal sterol-cholesterol
• Chemical structure
CH3 at 10 and 13 Iso-octanyl at C17
Un-saturation between C5 and C6
OH at C3
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20. CHOLESTEROL FACTS
• It is synthesized from acetyl CoA and eliminated as bile
acids
• It is a precursor of all other steroids in the body
• It is a product of animal metabolism – found in foods of
animal origin
• It is an amphipathic lipid (hydrophobic and hydrophilic
portions)
• stored in the form ester in most of tissues.
O
||
R-C-O
hydrophilic
Cholesterol ester (1st ring only)
R = fatty acid hydrocarbon chain
HO
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21. physical properties
white crystalline solid, tasteless and odorless
oxidized on exposure to air
acts as insulator to nerves and brain tissue
essential structural component of membranes
transported in the circulation in lipoproteins
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22. ROLES OF CHOLESTEROL
AND BILE ACIDS AND ITS SALTS
The physiological roles of cholesterol include:
c) an important lipid component of biological membranes
d) precursor of steroid hormones and
e) source of bile acids
Bile acids are polar derivatives of cholesterol and aid in:
c) lipid digestion
d) lipid absorption
e) cholesterol excretion
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23. Cholestanone (ketones)
Oxidation
Carboxylic acids Drastic oxidation
Cholesterol esters Cholesterol Mixture of
ketones and
halogens
hydrogen
hydroxy acids
Cholesterol dihalides Dihydrocholesterol
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